Adoption de l`alimentation méditerranéenne basée sur la théorie de

Transcription

Adoption de l’alimentation méditerranéenne basée
sur la théorie de l’autodétermination : Différences
entre les hommes et les femmes
Thèse
Vicky Leblanc
Doctorat en Nutrition
Philosophiae Doctor (Ph.D.)
Québec, Canada
© Vicky Leblanc, 2015
RÉSUMÉ
L’alimentation méditerranéenne est reconnue comme un modèle de saine alimentation et
ses bienfaits sur la santé cardiovasculaire sont bien documentés. Puisque des différences
entre les hommes et les femmes ont été rapportées quant aux habitudes alimentaires et à la
modification de celles-ci en réponse à des interventions, on peut se questionner à savoir si
les hommes et les femmes peuvent retirer les mêmes bénéfices en adoptant cette
alimentation. D’autre part, la motivation constitue un facteur déterminant dans les
changements alimentaires et des évidences suggèrent que la motivation autodéterminée est
associée à l’adoption et au maintien de comportements alimentaires sains. Peu d’études ont
cependant évalué l’importance de la qualité de la motivation impliquée dans les
changements alimentaires, et aucune ne semble avoir considéré les différences potentielles
entre les hommes et les femmes. L’étude présentée dans cette thèse visait à déterminer
l’influence du genre dans l’adoption d’une alimentation de type méditerranéen en réponse à
un programme d’éducation en nutrition basé sur une approche motivationnelle auprès
d’individus présentant certains facteurs de risque cardiovasculaire. Afin de rencontrer cet
objectif, 64 hommes et 59 femmes préménopausées ont participé à un programme
d’éducation en nutrition de 12 semaines basé sur l’approche de l’entretien motivationnel.
L’intervention nutritionnelle visait à promouvoir la motivation autodéterminée, plus
particulièrement en soutenant la satisfaction des besoins d’autonomie, de compétence et du
sentiment d’attachement des individus dans la détermination d’objectifs alimentaires et de
stratégies favorables à adopter. L’intervention comportait trois rencontres de groupe, trois
rencontres individuelles et quatre suivis téléphoniques avec une nutritionniste. Une
amélioration similaire de l’adhésion à l’alimentation méditerranéenne a été observée chez
les hommes et les femmes en réponse à l’intervention, mais avec des changements plus
prononcés de certaines composantes alimentaires chez les hommes. Une augmentation de la
motivation autodéterminée était associée à une amélioration de l’adhésion à l’alimentation
méditerranéenne chez les hommes seulement. Des changements métaboliques plus
prononcés ont été observés chez les hommes. En conclusion, nos résultats indiquent que le
programme d’éducation en nutrition basé sur une approche motivationnelle a contribué à
l’amélioration des apports alimentaires et à la diminution de facteurs de risque
cardiovasculaire, plus particulièrement chez les hommes.
iii
ABSTRACT
The Mediterranean diet is now recognized as one of the best models of food patterns and its
cardioprotective effects are well established in the literature. As evidence suggests
differences between men and women in eating habits and in dietary changes in response to
interventions, it can be questioned whether men and women could get the same health
benefits from the adoption of the Mediterranean diet. It has also been suggested that
motivation is an important factor in the context of dietary changes and some studies
indicate that self-determined motivation toward eating is associated with the adoption of
healthy dietary behaviors and long-term adherence to those changes. However, few studies
assessed the importance of quality in motivational factors related to dietary changes, and to
our knowledge, none has considered potential differences between men and women. This
study aimed at assessing the impact of gender in the adoption of a Mediterranean diet in
response to a nutritional education program based on a motivational approach, in men and
women presenting risk factors for cardiovascular disease. To meet this objective, 64 men
and 59 premenopausal women were recruited into our 12-week nutritional education
program based on the motivational interviewing approach. The nutritional intervention
aimed at promoting self-determined motivation, more precisely in a context that fosters
satisfaction of basic psychological needs for autonomy, competence, and relatedness in the
determination of dietary changes and potential strategies. The nutritional intervention
included three group sessions, three individual sessions and four follow-up telephone calls
with a registered dietitian. Both men and women increased their adherence to the
Mediterranean diet in response to the nutritional intervention, although men showed more
pronounced changes in some specific food groups. A positive association between
increases in self-determined motivation and increases in the adherence to the Mediterranean
diet was observed in men only. Men also showed more pronounced changes in metabolic
variables. In conclusion, our results indicate that the nutritional intervention program based
on a motivational approach led to improvement in dietary intakes and to decreases in
cardiovascular risk factors, more particularly in men.
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TABLE DES MATIÈRES
RÉSUMÉ .............................................................................................................................. iii
ABSTRACT............................................................................................................................ v
TABLE DES MATIÈRES ................................................................................................... vii
LISTE DES TABLEAUX .....................................................................................................xi
LISTE DES FIGURES ....................................................................................................... xiii
LISTE DES ABRÉVIATIONS ............................................................................................ xv
REMERCIEMENTS .......................................................................................................... xvii
AVANT-PROPOS ...............................................................................................................xxi
INTRODUCTION GÉNÉRALE ............................................................................................ 1
CHAPITRE 1 : Revue de littérature ....................................................................................... 5
1.1 Prévalence des maladies cardiovasculaires au Canada .................................................. 7
1.2 Modèles de saine alimentation proposés dans la littérature ........................................... 9
1.2.1 Évaluation des habitudes alimentaires plutôt que les apports en nutriments ......... 9
1.2.2 Régime DASH ........................................................................................................ 10
1.2.3 Profil de type Prudent ............................................................................................ 10
1.2.4 Guide alimentaire canadien................................................................................... 11
1.2.5 Régime méditerranéen ........................................................................................... 14
1.2.6 Méthodes permettant de calculer un score d’adhésion aux différents modèles de
saine alimentation ............................................................................................................. 16
1.3 Bienfaits de l’alimentation méditerranéenne................................................................ 18
1.3.1 Bienfaits sur la santé.............................................................................................. 18
1.3.2 Bienfaits sur la qualité de vie ................................................................................ 21
1.4 Déterminants des choix alimentaires sains................................................................... 22
1.4.1 Définition des concepts de genre et de sexe .......................................................... 23
1.4.2 Différences relatives au genre quant aux habitudes et comportements alimentaires
............................................................................................................................... 24
1.4.3 Impact de l’alimentation sur la santé : l’influence du sexe ................................... 27
1.5 Différences entre les hommes et les femmes en réponse à une intervention
nutritionnelle visant la prévention de maladies cardiovasculaires ........................................ 29
1.6 Différences entre les hommes et les femmes dans le contexte de l’alimentation
méditerranéenne .................................................................................................................... 30
1.6.1 Différences entre les hommes et les femmes dans l’adhésion à l’alimentation
méditerranéenne ................................................................................................................ 30
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1.6.2 Différences entre les hommes et les femmes dans la réponse à une intervention
nutritionnelle basée sur l’alimentation méditerranéenne ................................................ 31
1.7 Théories de changements de comportements liés à la santé ........................................ 33
1.7.1 Théorie sociale cognitive ...................................................................................... 33
1.7.2 Modèle transthéorique .......................................................................................... 35
1.7.3 Théorie de l’autodétermination ............................................................................. 37
1.8 Approche de l’entretien motivationnel ........................................................................ 45
1.8.1 Définition et principes ........................................................................................... 45
1.8.2 Complémentarité entre la théorie de l’autodétermination et l’entretien
motivationnel .................................................................................................................... 47
1.8.3 L’efficacité de l’entretien motivationnel pour améliorer les comportements liés à
la santé.............................................................................................................................. 49
1.8.4 L’efficacité de l’entretien motivationnel pour améliorer les changements
alimentaires ...................................................................................................................... 51
CHAPITRE 2 : Problématique ............................................................................................. 53
CHAPITRE 3 : Différences relatives au genre dans les apports alimentaires : quelle est la
contribution des variables motivationnelles? ....................................................................... 59
RÉSUMÉ.............................................................................................................................. 63
ABSTRACT ......................................................................................................................... 65
INTRODUCTION ................................................................................................................ 67
METHODOLOGY ............................................................................................................... 68
Participants ...................................................................................................................... 68
Measurements ................................................................................................................... 70
Statistical Analyses ........................................................................................................... 73
RESULTS............................................................................................................................. 73
DISCUSSION ...................................................................................................................... 75
REFERENCES ..................................................................................................................... 80
CHAPITRE 4 : Différences entre les hommes et les femmes dans les apports alimentaires
et le profil métabolique en réponse à une intervention nutritionnelle de 12 semaines visant
l’adoption de l’alimentation méditerranéenne ...................................................................... 89
RÉSUMÉ.............................................................................................................................. 93
ABSTRACT ......................................................................................................................... 95
INTRODUCTION ................................................................................................................ 97
METHODOLOGY ............................................................................................................... 99
Participants ...................................................................................................................... 99
Study Design ................................................................................................................... 100
Measurements of Dependent Variables .......................................................................... 101
Statistical Analyses ......................................................................................................... 103
RESULTS........................................................................................................................... 104
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DISCUSSION ..................................................................................................................... 107
REFERENCES ................................................................................................................... 114
CHAPITRE 5 : Différences relatives au genre dans les effets à long terme d’un programme
d’intervention nutritionnelle visant l’adoption de l’alimentation méditerranéenne :
changements dans les apports et comportements alimentaires, ainsi que dans les variables
anthropométriques et métaboliques .................................................................................... 127
RÉSUMÉ ............................................................................................................................ 131
ABSTRACT........................................................................................................................ 133
INTRODUCTION .............................................................................................................. 135
METHODOLOGY ............................................................................................................. 137
Participants ..................................................................................................................... 137
Study Design.................................................................................................................... 138
Measurements of dependent variables ............................................................................ 139
Statistical analyses .......................................................................................................... 141
RESULTS ........................................................................................................................... 142
DISCUSSION ..................................................................................................................... 144
REFERENCES ................................................................................................................... 150
CHAPITRE 6 : Effets d’un programme d’intervention nutritionnelle basé sur la théorie de
l’autodétermination et visant l’adoption de l’alimentation méditerranéenne: différences
relatives au genre dans la motivation autodéterminée et l’adhésion à l’alimentation
méditerranéenne .................................................................................................................. 171
RÉSUMÉ ............................................................................................................................ 175
ABSTRACT........................................................................................................................ 177
INTRODUCTION .............................................................................................................. 179
METHODOLOGY ............................................................................................................. 181
Participants ..................................................................................................................... 181
Study Design.................................................................................................................... 182
Statistical Analyses.......................................................................................................... 185
RESULTS ........................................................................................................................... 186
DISCUSSION ..................................................................................................................... 189
REFERENCES ................................................................................................................... 194
CHAPITRE 7 : Changements de la qualité de vie liée à la santé suivant une intervention
nutritionnelle visant l’adoption de l’alimentation méditerranéenne : évaluation des
différences de genre chez des hommes et des femmes présentant des facteurs de risque
cardiovasculaire .................................................................................................................. 207
RÉSUMÉ ............................................................................................................................ 211
ABSTRACT........................................................................................................................ 213
INTRODUCTION .............................................................................................................. 215
ix
METHODOLOGY ............................................................................................................. 216
Recruitment of participants and Study design ................................................................ 216
Statistical Analyses ......................................................................................................... 218
RESULTS........................................................................................................................... 219
DISCUSSION .................................................................................................................... 221
REFERENCES ................................................................................................................... 224
CHAPITRE 8 : Conclusion générale ................................................................................. 233
BIBLIOGRAPHIE ............................................................................................................. 247
ANNEXE : Score méditerranéen ....................................................................................... 267
x
LISTE DES TABLEAUX
CHAPITRE 1
Tableau 1. Recommandations nutritionnelles canadiennes visant la prévention des
maladies cardiovasculaires (2013) ................................................................................. 8
Tableau 2. Types d'aliments à privilégier selon le Guide alimentaire canadien ................ 13
CHAPITRE 3
Table 1. Physiological characteristics of men and women ................................................. 85
Table 2. Dietary intakes and eating behaviors in men and women .................................... 86
Table 3. Basic psychological needs, global and eating related motivation in men and
women .......................................................................................................................... 87
Table 4. Association between eating related self-determination index and dietary intakes,
eating behaviors and anthropometric profile in men and women ................................ 88
CHAPITRE 4
Table 1. Baseline characteristics of men and women ....................................................... 120
Table 2. Dietary intakes, Medscore and food group intakes at baseline and after the 12week nutritional intervention program ....................................................................... 121
Table 3. Changes in dietary intakes, Medscore and food group intakes in response to the
12-week nutritional intervention program ................................................................. 123
Table 4. Anthropometric and metabolic variables at baseline and after the 12-week
nutritional intervention program ................................................................................ 125
Table 5. Changes in anthropometric and metabolic variables in response to the 12-week
nutritional intervention program ................................................................................ 126
CHAPITRE 5
Table 1. Characteristics of men and women at baseline ................................................... 156
Table 2. Changes in dietary intakes in men and women .................................................. 157
Table 3. Changes in Medscore and food groups in men and women ............................... 160
Table 4. Changes in anthropometric and metabolic variables in men and women .......... 164
Table 5. Changes in eating behaviors in men and women................................................ 168
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CHAPITRE 6
Table 1. Characteristics of men and women at baseline ................................................... 201
Table 2. Changes in the eating-related self-determination index and its specific forms of
regulation in men and women in response to the 12-week nutritional intervention
program and at follow-up ........................................................................................... 202
Table 3. Associations between changes in eating-related self-determined motivation and
changes in the Medscore and in BMI in men and women .......................................... 205
CHAPITRE 7
Table 1. Characteristics of health-related quality of life in men and women at baseline . 228
Table 2. Changes in health-related quality of life in men and women in response to the 12week nutritional intervention program, and at 6 and 9-month follow-up .................. 229
Table 3. Associations between changes in the Medscore, eating-related self-determined
motivation and body weight and changes in global HRQOL in men and women from
baseline to 6-month follow-up .................................................................................... 232
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LISTE DES FIGURES
CHAPITRE 1
Figure 1. Pyramide de l'alimentation méditerranéenne traditionnelle ................................. 15
Figure 2. Schématisation de la théorie sociale cognitive ..................................................... 34
Figure 3. Schématisation du modèle transthéorique ............................................................ 35
Figure 4. Schématisation de la théorie de l'autodétermination ............................................ 38
Figure 5. Similitudes entre les principes de la théorie de l'autodétermination et de
l'entretien motivationnel ................................................................................................ 49
CHAPITRE 4
Figure 1. Description of the 12-week nutritional intervention program and measurements
performed at baseline and after the end of the intervention ........................................ 119
CHAPITRE 5
performed at baseline, after the end of the intervention and then at 3-month and 6month post intervention ............................................................................................... 155
CHAPITRE 6
Figure 1. Continuum of the Self-Determined Motivation. ................................................ 199
performed at baseline, after the end of the intervention and then at 3-month and 6month post intervention ............................................................................................... 200
CHAPITRE 7
performed at baseline, after the end of the intervention and then at 6 and 9-month
follow-up. .................................................................................................................... 227
xiii
LISTE DES ABRÉVIATIONS
BMI: Body mass index
C : Cholestérol
C-LDL : Concentrations de cholestérol lié aux lipoprotéines de basse densité
C-HDL : Concentrations de cholestérol lié aux lipoprotéines de haute densité
CVD: Cardiovascular diseases
DASH : Dietary Approach to Stop Hypertension
FFQ: Food frequency questionnaire
FSH: Follicle-stimulating hormone
GAC : Guide alimentaire canadien
HRQOL: Health-related quality of life
IMC: Indice de masse corporelle
MCV : Maladies cardiovasculaires
MedDiet: Mediterranean diet
Medscore: Mediterranean score
MI: Motivational interviewing
MTT : Modèle transthéorique
Score Med : Score méditerranéen
SDI: Self-determination index
SDT: Self-Determination Theory
TAD : Théorie de l’autodétermination
TFEQ: Three-Factor Eating Questionnaire
TSC : Théorie sociale cognitive
VAS: Visual analog scale
xv
REMERCIEMENTS
Cette thèse est le résultat d’un projet s’étant échelonné sur un peu plus de quatre ans, qui
aura été un parcours extrêmement riche sur le plan du savoir académique et tout autant pour
l’expérience acquise en recherche. Ma décision de poursuivre au doctorat était
essentiellement basée sur le désir de demeurer dans le domaine de la recherche et de
participer au développement et à la réalisation d’une intervention clinique, et cette belle
opportunité s’est présentée à moi.
Je tiens à remercier plusieurs personnes pour leur soutien tout au long de ce projet de
recherche. Tout d’abord, je tiens sincèrement à remercier ma directrice de recherche,
Simone Lemieux, pour avoir partagé avec moi son expertise comme chercheure, mais
également pour sa grande disponibilité, son écoute, sa confiance et ses précieux conseils. Je
la remercie également pour son soutien dans les moments où je me suis questionnée quant
au chemin que je désirais suivre dans ma carrière professionnelle. Je me sens très choyée
d’avoir eu la chance de la côtoyer pendant toutes ces années!
Je tiens à remercier ma co-directrice, Sophie Desroches, pour son soutien tout au long de
mes études au doctorat. Je remercie également Louise Corneau pour son grand dévouement
tout au long du projet de recherche. Merci à Anne-Marie Hudon, ma partenaire de course
préférée, une amie et une collègue exemplaire avec qui j’ai eu beaucoup de plaisir à
travailler. Merci à Marie-Michelle Royer qui a apporté son aide précieuse dans le
développement du projet et les débuts de l’intervention. Je désire aussi souligner la
contribution de Valérie Guay, Julie Maltais-Giguère, Kim Labonté, Danielle Aubin et
Steeve Larouche dans la réussite du projet, merci à vous!
Je remercie tous mes amis et collègues de l’INAF, qui rendent mon quotidien tellement
agréable!!! Sans vous nommer un à un, sachez que votre présence fait toute la différence
dans notre environnement de travail. Juste un petit mot pour remercier mes « copines » de
bureau, Alex, Marie et Caro… Je suis très heureuse d’avoir pu partager pleins de beaux
xvii
souvenirs avec vous pendant mes études graduées, que ce soit dans le quotidien, à
l’occasion de congrès ou encore lors de nos soupers tartare.
Je tiens à remercier des amies de longue date qui sont bien précieuses à mes yeux malgré la
distance ou nos horaires toujours trop chargés, Sarah, Aboue, Catherine et Marie-Hélène.
Vous amitié apporte énormément à mon bonheur dans la vie! Je veux aussi remercier de
tout cœur ma famille, plus particulièrement mes parents Claire & Daniel et ma sœur
Roxane, pour leur amour et leur appui depuis toujours dans mes choix de vie. Un Merci
particulier à Jean-Robert qui m’a offert son havre de paix pour quelques jours pendant la
rédaction de ma thèse, ce qui m’a fait le plus grand bien! Et finalement, je tiens à remercier
Mathieu pour sa grande écoute et son soutien dans les dernières étapes de ce projet
important pour moi. Merci d’avoir contribué à mon équilibre de vie dans les derniers
mois :) .
On dit que la vie est une aventure que l’on doit oser, le doctorat aura pour moi fait partie de
cette belle aventure!
xviii
Je dédie cette thèse à ma famille.
Merci de m’avoir appris à croire en moi
et à me dépasser dans la vie…
xix
AVANT-PROPOS
Les travaux de recherche présentés dans le cadre de cette thèse ont mené à la rédaction de
cinq articles scientifiques présentés de façon intégrale dans les chapitres 3 à 7. Le premier
article visait à identifier les différences relatives au genre dans les apports et
comportements alimentaires ainsi que dans les variables motivationnelles, puis à déterminer
les associations entre ces variables auprès d'hommes et de femmes préménopausées à
risque de maladies cardiovasculaires. Le second présente les différences de genre dans les
changements alimentaires, anthropométriques et métaboliques en réponse à l'intervention
nutritionnelle de 12 semaines, alors que le troisième présente l'effet de l'intervention à long
terme (3 mois et 6 mois après la fin de l'intervention) sur les apports et comportements
alimentaires, ainsi que sur les variables anthropométriques et métaboliques. Les quatrième
et cinquième articles rapportent les effets de l'intervention sur les changements de
motivation autodéterminée et d'adhésion à l'alimentation méditerranéenne (article 4) et sur
la perception de la qualité de vie (article 5). Ces chapitres sont précédés d’une introduction
générale, d’une revue de la littérature portant principalement sur l’alimentation
méditerranéenne, les différences entre les hommes et les femmes dans le contexte
d’interventions nutritionnelles et la théorie de l’autodétermination, suivi par une
problématique permettant de mettre en contexte la pertinence de notre projet de recherche.
Une conclusion générale suit la présentation des cinq articles scientifiques afin de situer la
contribution de mes travaux de recherche à l’avancement des connaissances dans le
domaine des interventions nutritionnelles cliniques et de faire ressortir les principales
perspectives de recherche.
Les articles présentés dans cette thèse reposent sur la collaboration de plusieurs personnes.
D’abord, ma directrice de recherche, Dr. Simone Lemieux, professeure titulaire à la
Faculté des sciences de l’agriculture et de l’alimentation – École de nutrition de
l’Université Laval, est la principale responsable de la planification et de la rédaction du
projet de recherche en vue d’obtenir du financement, et elle a été impliquée dans toutes les
étapes reliées à la rédaction et l’approbation de chacun des articles présentés dans cette
thèse. Dr. Catherine Bégin, professeure titulaire à la Faculté des sciences sociales – École
xxi
de psychologie de l’Université Laval, a collaboré à la planification et l’élaboration du projet
de recherche en plus de partager avec nous ses expertises dans les domaines du
comportement alimentaire et de la théorie de l’autodétermination. Elle a ainsi apporté une
aide précieuse dans l’interprétation des données des articles présentés aux chapitres 3 à 7.
Anne-Marie Hudon et Marie-Michelle Royer sont toutes deux co-auteurs pour les
articles présentés aux chapitres 4 à 6 puisqu’elles ont été impliquées dans le volet clinique
du projet de recherche dans le cadre de leur maîtrise en nutrition, en plus de participer à la
collecte et à la saisie de données. Louise Corneau, professionnelle de recherche à l’Institut
sur la nutrition et les aliments fonctionnels (INAF), a été en charge de coordonner
l’intervention clinique incluant le recrutement des participants et les visites à l’unité
d’investigation clinique de l’INAF, en plus d’avoir aussi collaboré à la planification et
l’élaboration du projet de recherche. Sylvie Dodin, médecin clinicienne et professeure
titulaire à la Faculté de médecine – Département d’obstétrique et de gynécologie de
l’Université Laval, a été responsable de la supervision des aspects médicaux du projet de
recherche et a également participé à la planification et l’élaboration du projet de recherche.
Louise Corneau et Sylvie Dodin sont co-auteurs pour tous les articles présentés dans cette
thèse (chapitres 3 à 7). En ce qui me concerne, pour l’ensemble des articles présentés aux
chapitres 3 à 7, j’ai agi en tant que premier auteur et j’ai été impliquée dans tous les aspects
reliés à la réalisation du projet de recherche. Plus précisément, j’ai contribué au
développement du programme d’éducation en nutrition de 12 semaines, j’ai réalisé
l’intervention clinique, participé à la saisie de données, pour ensuite procéder aux analyses
statistiques des données du projet. J’ai écrit tous les articles présentés dans cette thèse et
j’ai été en charge du processus de soumission et de révision en vue de publier dans des
revues scientifiques. À l'exception de l’article présenté au septième chapitre, qui a été
soumis à Journal of Nutrition Education and Behavior, l'ensemble des articles scientifiques
présentés dans cette thèse ont tous été publiés ou acceptés pour publication pendant mes
études au doctorat. Voici les références détaillées relatives à chacun des articles
scientifiques qui font partie de cette thèse, ces derniers étant présentés selon la dernière
version soumise aux revues scientifiques.
xxii
CHAPITRE 3
Gender differences in dietary intakes: what is the contribution of motivational variables?
Leblanc V, Bégin C, Corneau L, Dodin S, Lemieux S.
Journal of Human Nutrition and Dietetics. 2015 Feb;28(1):37-46.
CHAPITRE 4
Differences between men and women in dietary intakes and metabolic profile in response
to a 12-week nutritional intervention promoting the Mediterranean diet.
Leblanc V, Hudon AM, Royer MM, Corneau L, Dodin S, Bégin C, Lemieux S.
Nutritional Science. 2015; 4(e13): 1-11.
CHAPITRE 5
Gender differences in the long-term effects of a nutritional intervention program promoting
the Mediterranean diet: changes in dietary intakes, eating behaviors, anthropometric and
metabolic variables.
Leblanc V, Bégin C, Hudon AM, Royer MM, Corneau L, Dodin S, Lemieux S.
Nutrition Journal. 2014 Nov 22;13:107.
CHAPITRE 6
Effects of a nutritional intervention program based on the Self-Determination Theory and
promoting the Mediterranean diet: Gender differences in eating-related motivation and
adherence to the Mediterranean diet.
Leblanc V, Bégin C, Hudon AM, Royer MM, Corneau L, Dodin S, Lemieux S.
Accepté à Health Psychology Open (9 septembre 2015).
CHAPITRE 7
Changes in health-related quality of life following a nutritional intervention promoting the
Mediterranean diet: examination of gender differences in men and women presenting risk
factors for cardiovascular disease.
Leblanc V, Bégin C, Corneau L, Dodin S, Lemieux S.
Soumis à Journal of Nutrition Education and Behavior (24 mai 2015).
xxiii
INTRODUCTION GÉNÉRALE
Malgré une diminution du taux de mortalité liée aux maladies cardiovasculaires (MCV) au
Canada (Agence de la santé publique du Canada, 2015), la prise en charge des facteurs de
risque associés à ces maladies demeure une préoccupation importante au point de vue de la
santé publique. La Société canadienne de cardiologie reconnait l’importance de
l’alimentation en prévention des MCV (Anderson et al., 2013). Dans les dernières années,
le portrait global des recommandations alimentaires pour la santé cardiovasculaire a
quelque peu changé. En effet, les recommandations ont longtemps misé principalement sur
la restriction de l’apport énergétique et en lipides. Bien que ces éléments figurent toujours
parmi celles-ci, davantage d’importance est maintenant accordée à la qualité de
l’alimentation (Anderson et al., 2013). À ce propos, l’alimentation méditerranéenne,
caractérisée par une consommation abondante de fruits et légumes, céréales entières, noix
et légumineuses, d’huile d’olive, par une faible consommation de viandes rouges et de
sucreries, puis par une consommation modérée de vin aux repas (Willett et al., 1995),
constitue une référence en matière de saine alimentation et ses bienfaits sur la santé
cardiovasculaire
ont
été
démontrés
à
maintes
reprises
dans
des
populations
méditerranéennes et non méditerranéennes (Sofi et al., 2014). Par ailleurs, ce mode
alimentaire est composé d’aliments savoureux en plus d’être reconnu comme convivial et
non-restrictif (Willett et al., 1995). Somme toute, ces éléments encouragent l’adoption de
l’alimentation méditerranéenne en prévention des MCV et en font un modèle de saine
alimentation intéressant dans le contexte d’une intervention nutritionnelle.
Bien que de nombreux efforts sont déployés afin de développer des interventions
nutritionnelles efficaces, une lacune importante en pratique clinique s’explique par la
difficulté éprouvée par un professionnel de la santé à soutenir le client dans l’adoption de
changements alimentaires et plus particulièrement dans le maintien de ces changements à
long terme, dans une optique de santé. Un des principaux défis consiste à identifier les
stratégies les plus favorables afin d’intervenir adéquatement auprès de ces individus.
1
D’une part, la motivation est reconnue comme un concept central dans le contexte des
changements alimentaires, bien qu’elle soit généralement considérée en termes d’intensité
plutôt qu’en fonction de la qualité des facteurs de motivation. En ce sens, la théorie de
l’autodétermination s’intéresse à la qualité de la motivation impliquée dans la régulation du
comportement et suggère que le maintien d’un comportement est le résultat du niveau de
motivation autodéterminée d’un individu (Deci & Ryan, 1985; Ryan & Deci, 2000). Des
études ont démontré qu’un comportement régulé via une motivation autodéterminée
favorise le maintien de saines habitudes alimentaires à long terme (Pelletier et al., 2004;
Williams et al., 1996). Le succès d’une intervention nutritionnelle à long terme pourrait
ainsi reposer en partie sur la place accordée aux facteurs de motivation de l’individu. Le fait
d’impliquer activement la personne dans le choix des changements alimentaires ainsi que
des stratégies pour réaliser les changements, dans un contexte d’intervention soutenant la
motivation autodéterminée, pourrait favoriser l’adoption et le maintien de saines habitudes
alimentaires. D’autre part, les différences interindividuelles peuvent influencer la capacité
d’adhérer aux recommandations alimentaires dans le contexte d’une intervention. À cet
égard, des différences entre les hommes et les femmes sont rapportées dans la littérature en
lien avec les habitudes et comportements alimentaires (Arganini, 2012; Garriguet, 2009).
Afin de développer des interventions nutritionnelles optimales, il s’avère impératif de
déterminer si des différences associées au genre, pouvant se traduire par des
comportements et motivations différentes à l’égard de l’alimentation et de la santé, et
requérant des approches nutritionnelles adaptées à ces besoins différents, influencent la
réponse à une intervention nutritionnelle. Cette éventualité a certainement un fort potentiel
pour améliorer la pertinence des conseils nutritionnels prodigués aux hommes et aux
femmes.
Jusqu’à présent, peu d’études ont comparé les effets d’un programme d’éducation en
nutrition visant l’adoption de l’alimentation méditerranéenne entre les hommes et les
femmes, et aucune n’a examiné l’impact de facteurs reliés à la motivation autodéterminée
sur les différences entre les hommes et les femmes dans la réponse à une intervention
nutritionnelle. L’objectif général des travaux présentés dans cette thèse visait à déterminer
les différences entre les hommes et les femmes dans leur réponse à un programme
2
d’éducation en nutrition de 12 semaines visant l’adoption d’une alimentation de type
méditerranéen et basé sur la théorie de l’autodétermination, plus spécifiquement en termes
de changements alimentaires, anthropométriques, métaboliques et liés à la qualité de vie.
3
CHAPITRE 1 :
Revue de littérature
5
1.1 Prévalence des maladies cardiovasculaires au Canada
Les maladies cardiovasculaires (MCV) regroupent diverses maladies affectant le système
circulatoire, notamment le cœur et les vaisseaux sanguins (Agence de la santé publique du
Canada, 2015). Ces maladies représentent l’une des principales causes de décès au Canada,
soit près de 21% de tous les décès (Agence de la santé publique du Canada, 2015). Bien
que le taux de mortalité attribuable aux MCV ait diminué de façon importante dans les
dernières décennies, possiblement dû en partie à une meilleure prise en charge des facteurs
de risque (Agence de la santé publique du Canada, 2015), on rapporte malgré tout que neuf
Canadiens sur dix présentent au minimum un facteur de risque associé au développement
de MCV alors que 40% présentent un minimum de trois facteurs de risque (Agence de la
santé publique du Canada, 2009). À ce propos, il est bien documenté que l’association de
plusieurs facteurs de risque a un effet synergique sur le risque global et prédispose
davantage une personne à développer une MCV (Grundy et al., 2005; Yusuf et al., 2004).
Certains facteurs de risque associés à ces maladies ne peuvent être modifiés par des
interventions, tels que le sexe masculin, l’âge avancé et les antécédents familiaux de MCV
prématurées (Anderson et al., 2013). Toutefois, la majorité des facteurs de risque sont
modifiables par l’adoption de saines habitudes de vie ou par un traitement
pharmacologique, et constituent ainsi des cibles d’intervention appropriées dans la
prévention de MCV (Anderson et al., 2013). Les facteurs de risque modifiables incluent les
dyslipidémies, le diabète de type 2, l’hypertension artérielle, l’obésité abdominale, le
tabagisme, le stress, la sédentarité et une alimentation de faible qualité (Agence de la santé
publique du Canada, 2009; Bonora, 2006; Schaefer, 2002). Par ailleurs, chez les adultes
d’âge moyen, des différences entre les hommes et les femmes sont rapportées quant à la
prévalence de certains facteurs de risque (Tan et al., 2010), avec une proportion plus élevée
d’hommes présentant une hypertension artérielle, une dyslipidémie ou une obésité
abdominale (Pilote et al., 2007; Scarsella et al., 2003; Williams, 2004). D’autre part, des
données indiquent que la présence de diabète contribue davantage au risque de MCV chez
les femmes que chez les hommes (Peters et al., 2014; Pilote et al., 2007).
7
Selon les lignes directrices canadiennes, les interventions liées au mode de vie demeurent la
pierre angulaire de la prévention de MCV (Anderson et al., 2013). Globalement, les
recommandations visent l’amélioration des habitudes alimentaires, l’augmentation de la
pratique d’activité physique, une consommation d’alcool modérée, l’abandon du tabagisme
et la prise en charge des facteurs de stress psychologique (Anderson et al., 2013). Sur le
plan des recommandations nutritionnelles plus spécifiquement (Tableau 1), on encourage
une approche hypocalorique s’il y a présence d’embonpoint ou d’obésité, et en ce qui
concerne les changements alimentaires, l’accent est mis sur les aliments et les modes
alimentaires à privilégier plutôt que sur les restrictions.
Tableau 1. Recommandations nutritionnelles canadiennes visant la prévention des
maladies cardiovasculaires (2013)

Restriction calorique visant à atteindre et maintenir un poids santé.

Favoriser les acides gras polyinsaturés et monoinsaturés, incluant les acides
gras oméga-3 (provenant principalement du poisson), en remplacement des
acides gras trans et saturés.

Limiter les apports en lipides totaux à < 30% de l’apport énergétique
quotidien.

Limiter le cholestérol alimentaire à 200 mg/jour chez les personnes atteintes
de dyslipidémies ou présentant un risque cardiovasculaire élevé.

Augmenter les apports en fruits, en légumes et en produits céréaliers à grains
entiers.

Augmenter les apports en fibres alimentaires à > 30 g/jour.

Diminuer les apports en sucres simples.

Diminuer les apports en sodium.

Les modes alimentaires Méditerranéen, Portfolio ou DASH (Dietary
Approach to Stop Hypertension) sont recommandés pour améliorer le profil
lipidique ou réduire le risque cardiovasculaire.

Augmenter la consommation d’aliments enrichis en phytostérols, de fibres
solubles, du soya et des noix pour diminuer le cholestérol plasmatique.
Vu la prévalence considérablement élevée des facteurs de risque dans la population et
l’importance accordée à l’amélioration des habitudes alimentaires dans le contexte de la
prévention de MCV, des efforts doivent être déployés afin de développer des interventions
8
adaptées aux besoins des personnes et qui favoriseront une meilleure observance des
recommandations alimentaires. Pour ce faire, il importe d’abord d’examiner les principaux
modèles de saine alimentation proposés.
1.2 Modèles de saine alimentation proposés dans la littérature
1.2.1 Évaluation des habitudes alimentaires plutôt que les apports en nutriments
Au cours des dernières décennies, plusieurs chercheurs ont recommandé d’évaluer
l’alimentation des individus à partir des habitudes alimentaires ou de groupes d’aliments
(Freeland-Graves & Nitzke, 2013; Hu, 2008; Kant, 1996), plutôt que d’évaluer les apports
en certains nutriments spécifiques. L’un des principaux arguments proposés s’explique par
le fait qu’il s’agit d’une méthode plus représentative des habitudes alimentaires réelles des
individus. En effet, ceux-ci ne consomment pas de nutriments de façon isolée, mais bien
des repas composés d’une variété d’aliments (Hu, 2002). De plus, l’évaluation de
l’alimentation à partir de groupes d’aliments permet de considérer l’effet synergique
potentiel de la combinaison des nutriments présents dans un même aliment (Hu, 2002). Ces
éléments soutiennent la pertinence de considérer les habitudes alimentaires afin d’obtenir
un portrait plus complet de la qualité de l’alimentation, et ainsi pouvoir mieux prédire
l’impact de l’alimentation sur la santé.
Plusieurs modèles de saine alimentation sont proposés dans la littérature. Certains de ces
modèles sont définis théoriquement à partir de recommandations alimentaires émises par
des organismes de santé publique alors que d’autres sont plutôt créés à partir de données
empiriques, provenant généralement d’enquêtes menées dans les populations (Waijers et
al., 2007). Dans le cadre de cette thèse, l’objectif n’est pas de dresser une liste exhaustive
des modèles existants, mais plutôt de présenter les plus fréquemment cités dans la
littérature afin de mettre en lumière notre choix d’avoir recours au modèle de l’alimentation
méditerranéenne dans notre intervention.
9
1.2.2 Régime DASH
Le régime Dietary Approaches to Stop Hypertension (DASH) est principalement reconnu
pour ses effets bénéfiques sur la tension artérielle auprès d’adultes hypertendus et
normotendus (Fung et al., 2008; Sacks et al., 2001) ainsi que sur les concentrations de CLDL (Obarzanek et al., 2001). L’adhésion à un régime de type DASH a également été
associée à une diminution du risque de MCV (Fung et al., 2008; Schwingshackl &
Hoffmann, 2015). Ce sont les bienfaits reconnus de ce régime sur la santé qui en font
maintenant un modèle de saine alimentation couramment utilisé. Ce régime se décrit
comme une alimentation riche en fruits, légumes, noix et légumineuses et produits laitiers
faibles en matières grasses, par une consommation prédominante de grains entiers, par une
faible consommation de viandes rouges et de viandes transformées, et par des apports
limités en acides gras saturés (Karanja et al., 1999). Les recommandations liées au nombre
de portions à consommer dans chacun des groupes d’aliments varient selon les besoins
énergétiques quotidiens des individus (National Heart, Lung, and Blood Institute, 2006).
1.2.3 Profil de type Prudent
Contrairement au modèle d’alimentation précédent, le profil alimentaire de type Prudent
constitue un modèle dont les composantes sont définies selon la population étudiée. En
effet, les profils alimentaires sont généralement définis à l’aide d’une forme d’analyse
factorielle exploratoire, soit l’analyse en composantes principales (Newby & Tucker,
2004). Brièvement, cette analyse identifie les profils alimentaires auprès d'une population à
l'aide de l'information nutritionnelle, souvent rapportée par un questionnaire de fréquence
alimentaire ou un journal alimentaire (Hu et al., 2000). L’analyse en composantes
principales a pour but de former de plus petits groupes de variables corrélées, sans toutefois
être corrélés les uns aux autres. Il s’agit donc d’un regroupement d'aliments basé sur le
degré de corrélation existant entre ces aliments. Les profils alimentaires générés
représentent la combinaison d'aliments consommés par les individus inclus dans
l’échantillon (Hu et al., 2000). Les profils sont nommés de façon qualitative selon la
10
composition des aliments qu’ils incluent et permettent de comparer des personnes entre
elles selon leurs apports alimentaires (Newby & Tucker, 2004).
Un profil alimentaire de type Prudent regroupe des apports alimentaires sains et se
caractérise généralement par une consommation élevée de légumes, fruits, légumineuses,
grains entiers, poisson et fruits de mer, et de volaille (Hu et al., 1999). Dans la littérature,
ce profil est souvent comparé à un profil alimentaire moins sain, soit le profil de type
Western, généralement caractérisé par une consommation élevée de viandes rouges et
viandes transformées, beurre, produits laitiers riches en matières grasses, d’œufs et de
grains raffinés (Hu et al., 1999). Une particularité des profils alimentaires s’explique par le
fait que chaque personne se voit attribuer un score global pour chacun des profils générés
(Hu et al., 2000). Par exemple, une personne peut présenter un score élevé à la fois pour le
profil Prudent et le profil Western. Dans l’optique d’évaluer l’impact de la qualité
alimentaire sur la santé, il peut s’avérer pertinent de procéder à l’analyse de plusieurs
profils alimentaires simultanément. Quoiqu’il en soit, plusieurs auteurs ont mis en relation
divers profils alimentaires, dont le profil de type Prudent, avec certains facteurs de risque
pour la santé. Des études ont montré que le profil Prudent était inversement associé au
risque de MCV, chez les hommes (Hu et al., 2000) et chez les femmes (Fung et al., 2001).
1.2.4 Guide alimentaire canadien
Le Guide alimentaire canadien (GAC) définit la saine alimentation auprès de la population
canadienne (Santé Canada, 2007). Ce modèle d’alimentation regroupe les recommandations
visant à combler les besoins nutritionnels des Canadiens et des Canadiennes, à diminuer le
risque de développer l’obésité et diverses maladies chroniques telles que le diabète de type
2, les MCV, certains cancers et l’ostéoporose, et à permettre d’atteindre un état de santé
global et de bien-être. Le GAC souligne également l’importance de combiner une saine
alimentation à un mode de vie actif.
11
Les recommandations alimentaires formulées dans le GAC proposent les quantités
d’aliments permettant de répondre aux besoins des individus de même que le type
d’aliments qui font partie d’une saine alimentation (Santé Canada, 2007). Ce modèle
alimentaire présente les aliments selon quatre groupes différents, soit Légumes et fruits,
Produits céréaliers, Laits et substituts et Viandes et substituts. De plus, il respecte les
normes nutritionnelles se rapportant aux Apports nutritionnels de référence et tient compte
de l’Étendue des valeurs acceptables pour les macronutriments fixée pour les glucides,
protéines et les lipides. Le nombre de portions recommandé pour chacun des groupes
alimentaires varie en fonction du sexe et de l’âge, ou de l’étape de la vie des individus.
Dans ses recommandations, le GAC souligne également l’importance de savourer une
variété d’aliments provenant des quatre groupes alimentaires (Tableau 2).
12
Tableau 2. Types d'aliments à privilégier selon le Guide alimentaire canadien
Légumes et fruits
Consommer au minimum un légume vert foncé et un légume orangé chaque jour.
Choisir des légumes et des fruits préparés avec peu ou pas de matières grasses,
sucre ou sel.
Consommer des légumes et des fruits entiers de préférence aux jus.
Produits céréaliers
Consommer au minimum la moitié des portions de produits céréaliers sous forme
de grains entiers.
Choisir des produits céréaliers plus faibles en lipides, sucre ou sel.
Laits et substituts
Boire chaque jour du lait écrémé ou du lait contenant 1% ou 2% de matières
grasses.
Choisir des substituts du lait plus faibles en matières grasses.
Viandes et substituts
Consommer régulièrement des substituts de la viande (ex : légumineuses, tofu).
Consommer au minimum deux portions de poisson chaque semaine.
Choisir des viandes maigres ou des substituts préparés avec peu ou pas de
matières grasses ni de sel.
Autres recommandations
Consommer une petite quantité de lipides insaturés chaque jour.
Boire de l’eau pour étancher la soif.
Limiter la consommation d’aliments et de boissons riches en calories, lipides,
sucre et sel.
Choisir des viandes maigres ou des substituts préparés avec peu ou pas de
matières grasses ni de sel.
13
1.2.5 Régime méditerranéen
Le régime méditerranéen fait référence au mode alimentaire adopté par les populations des
pays bordant la mer Méditerranée, plus particulièrement la Grèce, la région de la Crête et le
sud de l’Italie, dans les années 1960 (Willett et al., 1995). L’intérêt envers le régime
méditerranéen comme modèle de saine alimentation a pris tout son sens dans le cadre de la
Seven Countries Study (Keys, 1970). Cette étude de grande envergure menée par Keys et
al. visait à étudier le risque de MCV auprès de 16 cohortes provenant de divers pays dans le
monde entier. Les résultats de leur étude ont permis de constater que l’incidence de MCV
était plus faible chez les populations vivant dans les régions entourant la mer Méditerranée
que dans les pays au nord de l’Europe et en Amérique du Nord (Keys et al., 1986). De plus,
les populations méditerranéennes présentaient une espérance de vie plus longue et un taux
de mortalité plus faible relié aux MCV et à certains cancers comparativement à plusieurs
autres pays dans le monde (Keys et al., 1986; World Health Organization, 1993).
À cette époque, malgré certaines différences dans les habitudes alimentaires des
populations méditerranéennes, leur alimentation présentait plusieurs caractéristiques
communes quant aux groupes d’aliments et à leur importance dans l’alimentation,
notamment la prédominance de l’huile d’olive (Trichopoulou & Lagiou, 1997; Willett,
1994; Willett et al., 1995). L’alimentation méditerranéenne traditionnelle se distingue par
l’importance accordée à la présence de produits végétaux, d’huile d’olive et d’aliments
frais, cultivés localement et peu transformés (Willett et al., 1995). Plus spécifiquement,
l’alimentation méditerranéenne traditionnelle est caractérisée par une consommation
abondante de fruits, légumes, céréales entières, noix et légumineuses, par une
consommation modérée de poissons, volailles et de produits laitiers, principalement sous la
forme de yogourt et de fromage, puis par une faible consommation de viandes rouges et de
sucreries (Giugliano & Esposito, 2005; Trichopoulou & Lagiou, 1997; Willett et al., 1995).
L’huile d’olive constitue la principale source de matières grasses ajoutées. Le vin est
consommé de façon modérée et généralement lors des repas (Giugliano & Esposito, 2005;
Willett et al., 1995). Cette alimentation fournit ainsi des apports importants en fibres
alimentaires, acides gras oméga-3, phytostérols, vitamines, minéraux et en antioxydants
14
(Willett et al., 1995). Par ailleurs, l’apport en lipides est plutôt élevé et très variable selon le
pays dont il est question, variant d’environ 30% en Italie à plus de 40% en Grèce, mais
procure toutefois un faible apport en acides gras saturés (environ 7 à 8% de l’apport
énergétique) (Trichopoulou & Lagiou, 1997; Willett et al., 1995).
Le régime méditerranéen a été illustré sous la forme d’une pyramide (Figure 1) afin de
représenter visuellement les proportions relatives et les fréquences de consommation des
aliments et groupes d’aliments contribuant à ce modèle de saine alimentation (Willett et al.,
1995). Il importe toutefois de mentionner que la pyramide méditerranéenne vise à
représenter les choix alimentaires sains, plutôt que de définir des recommandations
spécifiques quant à la quantité d’aliments à consommer (Willett et al., 1995).
Figure 1. Pyramide de l'alimentation méditerranéenne traditionnelle. © 2009 Oldways
Preservation & Exchange Trust. Tirée de www.oldwayspt.org (Middleton, 2009).
15
Des études ont démontré que l’alimentation méditerranéenne considérée dans son ensemble
aurait un impact plus important sur la santé cardiovasculaire que la somme des effets isolés
de chacune de ses composantes (de Lorgeril et al., 1999; Trichopoulou et al., 2003).
L’alimentation méditerranéenne constitue donc une référence en matière de saine
alimentation (Sofi et al., 2014). En plus de ses bienfaits sur la santé, ce mode alimentaire
est composé d’une grande diversité d’aliments savoureux, et où les aspects de convivialité,
plaisir et bien-être entourant la consommation des aliments s’avèrent des principes
fondamentaux (Willett et al., 1995). Enfin, en plus de promouvoir de saines habitudes
alimentaires, ce modèle soutient l’importance d’être physiquement actif sur une base
régulière (Willett et al., 1995). Dans sa globalité, le régime méditerranéen constitue ainsi
un mode de vie sain.
En résumé, tous les modèles d’alimentation présentés dans cette section partagent des
points communs. En effet, ils accordent tous une place importante à la consommation de
fruits et légumes, de produits céréaliers à grains entiers, de protéines de source végétale, de
produits laitiers faibles en matières grasses, d’huiles végétales insaturées et suggèrent de
limiter les sources de gras saturés et la consommation de sucreries. Certaines études ont
démontré que l’adhésion à ces modèles de saine alimentation est associée à plusieurs
bienfaits sur la santé, notamment sur la santé cardiovasculaire (Hu, 2008; Schwingshackl &
Hoffmann, 2015; Sofi et al., 2014). Cependant, on constate que le régime méditerranéen
traditionnel constitue pour sa part plus qu’un simple modèle de saine alimentation, il
s’avère un mode de vie en soi. Les principes relatifs au régime méditerranéen en font un
modèle particulièrement intéressant dans le contexte d’interventions nutritionnelles visant
la prévention des MCV.
1.2.6 Méthodes permettant de calculer un score d’adhésion aux différents modèles
de saine alimentation
Pour la majorité des modèles d’alimentation, il est possible de calculer un score d’adhésion
reflétant la qualité globale de l’alimentation. En général, le score est développé en
accordant un pointage à la consommation de différents aliments, groupes d’aliments ou
16
d’une combinaison d’aliments et de nutriments caractérisant le modèle alimentaire. Par
exemple, le Healthy eating index constitue un score reflétant la qualité de l’alimentation
développé afin d’évaluer le niveau de concordance des apports alimentaires selon les
recommandations alimentaires du GAC (Garriguet, 2009).
En ce qui concerne plus spécifiquement l’adhésion à l’alimentation méditerranéenne,
plusieurs scores sont proposés dans la littérature (Beunza et al., 2010; Estruch et al., 2006).
Il demeure que pour la plupart, un score d’adhésion plus élevé se traduit par une
alimentation plus saine. Une des méthodes les plus fréquemment utilisées est celle des
scores méditerranéens où les médianes de consommation des aliments et nutriments ciblés
par le score dans une population donnée sont utilisées afin de déterminer le nombre de
points accordés à une personne (Bach et al., 2006). Plus spécifiquement, cette personne
reçoit un point lorsque sa consommation d’un aliment ou nutriment retrouvé dans
l’alimentation méditerranéenne est supérieure à la médiane de la population de référence. À
l’inverse, pour un aliment ou nutriment rarement consommé selon le mode alimentaire
méditerranéen, la personne reçoit un point lorsque sa consommation est inférieure à la
médiane. Une limite à l’utilisation des médianes de consommation des aliments et
nutriments s’explique par le fait que le niveau d’adhésion à l’alimentation méditerranéenne
d’un individu peut être comparé à celui d’une population donnée, sans toutefois
nécessairement
refléter
le
niveau
d’adhésion
à
l’alimentation
méditerranéenne
traditionnelle. Une autre méthode permettant d’évaluer le niveau d’adhésion au mode
alimentaire méditerranéen consiste à baser le score méditerranéen sur la pyramide
méditerranéenne traditionnelle où un score est accordé à chaque composante de la pyramide
selon une méthode préétablie (Bach et al., 2006). Cette méthode est généralement
préconisée dans le contexte d’études d’intervention puisqu’elle permet de mieux quantifier
le niveau d’adhésion des individus à l’alimentation méditerranéenne traditionnelle, et
permet par le fait même d’évaluer la qualité globale de l’alimentation. De plus, ce type de
scores méditerranéens permet de déterminer plus facilement l’impact réel de l’alimentation
sur différentes variables liées à la santé, par exemple la prévalence de MCV et ses facteurs
de risque (Sofi et al., 2014).
17
Un score d’adhésion à l’alimentation méditerranéenne (score Med) a été développé dans la
population québécoise et peut être calculé à partir des apports alimentaires rapportés via un
questionnaire de fréquence alimentaire (Goulet et al., 2003). Ce score Med inclut 11
composantes, soit les produits céréaliers, les légumes, les fruits, les légumineuses, noix et
graines, l’huile d’olive, les produits laitiers, les poissons et fruits de mer, les volailles, les
œufs, les viandes rouges et viandes transformées, et les sucreries (voir en Annexe pour plus
de détails). Un score variant de 0 à 4 est attribué à chacune des onze composantes de la
pyramide méditerranéenne. Pour les groupes d’aliments situés à la base de la pyramide
(p.ex. : légumineuses), un score élevé reflète une consommation élevée. Au contraire, pour
les groupes d’aliments retrouvés aux niveaux supérieurs de la pyramide (p.ex. : viande
rouge), un score élevé est plutôt attribué à une faible consommation de ces aliments. Le
score Med peut varier entre 0 et 44 points (Goulet et al., 2003).
Dans le cadre des travaux présentés dans cette thèse, nous avons choisi le mode alimentaire
méditerranéen à titre de modèle de saine alimentation. De plus, nous avons eu recours à ce
score Med afin d’évaluer le niveau d’adhésion à l’alimentation méditerranéenne et de le
mettre en relation avec différents bienfaits associés à ce type d’alimentation.
1.3 Bienfaits de l’alimentation méditerranéenne
1.3.1 Bienfaits sur la santé
Les bienfaits de l’alimentation méditerranéenne sur la santé et sur la longévité ont
clairement été démontrés par une récente méta-analyse incluant plusieurs études de
cohortes prospectives et regroupant plus de deux millions d’individus (Sofi et al., 2014).
Plus précisément, les résultats de cette étude indiquent que l’adhésion à l’alimentation
méditerranéenne est associée à une diminution du taux de mortalité toutes causes
confondues, à des diminutions de l’incidence et de la mortalité liées aux MCV et aux
cancers, ainsi qu’à une incidence plus faible de maladies neuro-dégénératives (Sofi et al.,
2014). Cette méta-analyse appuie ainsi de façon robuste les effets favorables de
l’alimentation méditerranéenne en prévention primaire et secondaire des MCV.
18
Par ailleurs, l’étude PREDIMED, soit la plus importante étude d’intervention randomisée et
contrôlée visant à évaluer les effets de l’alimentation méditerranéenne en prévention
primaire de MCV, a récemment permis de confirmer le rôle protecteur de l’alimentation
méditerranéenne sur la santé cardiovasculaire auprès de 7447 hommes et femmes espagnols
présentant un risque élevé de MCV (Estruch et al., 2013). Cette étude menée sur une
période de 4 ans avait pour but de comparer les effets d’un régime méditerranéen
supplémenté en huile d’olive ou en noix à une alimentation faible en lipides (groupe
témoin) sur le risque d’événements coronariens. Les résultats ont démontré une diminution
du risque relatif d’environ 30 % des événements cardiovasculaires majeurs (infarctus,
accidents vasculaires cérébraux, mortalité cardiovasculaire) chez les sujets randomisés au
régime méditerranéen supplémenté en huile d’olive ou en noix, comparativement au groupe
témoin (Estruch et al., 2013).
Les effets favorables de l’alimentation méditerranéenne ont aussi été documentés pour
d’autres problématiques de santé telles que les dyslipidémies, l’inflammation,
l’hypertension artérielle, la régulation du poids corporel, l’incidence et le traitement du
diabète de type 2, soit toutes des conditions prédisposant aux MCV.
Plusieurs études soutiennent les bienfaits de l’alimentation méditerranéenne sur le profil
lipidique, principalement par une augmentation des concentrations de C-HDL et une
diminution des triglycérides, et également sur la tension artérielle, la résistance à l’insuline
et des marqueurs sériques liés à l’inflammation (Grosso et al., 2014; Kastorini et al., 2011).
Bien que certaines études ne rapportent pas de relation entre l’adhésion à l’alimentation
méditerranéenne et la diminution de la prévalence de l’obésité (Trichopoulou et al., 2005;
Sanchez-Villegas et al., 2006; Estruch et al., 2006) plusieurs ont démontré des effets
positifs sur la régulation du poids corporel se traduisant par une diminution du gain de
poids (Buckland et al., 2008), ou une perte de poids (Buckland et al., 2008; Esposito et al.,
2011). Dans le même sens, certains travaux ont montré qu’une meilleure adhésion à
l’alimentation méditerranéenne était associée à une circonférence de la taille plus faible
19
(Kastorini et al., 2011; Romaguera et al., 2009; Trichopoulou et al., 2005). Par ailleurs,
aucune étude n’a rapporté que l’adhésion à l’alimentation méditerranéenne favoriserait un
gain de poids (Buckland et al., 2008; Esposito et al., 2011). Les effets physiologiques de
certaines composantes de l’alimentation méditerranéenne pourraient expliquer l’impact
positif sur la régulation du poids (Buckland et al., 2008). En effet, la présence abondante
d’aliments de source végétale favorise une consommation élevée de fibres alimentaires,
reconnues pour leur effet favorable sur la satiété, et pourrait contribuer à diminuer la
densité énergétique de l’apport alimentaire global (Buckland et al., 2008). La
consommation régulière d’aliments à la fois savoureux et rassasiants, par exemple les noix,
pourrait également favoriser une meilleure régulation du poids (McManus et al., 2001).
Enfin, certains travaux suggèrent que la consommation prédominante d’huile d’olive
(acides gras monoinsaturés) pourrait favoriser l'oxydation des substrats énergétiques via
une amélioration du métabolisme du glucose, une thermogenèse induite par l’alimentation
augmentée ainsi qu’une dépense énergétique quotidienne totale plus élevée, en
comparaison avec une alimentation plus riche en acides gras saturés (Buckland et al.,
2008).
Ce type d’alimentation aurait également des effets bénéfiques dans la prévention et le
traitement du diabète de type 2. Une récente méta-analyse rapporte qu’une meilleure
adhésion à ce mode alimentaire est associée à une diminution de 23% du risque de
développer le diabète de type 2 (Koloverou et al., 2014). Des études indiquent que
l’adhésion à cette alimentation permettrait également une meilleure prise en charge du
diabète, notamment par un meilleur contrôle glycémique et une amélioration de la
sensibilité à l’insuline (Ajala et al., 2013; Estruch et al., 2006). D’autre part, l’obésité, plus
particulièrement l’obésité abdominale, constitue un facteur de risque important dans le
développement du diabète de type 2 (Hu et al., 2001; Wang et al., 2005). Comme certaines
études ont démontré que l’adhésion à l’alimentation méditerranéenne peut avoir des effets
favorables sur le poids, ce mécanisme peut aussi contribuer à expliquer le rôle protecteur de
ce mode alimentaire sur le risque de diabète de type 2 (Buckland et al., 2008; Schroder,
2007).
20
En résumé, l’alimentation méditerranéenne est associée à plusieurs bienfaits sur la santé et
son rôle protecteur dans la prévention de MCV est maintenant établi avec le niveau le plus
élevé d’évidence scientifique.
1.3.2 Bienfaits sur la qualité de vie
L’alimentation méditerranéenne a également été associée à la perception d’une meilleure
santé physique et mentale, plus précisément dans les populations méditerranéennes
(Henriquez Sanchez et al., 2012; Landaeta-Diaz et al., 2013; Munoz et al., 2009). Selon
une étude transversale, l’adhésion à l’alimentation méditerranéenne est associée à la
perception d’une meilleure qualité de vie relative à la santé, chez les hommes et les femmes
(Munoz et al., 2009). L’étude de Henriquez Sanchez et al. appuie ces résultats en
démontrant des associations positives entre l’adhésion à l’alimentation méditerranéenne et
certains aspects physiques (fonctionnement physique, limites liées à la santé physique,
tolérance à la douleur physique, santé générale) et mentaux (limites liées aux émotions,
vitalité, fonctionnement social) reliés à la qualité de vie (Henriquez Sanchez et al., 2012).
De plus, leurs résultats indiquent qu’une adhésion élevée à cette alimentation au départ ou
une augmentation de l’adhésion durant le suivi serait associée à une meilleure qualité de vie
physique (fonctionnement physique, santé générale) et mentale (vitalité). Les auteurs
soulignent toutefois une limite importante à l’égard de leur étude, soit le fait que la qualité
de vie ait été évaluée seulement après le suivi de 4 ans. Par conséquent, la relation suggérée
entre l’adhésion à l’alimentation méditerranéenne et la qualité de vie ne permet pas de
considérer le niveau de qualité de vie des individus au départ (Henriquez Sanchez et al.,
2012).
Divers mécanismes sont suggérés afin d’expliquer l’impact positif de l’alimentation
méditerranéenne sur la qualité de vie, notamment les effets favorables de cette alimentation
sur le risque de maladies chroniques et sur les facteurs de risque qui y sont associés
(Martinez-Gonzalez et al., 2008; Martinez-Gonzalez et al., 2011; Sanchez-Villegas et al.,
2006). L’adhésion à l’alimentation méditerranéenne a aussi été associée à une meilleure
santé mentale, plus précisément par ses effets protecteurs sur le risque de développer des
21
maladies dégénératives ou des désordres mentaux, et sur le risque de déclin cognitif
(Engelhart et al., 2002; Sanchez-Villegas et al., 2009; Sofi et al., 2010).
En définitive, la littérature supporte les bienfaits de l’alimentation méditerranéenne sur la
santé, mais également sur la qualité de vie des individus. Une fois de plus, ceci témoigne de
la pertinence d’avoir recours à ce modèle d’alimentation en vue de préserver une santé et
un bien-être optimaux.
1.4 Déterminants des choix alimentaires sains
Bien que l’adoption de saines habitudes alimentaires puisse contribuer à un meilleur état de
santé, plusieurs facteurs provenant de l’environnement et liés à l’individu sont susceptibles
d’influencer les choix alimentaires, et peuvent ainsi influencer le potentiel d’adhérer à des
recommandations alimentaires en vue d’améliorer la santé (Brug et al., 2008).
Les choix alimentaires sont motivés par des attributs d’ordre individuel qui se situent dans
le contexte plus large de facteurs familiaux, sociaux, culturels, économiques, politiques et
physiques (Raine, 2005). Parmi les déterminants collectifs de la saine alimentation,
mentionnons l’étiquetage nutritionnel, un environnement favorable à la disponibilité et
l’accessibilité des aliments sains à coût abordable, les messages publicitaires ainsi que les
habitudes et comportements alimentaires de l’entourage de l’individu, par exemple la
famille, les amis et les collègues (Raine, 2005). Les choix alimentaires d’une personne sont
également influencés par des déterminants individuels. À cet égard, la motivation est
reconnue comme un concept central impliqué dans le processus de choix alimentaires sains
(Guillaumie et al., 2010), et sera abordée plus en détails à la section 1.7.3. D’autres facteurs
individuels peuvent se rapporter à la génétique, l’état physiologique (p.ex., la faim),
l’expérience personnelle à l’égard des aliments (p.ex., les préférences alimentaires), aux
connaissances, perceptions et croyances à l’égard de la saine alimentation et à la
préoccupation reliée au poids et à l’image corporelle (Drewnowski, 1997; Freeland-Graves
& Nitzke, 2013; Raine, 2005). Ces déterminants peuvent aussi interagir avec certaines
22
caractéristiques sociodémographiques, incluant l’âge, le niveau d’éducation et le genre
(Henson et al., 2010).
Tous ces facteurs peuvent influencer les choix alimentaires et par conséquent favoriser ou
non une saine alimentation. Cependant, dans l’optique de mieux comprendre les différences
interindividuelles dans la réponse à une intervention nutritionnelle visant à améliorer la
santé, une attention particulière doit être accordée aux déterminants individuels. Parmi les
facteurs mentionnés précédemment, le genre ressort comme un aspect important. Afin de
mieux comprendre l’implication du genre dans le contexte de l’alimentation, il importe
d’abord de définir plus clairement ce concept.
1.4.1 Définition des concepts de genre et de sexe
Depuis quelques années, un intérêt de plus en plus important est accordé aux différences
entre les hommes et les femmes dans les domaines de la santé et de l’alimentation (Cornier
et al., 2010; Shi et al., 2009; Stevens et al., 2010). Plusieurs arguments soutiennent
l’importance de considérer les différences entre les hommes et les femmes dans le domaine
de la santé lorsque l’on s’intéresse aux variations interindividuelles, notamment afin
d’améliorer la qualité des travaux scientifiques au point de vue de la validité, de la fiabilité
et de la généralisation des résultats d’études (Institute of Gender and Health, 2012).
Cependant, dans un tel contexte, il importe de distinguer les différences sexuelles des
différences relatives au genre lorsque l’on compare les hommes et les femmes.
Globalement, le sexe et le genre sont deux concepts fortement liés entre eux, mais toutefois
distincts (Institute of Gender and Health, 2012). Actuellement, une limite importante dans
la littérature se traduit par une utilisation de ces deux concepts de façon interchangeable,
possiblement en raison d’une mauvaise compréhension de leur définition respective. Le
genre réfère aux rapports socialement construits, traits de personnalité, attitudes,
comportements, valeurs, puissance relative et influence que la société attribue aux hommes
et aux femmes. Pour sa part, le sexe se définit comme un construit biologique regroupant
23
les variations anatomiques, physiologiques, génétiques et hormonales existant entre les
espèces.
Dans une perspective de préciser le réel impact de l’adhésion à des recommandations
alimentaires sur la santé, les différences relatives au genre et au sexe ont avantage à être
considérées.
1.4.2 Différences relatives au genre quant aux habitudes et comportements
alimentaires
De façon générale, les femmes rapportent une meilleure qualité alimentaire que les hommes
(Garriguet, 2009; Liebman et al., 2006). Selon la littérature, les femmes ont une
consommation plus élevée de fruits et légumes, aliments riches en fibres alimentaires et
faibles en lipides, et consomment moins de viandes rouges, d’alcool et de boissons
gazeuses que les hommes (Arganini, 2012; Kiefer et al., 2005; Li et al., 2000; Liebman et
al., 2001).
Plusieurs études indiquent que les hommes et les femmes présentent aussi des
caractéristiques différentes liées à leurs attitudes et croyances à l’égard de l’alimentation et
de la santé (Arganini, 2012; Beardsworth, 2002; Wardle et al., 2004). En effet, les hommes
accorderaient moins d’importance à l’adoption d’une saine alimentation comparativement
aux femmes (Courtenay et al., 2002; Wardle et al., 1997), et il est à noter que cette
tendance a été observée dans plusieurs pays à travers le monde (Wardle et al., 2004). De
plus, les hommes semblent attribuer une priorité moindre à la santé dans le processus de
choix alimentaires en comparaison à d’autres éléments tels que les saveurs et la commodité
des aliments (Fagerli & Wandel, 1999; Steptoe et al., 2002; Wardle et al., 2004), et
affirment être davantage ambivalents face à des choix alimentaires sains en comparaison
avec les femmes (Povey et al., 2001; Sparks et al., 2001). D’autres études ont démontré que
les femmes ont une attitude plus positive à l’égard de l’alimentation, sont plus susceptibles
de se mettre en action afin d’améliorer leurs habitudes alimentaires, rapportent un niveau de
connaissances en nutrition plus élevé et affirment lire davantage les étiquettes
24
nutritionnelles comparativement aux hommes (Baker & Wardle, 2003; Goodman et al.,
2011; Krukowski et al., 2006). Par ailleurs, des données indiquent qu’une proportion plus
importante de femmes que d’hommes rapportent faire des efforts afin d’avoir des apports
alimentaires concordant avec les recommandations alimentaires. Les différences entre les
hommes et les femmes liées aux attitudes et croyances à l’égard de l’alimentation sont donc
susceptibles d’expliquer en partie les différences relatives au genre observées dans les
habitudes alimentaires (Wardle et al., 2004).
Les différents rôles sociaux et responsabilités attribués aux hommes et aux femmes dans la
société peuvent aussi sans doute expliquer les différences notées entre les hommes et les
femmes dans le contexte de l’alimentation. Les femmes sont plus nombreuses que les
hommes à être en charge de l’achat et de la préparation des repas sur une base régulière
(Beardsworth, 2002). De plus, davantage de femmes que d’hommes se considèrent
compétents pour cuisiner à partir d’ingrédients de base (Beardsworth, 2002).
Un autre aspect important à considérer est la préoccupation reliée au poids et à
l’alimentation. À cet égard, on constate qu’une proportion plus élevée de femmes que
d’hommes affirment faire des efforts afin de contrôler leur poids en modifiant leur
alimentation (Johnson & Bedford, 2004; Wardle et al., 2004). Considérant que les diètes
visent typiquement la perte de poids en amenant la personne vers une alimentation
composée d’aliments faibles en lipides et en sucre et abondante en fruits et légumes, et que
les femmes rapportent être plus souvent à la diète que les hommes, il est possible que les
différences de genre observées dans les habitudes alimentaires s’expliquent en partie par
l’histoire de diètes (Liebman et al., 2001; Wardle et al., 2000, 2004). Dans le même sens,
certains auteurs suggèrent que les femmes affichent un désir plus important de consommer
des aliments peu caloriques (Fagerli & Wandel, 1999). Par ailleurs, selon une étude menée
aux Pays-Bas, les femmes semblent également plus susceptibles que les hommes de
ressentir un sentiment de culpabilité envers la nourriture, de consommer des aliments afin
de se réconforter en présence de stress ou d’ennui et d’avoir certaines pensées obsessives à
l’égard de leur alimentation (Beardsworth, 2002). En résumé, des distinctions sont
observées entre les hommes et les femmes dans leur relation envers la nourriture.
25
Plusieurs outils ont été proposés afin de mesurer différents aspects reliés aux
comportements alimentaires. Le Three-Factor Eating Questionnaire permet d’évaluer
certaines dimensions du comportement alimentaire, plus spécifiquement la restriction
cognitive (qui se caractérise par l’intention de contrôler la quantité ou la qualité de ses
apports alimentaires afin de contrôler son poids), la désinhibition (qui se définit par une
surconsommation d’aliments en réponse à une variété de stimuli associés à un sentiment de
perte de contrôle sur la prise alimentaire) et la susceptibilité à la faim (qui réfère à la
consommation d’aliments en réponse à des sensations et des perceptions de faim interne et
externe), et fut utilisé dans un très grand nombre d’études (Stunkard & Messick, 1985). Des
différences relatives au genre ont été documentées à l’égard de ces comportements
alimentaires. De façon générale, les femmes présentent un niveau de restriction cognitive
plus élevé que les hommes et sont plus susceptibles de restreindre volontairement leurs
apports alimentaires dans le but de contrôler leur poids corporel ou de favoriser la perte de
poids (Carmody et al., 1995; Neumark-Sztainer et al., 1999; Provencher et al., 2003). Bien
que la littérature ne soit pas unanime à ce sujet, certaines études rapportent une association
négative entre la restriction cognitive et l’apport énergétique (de Castro, 1995; Lindroos et
al., 1997). En ce qui a trait à la désinhibition alimentaire, les hommes présentent en général
des niveaux moins élevés que les femmes (Carmody et al., 1995; Neumark-Sztainer et al.,
1999; Provencher et al., 2003). Cependant, selon une étude de Drapeau et al., les hommes
seraient plus susceptibles à la désinhibition situationnelle, c’est-à-dire associée à des
facteurs contextuels tels que la présence de nourriture, et moins à la désinhibition
émotionnelle, c’est-à-dire associée à des émotions positives ou négatives, par rapport aux
femmes (Drapeau et al., 2003). Chez les hommes comme chez les femmes, la désinhibition
est associée positivement à l’apport énergétique (Lindroos et al., 1997) ainsi qu’à la densité
énergétique (Goulet et al., 2008). En ce qui concerne la susceptibilité à la faim, il semble
que les hommes soient plus influencés par des sensations de faim interne comparativement
aux femmes, ce qui suggère une perception plus efficace des sensations physiologiques de
la faim chez les hommes (Drapeau et al., 2003).
En résumé, les différences entre les hommes et les femmes liées aux attitudes, croyances,
responsabilités, rôles sociaux et comportements à l’égard de l’alimentation et de la santé
26
sont de plus en plus documentées dans la littérature et méritent d’être considérées dans le
contexte de changements alimentaires (Arganini, 2012; Beardsworth, 2002; Wardle et al.,
2004).
1.4.3 Impact de l’alimentation sur la santé : l’influence du sexe
Des différences fondamentales existent entre les hommes et les femmes quant à l’impact de
l’alimentation sur la santé. Plus précisément, le fait qu’un même changement alimentaire
exerce des effets différents sur le profil métabolique des hommes et des femmes relève
davantage de différences sexuelles. Jusqu’à maintenant, une part considérable de ces
différences a été attribuée aux rôles des estrogènes (Brown & Clegg, 2010).
Les différences observées entre les hommes et les femmes quant aux effets de la prise
alimentaire sur la santé seraient en partie attribuables aux rôles des estrogènes liés à la
composition et la distribution du tissu adipeux (Brown & Clegg, 2010; Stevens et al.,
2010). En effet, les femmes présentent un pourcentage de tissu adipeux plus élevé que les
hommes et emmagasinent une proportion plus importante de tissu adipeux au niveau souscutané. À l’inverse, les hommes présentent un pourcentage de tissu adipeux plus faible et
emmagasinent de façon préférentielle le tissu adipeux au niveau abdominal. Dans la
littérature, il est bien établi que l’accumulation de tissu adipeux au niveau abdominal
contribue à augmenter le risque de MCV, notamment par le développement de
dyslipidémies et de la résistance à l’insuline (Bjorntorp, 1996; Wajchenberg, 2000). Les
estrogènes pourraient expliquer en partie ces différences dans la composition corporelle,
possiblement par un taux d’oxydation des acides gras plus faible en état postprandial chez
les femmes que chez les hommes (Wu & O'Sullivan, 2011). En d’autres mots, une
conversion de l’énergie sous forme de tissu adipeux serait favorisée chez les femmes par
l’effet des estrogènes. D’autre part, ces hormones semblent aussi réguler la distribution du
tissu adipeux. En effet, le tissu adipeux abdominal varie inversement selon les niveaux
d’estrogènes (Bouchard et al., 1993) et l’accumulation de tissu adipeux abdominal se
produit chez les femmes lorsque les niveaux d’estrogènes deviennent suffisamment faibles
(Shi et al., 2009). Enfin, plusieurs travaux indiquent que les estrogènes seraient également
27
impliquées dans la régulation de la prise alimentaire et des sensations d’appétit (Shi et al.,
2009; Brown & Clegg, 2010). Par exemple, ces hormones pourraient influencer l’action de
l’insuline liée à l’équilibre énergétique via une influence sur la prise alimentaire et
l’entreposage du tissu adipeux (Shi et al., 2009; Brown & Clegg, 2010). De façon
sommaire, ces travaux indiquent que l’impact d’une perte ou d’un gain de poids sur
l’accumulation ou la mobilisation des graisses n’est pas le même chez les hommes et les
femmes en raison de leur profil hormonal, et que ces différences dans la distribution du
tissu adipeux peut avoir des effets sur le profil métabolique.
Des différences sexuelles en réponse à des interventions nutritionnelles menées dans un
contexte isocalorique, c’est-à-dire un contexte où le poids demeure stable, ont également
été observées dans la littérature. En effet, les travaux de Knopp et al. ont montré qu’un
changement dans les apports en lipides et en glucides avait un impact plus important sur les
concentrations de C-LDL et sur le ratio C-total sur C-HDL chez les hommes que chez les
femmes. Au contraire, ce même changement alimentaire avait un impact plus important sur
les concentrations de C-HDL et de triglycérides chez les femmes que chez les hommes
(Knopp et al., 2005). Ces résultats suggèrent que les changements alimentaires n’ont pas
nécessairement les mêmes effets sur les facteurs de risque cardiovasculaire chez les
hommes et les femmes, et que ces différences pourraient s’expliquer par les hormones
sexuelles (Knopp et al., 2005).
En résumé, dans un contexte qui reproduit les conditions de vie réelle, par exemple une
intervention nutritionnelle visant à améliorer les habitudes alimentaires et la santé, les
différences rapportées entre les hommes et les femmes peuvent ainsi s’expliquer à la fois
par des différences relatives au genre et des différences sexuelles, et le fait de considérer
ces deux concepts favorise une compréhension plus exacte des différences entre les
hommes et les femmes dans la réponse à une intervention nutritionnelle.
28
1.5 Différences entre les hommes et les femmes en réponse à une intervention
nutritionnelle visant la prévention de maladies cardiovasculaires
Peu d’études ont directement comparé les hommes et les femmes dans leur réponse à une
intervention nutritionnelle. Néanmoins, certaines études suggèrent que les changements
observés en ce qui a trait au profil métabolique ne seraient pas les mêmes chez les hommes
et les femmes en réponse à une intervention nutritionnelle donnée (Knopp et al., 2005; Li et
al., 2003; Weggemans et al., 1999). Plus précisément, des différences entre les hommes et
les femmes ont été rapportées en réponse à des interventions visant la modification de la
composition en macronutriments d’une diète dans un contexte d’intervention contrôlée,
c’est-à-dire où une partie ou la totalité des aliments et boissons à consommer est fournie
aux individus.
Comme la diminution des lipides alimentaires a longtemps été la principale cible en
prévention et dans le traitement des MCV, plusieurs études ont comparé les hommes et les
femmes dans un contexte d’intervention visant la diminution des apports en lipides totaux
et en acides gras saturés. Certaines études ont démontré que les hommes répondaient mieux
à une intervention nutritionnelle visant la diminution de leur apport en acides gras saturés,
par une diminution des concentrations de C-LDL plus importante que chez les femmes
(Knopp et al., 2005; Li et al., 2003; Weggemans et al., 1999). Une étude de Li et al.
effectuée auprès d’hommes et de femmes présentant un risque modéré de dyslipidémies
rapporte une diminution plus marquée des concentrations de C-LDL chez les hommes
comparativement aux femmes en réponse à une diète faible en lipides totaux et en acides
gras saturés dans un contexte isocalorique (Li et al., 2003). Des résultats semblables ont été
rapportés par Weggemans et al. chez des hommes et des femmes en santé, avec des
diminutions plus importantes des concentrations de C-total et de C-LDL chez les hommes
que chez les femmes en réponse à une diète faible en acides gras saturés (Weggemans et
al., 1999). Comme ces interventions ont été effectuées dans un contexte contrôlé, les
différences rapportées entre les hommes et les femmes dans les changements métaboliques
s’expliqueraient davantage par des différences sexuelles, et possiblement en partie par les
hormones sexuelles (Knopp et al., 2005). Il est toutefois à noter que dans la littérature,
29
certaines études ne rapportent aucune différence entre les hommes et les femmes dans la
réponse à une diète donnée (Lapointe et al., 2006). Des différences liées au type et à la
quantité de lipides ciblés de même que la contribution d’autres facteurs nutritionnels tels
que l’apport en glucides pourraient expliquer les divergences observées entre les études.
1.6 Différences entre les hommes et les femmes dans le contexte de
l’alimentation méditerranéenne
1.6.1 Différences entre les hommes et les femmes dans l’adhésion à l’alimentation
méditerranéenne
L’impact de l’alimentation méditerranéenne sur le risque de MCV a rarement été évalué
chez les hommes et les femmes distinctement. D’un point de vue épidémiologique,
quelques études réalisées dans des populations méditerranéennes indiquent un effet
bénéfique plus important de l’alimentation méditerranéenne chez les femmes que chez les
hommes. Une étude de Chrysohoou et al. menée auprès d’hommes et de femmes grecs
visait à comparer les hommes et les femmes quant à l’impact des facteurs de risque
cardiovasculaire sur le risque de développer une MCV au sein d’une population
méditerranéenne (Chrysohoou et al., 2003). Leurs résultats indiquent que les femmes
adhèrent davantage à l’alimentation méditerranéenne traditionnelle comparativement aux
hommes, ce qui expliquerait l’effet protecteur plus important de cette alimentation sur le
risque de MCV chez les femmes que chez les hommes. Une autre étude ayant évalué l’effet
de l’adhésion à l’alimentation méditerranéenne sur la présence de facteurs de risque
impliqués dans le développement de MCV rapporte des résultats semblables, avec un effet
protecteur plus marqué de l’alimentation méditerranéenne sur la santé cardiovasculaire des
femmes que des hommes (Panagiotakos et al., 2007).
30
1.6.2 Différences entre les hommes et les femmes dans la réponse à une intervention
nutritionnelle basée sur l’alimentation méditerranéenne
Dans le contexte d’une intervention contrôlée menée dans des conditions isocaloriques, une
récente étude québécoise s’est intéressée aux différences entre les hommes et les femmes
quant à l’impact de l’alimentation méditerranéenne sur les facteurs de risque
cardiovasculaire (Bédard et al., 2014). Cette étude a démontré une différence entre la
réponse des hommes et celle des femmes en ce qui a trait aux changements dans
l’homéostasie de l’insuline en réponse à l’adhésion à l’alimentation méditerranéenne, avec
une amélioration observée chez les hommes seulement. Ces résultats démontrent que
l’adoption de l’alimentation méditerranéenne engendre des changements métaboliques
attribuables à des différences sexuelles, mais n’excluent pas la possibilité de différences
relatives au genre, comme par exemple des différences liées au niveau d’adhésion aux
recommandations alimentaires.
À ce propos, certaines études ont évalué la réponse des hommes et des femmes à un
programme d’éducation en nutrition visant l’adoption de l’alimentation méditerranéenne.
En effet, les résultats d’une intervention effectuée dans une population italienne à risque de
MCV indiquent que l’adhésion à l’alimentation méditerranéenne mène à des effets
bénéfiques similaires sur certains facteurs de risque cardiovasculaire non traditionnels, plus
particulièrement sur la dysfonction endothéliale et sur les marqueurs de l’inflammation,
chez les hommes et les femmes (Esposito et al., 2004). Cependant, puisque les auteurs ne
rapportent pas le niveau d’adhésion à l’alimentation méditerranéenne, il est impossible de
déterminer si l’amélioration des facteurs de risque est associée à une adhésion aux
recommandations alimentaires semblable chez les hommes et les femmes.
Récemment, le succès du programme d’éducation en nutrition développé dans le cadre de
l’intervention PREDIMED a été rapporté selon le genre (Zazpe et al., 2010). Plus
précisément, l’intervention était d’une durée de 12 mois et basée sur une approche
motivationnelle, et incluait 1) une rencontre individuelle tous les trois mois lors de laquelle
les personnes recevaient des recommandations individualisées favorables à l’adhésion à
31
l’alimentation méditerranéenne; 2) une rencontre de groupe tous les trois mois; 3) de la
documentation fournissant une description des aliments méditerranéens traditionnels, une
liste d’achats variant au fil des saisons, des plans alimentaires, des recommandations en lien
avec la fréquence de consommation à atteindre et des recettes; 5) une quantité constante
d’huile d’olive vierge (équivalente à 1L / semaine) ou de noix mélangées (équivalente à 30
g/jour) (Zazpe et al., 2008). Il est à noter qu’aucune restriction calorique n’était exigée de la
part des participants dans le cadre de cette étude. Les auteurs évaluaient le succès de
l’intervention par l’atteinte d’un minimum de quatre des cinq changements visant à
améliorer l’adhésion à l’alimentation méditerranéenne. Plus spécifiquement, les
changements visés se traduisaient par une augmentation de la consommation de fruits, de
légumes et du ratio acides gras monoinsaturés sur acides gras saturés, et une diminution de
la consommation de viandes et de sucreries. Les résultats de cette étude ont démontré un
succès plus élevé en terme d’adhésion à l’alimentation méditerranéenne chez les hommes
que chez les femmes (Zazpe et al., 2008). Les travaux de ces auteurs ne permettent
toutefois pas de mettre directement en relation le succès de l’intervention selon le niveau
d’adhésion à l’alimentation méditerranéenne et l’amélioration des facteurs de risque
cardiovasculaire après l’intervention de 12 mois selon le genre. En effet, seuls les
changements métaboliques observés après trois mois d’intervention ont été évalués
distinctement chez les hommes et les femmes (Estruch et al., 2006). Ces résultats indiquent
que les hommes et les femmes améliorent de façon semblable leurs facteurs de risque
cardiovasculaire au cours des trois premiers mois d’intervention (Estruch et al., 2006).
Les différences entre les hommes et les femmes en réponse à un programme d’éducation en
nutrition ont également été rapportées dans une population non méditerranéenne. En effet,
une étude menée aux Pays-Bas a évalué l’impact d’un programme d’éducation visant
l’adoption de l’alimentation méditerranéenne auprès d’hommes et de femmes présentant
une hypercholestérolémie (Bemelmans et al., 2000). L’intervention était d’une durée de 12
mois et comportait trois rencontres de groupe. Ces rencontres visaient principalement à
transmettre des connaissances reliées à l’alimentation méditerranéenne et à améliorer les
habiletés relatives à l’achat et la préparation des aliments (Siero et al., 2000). Des
recommandations alimentaires spécifiques portant sur le nombre de portions à consommer
32
quotidiennement étaient également transmises aux participants (Siero et al., 2000). Les
auteurs rapportent que les femmes ont augmenté de façon significative leur apport en fibres
alimentaires, leur consommation de fruits et de volaille, et diminué leur consommation de
viandes rouges, alors que de tels changements n’ont pas été observés chez les hommes
(Bemelmans et al., 2000). Les résultats indiquent aussi une diminution des concentrations
de C-total chez les femmes et non chez les hommes en réponse à l’intervention, suggérant
ainsi un meilleur succès de l’intervention chez les femmes (Bemelmans et al., 2000).
En définitive, parmi les rares études ayant comparé l’impact de l’alimentation
méditerranéenne sur le risque de MCV selon le genre, les données suggèrent pour la plupart
que les hommes et les femmes répondent différemment à une intervention nutritionnelle
basée sur l’alimentation méditerranéenne en ce qui concerne les changements
métaboliques, et que ces différences peuvent s’expliquer en partie par le niveau d’adhésion
à l’intervention.
1.7 Théories de changements de comportements liés à la santé
Les théories de changements de comportements visent à comprendre les mécanismes sousjacents et à identifier les cibles d’intervention favorables à un changement de
comportement, et permettent ainsi de développer des interventions pouvant conduire à un
changement planifié des comportements. Un survol de trois théories couramment citées
dans le domaine du changement de comportement en santé, soit 1) la théorie sociale
cognitive, 2) le modèle transthéorique et 3) la théorie de l’autodétermination, est présenté
dans cette section.
1.7.1 Théorie sociale cognitive
La théorie sociale cognitive (TSC) a été développée par Bandura en 1986 et se décrit à la
fois comme une théorie de prédiction et du changement de comportement (Bandura, 1986).
En effet, elle permet non seulement d’expliquer le comportement à partir de divers
33
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d’adopter le comportement puisqu’elle a le sentiment d’avoir les compétences et présente
un état émotionnel moins négatif. Une des principales forces de la TSC s’explique par le
fait que cette théorie permet de prédire un changement de comportement, en plus de fournir
des stratégies pour amener un individu à changer son comportement (Godin, 2012).
Cependant, on rapporte que ce modèle s’avère complexe à utiliser lorsque considéré dans
son intégralité (Godin, 2012).
1.7.2 Modèle transthéorique
Prochaska et DiClemente sont les auteurs du modèle transthéorique (MTT) dont l’origine
remonte dans les années 1980 (Prochaska & DiClemente, 1983). Le MTT aborde le
changement de comportement comme un processus dynamique qui évolue à travers
différents stades. Essentiellement, le modèle permet d’évaluer six stades du changement,
deux processus cognitifs (attitude et efficacité personnelle) ainsi que divers processus de
changement (Godin, 2012). Plus spécifiquement, les stades de changement incluent la
précontemplation (pré-réflexion), la contemplation (réflexion), la préparation, l’action, le
maintien et la conclusion (terminaison) (Figure 3).
Figure 3. Schématisation du modèle transthéorique. Adaptée de Prochaska et al., 1994, et
tirée du livre Les comportements dans le domaine de la santé (Godin, 2012).
35
Selon le MTT, le cheminement d’une personne à travers les stades du changement n’est pas
nécessairement linéaire et le changement entre deux stades peut s’effectuer de façon
progressive ou régressive. De plus, l’atteinte d’un stade n’est pas définitive, c’est-à-dire
qu’une personne peut par exemple atteindre le stade d’action et retourner en contemplation
par la suite. Cette théorie suggère des stratégies expérientielles (visant la prise de
conscience) et des stratégies comportementales (impliquées dans le processus décisionnel
d’action) ayant pour objectif de favoriser le passage d’un stade à l’autre. Le MTT propose
également deux processus cognitifs permettant de prédire l’adoption d’un comportement, le
premier étant la balance décisionnelle où sont évalués les avantages et les désavantages
perçus à l’adoption du comportement, et le deuxième est celui de l’efficacité personnelle.
Ce modèle soutient que les personnes de stades différents se distingueraient par leurs
attitudes (avantages et désavantages perçus) et leur sentiment d’efficacité personnelle, et
présenteraient des cognitions plus favorables en progressant à travers les stades de
changement. Le MTT permet d’identifier les cognitions susceptibles d’être présentes chez
les individus selon le stade où ils se trouvent et permet alors de préciser le message à leur
transmettre, ce qui constitue l’une des principales forces de ce modèle (Godin, 2012).
Toutefois, ce dernier s’avère critiqué en raison du fait que des périodes de temps arbitraires
sont suggérées afin de définir les différents stades de changement et que le délai nécessaire
pour modifier un comportement est fixe peu importe le comportement et la population
ciblés.
En résumé, on constate que la TSC et le MTT sont des théories qui permettent de prédire
un changement de comportement. Or, dans le but de développer une intervention
nutritionnelle visant des changements alimentaires durables, il s’avère pertinent de recourir
à une théorie qui prédit également le maintien du comportement. Une particularité qui
distingue la théorie de l’autodétermination (TAD) des autres théories présentées dans cette
section relève du fait qu’elle permet à la fois de prédire le changement et le maintien d’un
comportement (Deci & Ryan, 1985; Ryan & Deci, 2000). D’autre part, la motivation est
reconnue comme un facteur déterminant dans le changement des habitudes et
comportements alimentaires et cette théorie repose essentiellement sur la qualité de la
motivation humaine (Deci & Ryan, 1985; Ryan & Deci, 2000).
36
1.7.3 Théorie de l’autodétermination
La TAD est une théorie proposée par les auteurs Deci et Ryan et s’intéresse à la qualité de
la motivation impliquée dans la régulation d’un comportement ainsi qu’aux conséquences
sur l’apprentissage, la performance, l’expérience personnelle et le bien-être qui s’y
rattachent (Deci & Ryan, 1985; Ryan & Deci, 2000).
Cette théorie postule qu’un comportement peut être régulé par différentes formes de
motivation qui se distinguent par leur niveau d’autodétermination (Deci & Ryan, 1985;
Ryan & Deci, 2000). Ces formes de motivation sont regroupées en trois catégories, soit la
motivation intrinsèque, la motivation extrinsèque (incluant la régulation externe,
introjectée, identifiée et intégrée) et l’amotivation. Plus précisément, la motivation
intrinsèque reflète le degré le plus élevé d’autodétermination et se définit par le fait de
s’investir dans une activité pour la satisfaction et le plaisir émanant de l’activité elle-même.
Par exemple, dans le contexte alimentaire, une personne qui prend plaisir à cuisiner des
repas équilibrés fait preuve d’une motivation intrinsèque. La régulation intégrée constitue la
forme la plus autodéterminée de la motivation extrinsèque et représente l’assimilation de la
régulation aux valeurs personnelles, c’est-à-dire que la régulation est en parfaite
congruence avec les besoins et autres valeurs de la personne. Un individu qui choisit de
manger sainement parce que cela fait partie intégrante de son style de vie démontre une
régulation intégrée. La régulation identifiée reflète la participation à une activité en raison
d’une conséquence personnellement significative et importante de la mise en pratique de
l’activité, malgré le fait que la personne peut ne pas apprécier l’activité en soi. Par exemple,
si une personne considère que de manger sainement est une façon de s’assurer des bienfaits
à long terme au plan de la santé, celle-ci fait preuve de régulation identifiée. La régulation
introjectée survient quand un comportement est guidé par des pressions internes, afin
d’éviter les émotions négatives telles que l’anxiété et le sentiment de culpabilité. On peut
reconnaître la régulation introjectée si par exemple une personne se soucie de son
alimentation parce qu’elle ne veut pas avoir honte de son apparence. La régulation externe
constitue la forme de régulation la moins autodéterminée et qui s’observe lorsqu’un
individu effectue une activité dans le but d’obtenir une récompense ou afin d’éviter les
37
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En plus de s’intéresser aux différentes formes de motivation, la TAD vise à expliquer les
processus par lesquels les comportements non motivés de façon intrinsèque peuvent
devenir véritablement autodéterminés de même que les façons d’influencer ces processus
(Deci & Ryan, 1985; Ryan & Deci, 2000). Selon la TAD, une personne n’a pas à
progresser par tous les niveaux d’autodétermination dans son évolution face au
changement. Il s’agit plutôt d’un progrès qui tient compte de l’expérience antérieure de la
personne et de facteurs environnementaux plus ou moins favorables (Ryan, 1995). Cette
théorie soutient qu’une personne peut intérioriser l’importance d’un changement, faisant en
sorte qu’un comportement initialement régulé par des motifs externes (régulation externe)
peut évoluer vers une régulation plus autodéterminée, à condition que les besoins
psychologiques fondamentaux relatifs à l’autonomie, la compétence et au sentiment
d’attachement soient satisfaits (Ryan & Deci, 2000). L’autonomie réfère à la perception
d’effectuer une action par choix personnel et d’avoir le sentiment d’être l’initiateur de ses
actions; la compétence réfère à la perception de se sentir en contrôle de son environnement
et capable de prédire les conséquences de ses actions; le sentiment d’attachement réfère au
besoin d’entrer en relation avec les autres et de ne pas se sentir en rupture avec les valeurs
associées à son milieu social de référence (Ryan & Deci, 2000). En terme de conséquences
reliées à la motivation, les comportements motivés de façon autonome sont plus
susceptibles de mener à des effets positifs et de se maintenir dans le temps alors que les
comportements motivés de façon contrôlée sont plutôt associés à des effets négatifs et
tendront à être maintenus aussi longtemps qu’il y aura présence d’incitatifs externes (p.ex.,
récompenses, pression) (Ryan & Deci, 2000; Silva et al., 2008; Vallerand, 1997). Des
travaux menés dans divers contextes de vie soutiennent cette proposition (Vallerand, 1997).
En effet, les formes de régulation autodéterminées ont été associées à des effets positifs sur
l’apprentissage, l’intérêt, la persévérance, les efforts, la performance, l’estime de soi, la
santé et la satisfaction à l’égard de la vie, alors que les formes de régulation non
autodéterminées ont plutôt été associées négativement à ces effets (Vallerand, 1997).
Dans ce modèle théorique, on reconnaît également que le contexte social influence de
manière importante la satisfaction des besoins psychologiques, et par le fait même la
motivation autodéterminée. À ce sujet, la théorie propose que le soutien à l’autonomie
39
s’avère favorable à la régulation d’un comportement de manière plus autodéterminée (Deci
et al., 1994). Dans le cadre d’une intervention visant un changement de comportement, un
climat d’intervention favorisant le soutien à l’autonomie s’explique par le fait de considérer
le point de vue de la personne, de soutenir ses initiatives, d’offrir plusieurs options, de
respecter ses choix, de fournir de l’information pertinente, tout en minimisant la pression et
le contrôle exercés (Deci & Ryan, 2012).
Bien que la motivation autodéterminée soit abordée dans le contexte de l’alimentation dans
le cadre de cette thèse, il importe de mentionner l’existence du modèle hiérarchique de la
motivation autodéterminée proposé par Vallerand et al. (Vallerand, 1997; Vallerand &
Blanchard, 1998; Vallerand & Ratelle, 2002). Selon ce modèle, les différentes formes de
motivation (intrinsèque, extrinsèque et l’amotivation) coexistent à trois niveaux, soit
situationnel, contextuel et global, et des interactions entre les différents niveaux
motivationnels sont possibles (Vallerand, 1997). On soutient également que la motivation
exprimée dans une situation ou dans un contexte donné est plus sujette à changer dans le
temps que la motivation globale, qui réfère à l’orientation motivationnelle et qui est
assimilable à la personnalité de l’individu. De plus, la motivation évaluée sous un angle
contextuel s’avèrerait plus utile afin d’expliquer le changement d’un comportement donné
dans un contexte spécifique.
1.7.3.1 Les comportements de santé basés sur la théorie de l’autodétermination
Plusieurs études effectuées dans divers domaines de la santé appuient les fondements de la
TAD. De façon générale, ces études démontrent qu’un niveau de motivation
autodéterminée élevé et la présence de motivation intrinsèque constituent des prédicteurs
du succès relié à l’autorégulation de la pratique d’activité physique (Fortier et al., 2007a),
des comportements alimentaires (Mata et al., 2009; Pelletier & Dion, 2007; Pelletier et al.,
2004), de la régulation du poids corporel (Teixeira et al., 2006), de l’observance à la
médication à long terme (Williams et al., 1998), de l’amélioration du contrôle de la
glycémie et du respect des recommandations alimentaires chez les patients diabétiques
(Williams et al., 1998) et du maintien de la cessation tabagique (Williams et al., 2002b).
40
Des données soutiennent l’impact positif de la motivation autodéterminée sur le maintien
d’un changement de comportement de santé à long terme (Fortier et al., 2007a; Teixeira et
al., 2006; Williams et al., 1996). À ce propos, certains auteurs indiquent clairement que le
fait de se sentir autonome de ses propres actions, c’est-à-dire d’avoir un sentiment d’être
libre de ses actions, s’avère un prédicteur crucial pour le maintien du changement de
comportement (Williams et al., 2002b).
La littérature appuie également l’importance d’un climat d’intervention de qualité dans les
changements de comportement de santé. Plusieurs études démontrent que la perception du
soutien à l’autonomie de la part d’un intervenant prédit la satisfaction des besoins
psychologiques fondamentaux (autonomie, compétence et sentiment d’attachement) et
favorise la régulation d’un comportement de façon autodéterminée (Deci et al., 1994;
Edmunds et al., 2008; Ng et al., 2012; Silva et al., 2010; Williams et al., 2002a). De plus,
la satisfaction de ces besoins et la motivation autodéterminée auraient des effets favorables
sur le bien-être, notamment une meilleure santé mentale et des comportements de santé plus
sains (Ng et al., 2012).
Enfin, la promotion de la motivation autonome envers un comportement de santé donné
pourrait avoir des effets favorables dans la régulation d’autres comportements de santé, et
ainsi avoir des effets synergiques sur la santé des individus (Dunn et al., 2006; Jakicic et
al., 2002). Les résultats d’une étude de Mata et al. supportent ces propos et indiquent que la
motivation autonome envers la pratique d’activité physique contribue en partie à
l’amélioration de la régulation du comportement alimentaire (Mata et al., 2009).
1.7.3.2 La motivation autodéterminée à l’égard de l’alimentation
La TAD permet également de mieux comprendre les processus de régulation du
comportement alimentaire. À ce jour, peu d’études ont toutefois considéré la motivation
autodéterminée spécifique au contexte de l’alimentation. Des données indiquent d’une part
que les personnes qui présentent une motivation autodéterminée dans la vie en général
41
tendent davantage à réguler leurs comportements alimentaires de façon autodéterminée, et
d’autre part, qu’une régulation autodéterminée à l’égard de l’alimentation est associée à des
habitudes et comportements alimentaires sains (Fuemmeler et al., 2006; Pelletier & Dion,
2007; Pelletier et al., 2004).
Selon une étude de Pelletier et al. menée auprès d’étudiantes universitaires, les femmes qui
présentent une régulation autodéterminée à l’égard de leur alimentation sont plus
susceptibles d’avoir des apports alimentaires concordants avec les recommandations du
Guide alimentaire canadien, c’est-à-dire de consommer des légumes, des fruits et des
produits céréaliers, d’avoir des apports modérés en lipides totaux, en acides gras saturés et
en cholestérol, et de limiter leur consommation de croustilles, de chocolat, d’aliments frits
et de sucre raffiné, et ce comparativement aux femmes présentant une régulation non
autodéterminée (Pelletier et al., 2004). Par ailleurs, les auteurs rapportent que les femmes
ayant une régulation autonome à l’égard de leur alimentation se soucient principalement de
la qualité des aliments consommés alors que les femmes affichant plutôt une régulation
contrôlée se préoccuperont davantage de la quantité de nourriture consommée. Leurs
résultats montrent également que les femmes qui présentent une motivation autonome ont
des comportements alimentaires plus sains et un bien-être psychologique accru (Pelletier et
al., 2004). Au contraire, celles qui présentent une régulation contrôlée semblent avoir une
alimentation moins saine, des comportements alimentaires plus dysfonctionnels
(symptômes boulimiques) et sont plus susceptibles de présenter une détresse
psychologique.
Ces mêmes auteurs ont effectué une étude longitudinale visant à tester l’impact de la
motivation autodéterminée sur l’amélioration des habitudes alimentaires auprès de
personnes à risque de MCV (Pelletier et al., 2004). Leurs résultats indiquent que les
personnes qui présentaient une motivation autodéterminée à l’égard de l’alimentation
diminuaient davantage le pourcentage de calories consommées provenant des lipides totaux
et des gras saturés, menant ainsi à des effets favorables sur la santé cardiovasculaire, plus
spécifiquement à une diminution du poids corporel et une amélioration du profil lipidique,
en réponse à une intervention menée sur une période de 26 semaines. Cette étude démontre
42
que les personnes ayant une régulation autodéterminée à l’égard de l’alimentation font
preuve d’efforts plus soutenus afin d’obtenir des effets favorables sur leur santé à long
terme.
Une étude épidémiologique de Leong et al. réalisée auprès de femmes de la NouvelleZélande a testé l’effet médiateur potentiel des habitudes et comportements alimentaires
dans la relation entre de la motivation autodéterminée et l’IMC (Leong et al., 2012). Leurs
résultats ont d’abord permis de démontrer qu’une motivation autonome était associée
positivement à des habitudes et comportements alimentaires sains (p.ex., consommation
plus élevée de légumes et de fruits) et était associée négativement aux comportements
alimentaires moins sains (p.ex., consommation plus faible de chocolat, biscuits, gâteaux,
hamburgers et croustilles et risque plus faible d’hyperphagie boulimique). À l’inverse, la
motivation contrôlée était associée négativement aux comportements alimentaires sains et
était associée positivement à certains comportements alimentaires moins sains. Par ailleurs,
la motivation autonome était associée à un IMC plus faible alors que la motivation
contrôlée était associée à un IMC plus élevé. Les auteurs de cette étude ont finalement
démontré que les habitudes et comportements alimentaires des femmes exerçaient un effet
médiateur partiel dans la relation entre la motivation autonome et l’IMC de même que dans
la relation entre la motivation contrôlée et l’IMC.
De façon sommaire, ces études démontrent qu’un comportement régulé via la motivation
autodéterminée spécifique à l’alimentation peut avoir un impact positif sur la santé, plus
particulièrement en favorisant une alimentation saine (Verstuyf et al., 2012) et le maintien
de ces habitudes alimentaires à long terme (Pelletier et al., 2004).
1.7.3.3 Différences entre les hommes et les femmes quant à la motivation autodéterminée
Certaines différences ont été rapportées entre les hommes et les femmes en lien avec la
régulation de la motivation autodéterminée. Des études menées dans divers domaines tels
que la santé, les relations interpersonnelles et le milieu académique démontrent en général
43
un niveau de motivation autodéterminée plus élevé chez les femmes que chez les hommes
(Vallerand & Bissonnette, 1992; Vallerand et al., 1997; Vallerand & O'Connor, 1989).
Dans le domaine des comportements de santé, une récente étude ayant évalué la motivation
autodéterminée d’hommes et de femmes à l’égard d’un poids santé, c’est-à-dire leurs
raisons de viser l’atteinte d’un poids santé, rapporte des niveaux de motivation
autodéterminée et de régulation introjectée plus élevés chez les femmes que chez les
hommes (Hartmann et al., 2015). Les individus amotivés quant au fait de fournir des efforts
pour tendre vers ou maintenir un poids santé étaient exclus de l’étude et principalement
représentés par des hommes (67,3%). Les résultats de cette étude ont montré que la
régulation autodéterminée prédisait l’amélioration de la qualité de l’alimentation un an plus
tard à la fois chez les hommes (par une consommation plus faible de viande) et chez les
femmes (par une consommation plus élevée de légumes).
En ce qui a trait à la motivation spécifique au contexte alimentaire, les résultats d’une
récente étude menée auprès de jeunes adultes suggèrent que la régulation du comportement
alimentaire via une motivation autonome favorise un profil anthropométrique sain chez les
femmes, mais non chez les hommes (Gropper et al., 2014). Plus spécifiquement, les
résultats démontrent que les femmes présentant une motivation autodéterminée à l’égard de
leur alimentation ont un IMC et un pourcentage de tissu adipeux plus faibles. Chez les
hommes, seulement certaines formes de régulation contrôlée étaient associées au profil
anthropométrique. Plus spécifiquement, la régulation introjectée et l’amotivation étaient
respectivement associées à un IMC et à un pourcentage de tissu adipeux plus élevés chez
les hommes. Bien que ces résultats suggèrent un patron d’associations distinct entre les
variables motivationnelles spécifiques au contexte alimentaire et le profil anthropométrique
selon le genre, ces différences demeurent peu discutées par les auteurs.
En définitive, on constate qu’il y a actuellement peu de littérature portant sur la motivation
autodéterminée spécifique au contexte de l’alimentation, et qu’une seule étude semble avoir
considéré les hommes et les femmes distinctement. Par ailleurs, aucune étude n’a mis en
44
relation la motivation autodéterminée à l’égard de l’alimentation et la qualité de
l’alimentation selon le genre.
1.8 Approche de l’entretien motivationnel
L’entretien motivationnel constitue une approche permettant de mettre en application la
théorie de l’autodétermination, par exemple dans le cadre d’une intervention nutritionnelle
visant à changer les comportements alimentaires.
1.8.1 Définition et principes
L’entretien motivationnel constitue une approche qui a été développée dans les années 1980
et qui se définit comme une méthode centrée sur le client, directive, et visant à potentialiser
la motivation intrinsèque envers un changement en utilisant l’exploration et la résolution de
l’ambivalence (Miller & Rollnick, 2002). En d’autres mots, cette approche vise à soutenir
le client dans sa démarche afin qu’il exprime son ambivalence et parvienne à résoudre les
conflits existant entre la volonté de conserver un statut quo (ses comportements actuels) et
celle de changer (ses comportements souhaités), en explorant ses propres valeurs et ses
perceptions (Rollnick & Miller, 1995). De plus, ce style d’intervention se veut directif
puisqu’il a comme objectif de renforcer la motivation intrinsèque et l’engagement du client
envers un changement de comportement, en le soutenant afin qu’il soit en mesure de
prendre lui-même ses décisions face au changement envisagé (Rollnick & Miller, 1995).
Cette approche soutient que l’ambivalence est naturelle devant toute perspective de
changement et peut engendrer un certain niveau de résistance (Miller & Rollnick, 2002). En
ce sens, l’entretien motivationnel vise à diminuer cette résistance en évoquant le discours
au changement, c’est-à-dire en amenant le client à affirmer les avantages qu’il perçoit en
faveur du changement. Les principales composantes sous-jacentes à cette approche sont la
collaboration, l’évocation et l’autonomie (Miller & Rollnick, 2002). La collaboration réfère
à l’interaction entre l’intervenant et le client favorable au développement d’un partenariat
45
qui reconnaît l’expertise et les points de vue du client. L’intervenant crée une atmosphère
propice au changement, plutôt que coercitive (Moyers et al., 2005). L’évocation s’appuie
sur l’idée que le client possède en lui les ressources et la motivation nécessaires à la
résolution de l’ambivalence face au changement. La motivation intrinsèque est renforcée en
faisant appel aux perceptions, aux objectifs et aux valeurs personnelles du client plutôt
qu’en formulant des conseils rigides susceptibles d’augmenter la résistance face au
changement (Miller & Rollnick, 2002; Rollnick & Miller, 1995). L’autonomie réfère pour
sa part au soutien offert par l’intervenant au client dans son droit et sa capacité d’autodirection à prendre une décision éclairée (Miller & Rollnick, 2002; Rollnick & Miller,
1995). L’approche de l’entretien motivationnel propose quatre principes généraux référant
aux attitudes de l’intervenant au cours d’une rencontre, ceux-ci étant 1) d’exprimer de
l’empathie, 2) de faire ressortir les incohérences entre le comportement actuel et les buts ou
les valeurs du client, 3) de gérer les résistances tout en évitant l’argumentation et 4)
d’encourager le sentiment d’efficacité personnelle (Miller & Rollnick, 2002).
Initialement, les auteurs Miller et Rollnick divisaient cette approche en deux phases (Miller
& Rollnick, 2002). La première phase consiste à résoudre l’ambivalence et à bâtir la
motivation intrinsèque au changement (Miller & Rollnick, 2002). À cette étape, une
attention particulière est accordée à l’importance du changement pour le client et à la
confiance que celui-ci éprouve quant à ses capacités de changer. La seconde phase vise
principalement à renforcer l’engagement au changement ainsi qu’à aider le client à
développer et implanter un plan d’action relatif au changement (Arkowitz et al., 2008).
Diverses stratégies permettent l’application des principes généraux liés à cette approche,
soit 1) de poser des questions ouvertes afin de faire émerger les préoccupations du client, 2)
l’écoute réflective, où l’on renvoie au client une image de ses propos, ce qui permet d’aider
une personne à verbaliser ce qu’elle veut dire et à transmettre ce qu’elle ressent de manière
plus explicite, 3) le résumé, où l’on récapitule de façon succincte les propos que le client a
communiqués, ce qui permet à l’intervenant de renchérir sur les éléments motivationnels,
puis 4) la valorisation, où l’intervenant exprime au client la confiance qu’il a en lui et en sa
capacité de changer (Miller & Rollnick, 2002). Ces stratégies sont présentes au cours des
46
deux phases décrites précédemment, mais dans des proportions différentes selon les
objectifs visés (Miller & Rollnick, 2002).
Récemment, certains aspects de l’approche de l’entretien motivationnel ont été raffinés
(Miller & Rollnick, 2013). Parmi les changements apportés, on constate que l’approche est
désormais présentée en quatre phases motivationnelles, plutôt que deux, qui se superposent
dans le temps. Ces phases sont respectivement l’engagement dans la relation, la
focalisation, l’évocation et la planification. Dans le cadre de cette thèse, il semblait
toutefois plus pertinent de s’attarder aux principes d’origine, sur lesquels reposent la
majorité des travaux présentés dans la littérature actuellement et sur lesquels a été
développé notre projet de recherche. Il est à noter que malgré ces changements, la vision de
l’approche reste essentiellement la même.
1.8.2 Complémentarité entre la théorie de l’autodétermination et l’entretien
motivationnel
Certains auteurs ont invoqué la TAD comme un cadre théorique permettant d’expliquer les
processus et l’efficacité de l’entretien motivationnel (Markland et al., 2005). En effet, la
TAD se définit comme une théorie portant sur la motivation humaine et reconnue comme
une approche descendante (top-down) liée au changement de comportement, c’est-à-dire
que les hypothèses formulées découlent d’une théorie (Vansteenkiste et al., 2012). Plus
spécifiquement, une telle approche permet de comprendre les mécanismes sous-jacents aux
interventions basées sur cette théorie et favorables au succès. Par contre, la principale limite
s’avère de parvenir à traduire les concepts théoriques liés à la motivation autodéterminée en
des méthodes d’intervention clinique. Pour sa part, l’entretien motivationnel constitue
plutôt une approche clinique liée au changement de comportement et regroupant diverses
techniques d’intervention. L’entretien motivationnel est considéré par certains auteurs
comme une approche ascendante (bottom-up), c’est-à-dire qui est en grande partie sans
fondement théorique et plutôt basée sur l’intuition et des observations cliniques dans divers
contextes de vie (Vansteenkiste et al., 2012).
47
Au-delà de cette distinction, des similitudes sont notées entre les concepts de la TAD et
ceux de l’entretien motivationnel (Markland et al., 2005; Vansteenkiste & Sheldon, 2006).
D’abord, les deux modèles se basent sur la même hypothèse, soit celle selon laquelle les
êtres humains sont naturellement orientés vers la croissance, la santé et le bien-être
(Markland et al., 2005). Les deux modèles sont explicitement centrés sur l’individu et
orientés sur le processus impliqué dans le changement de comportement plutôt que sur les
conséquences qui en découlent (Markland et al., 2005). La TAD soutient que l’engagement
personnel profond ainsi qu’un climat d’intervention favorisant la satisfaction des besoins
d’autonomie, de compétence et du sentiment d’attachement s’avèrent des conditions
nécessaires au succès des interventions comportementales en santé, et plus particulièrement
au maintien des changements à long terme (Teixeira et al., 2012). En ce sens,
l’environnement social proposé par l’entretien motivationnel concorde avec la satisfaction
de ces trois besoins, soit par une structure encadrant le changement, le soutien à
l’autonomie et l’implication de l’intervenant (Figure 5). De plus, les deux modèles
possèdent comme concept central la motivation, et visent plus particulièrement à
promouvoir la motivation intrinsèque envers un comportement (Deci & Ryan, 2012;
Resnicow & McMaster, 2012). Enfin, dans un contexte de pratique clinique, la TAD et
l’entretien motivationnel encouragent l’intervenant à démontrer de l’empathie, à poser un
regard inconditionnel et à explorer l’ambivalence du client face au changement, et ce sans
porter de jugement et sans exercer de pression (Markland et al., 2005).
48
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physique, alimentation, observance à la médication) (Martins & McNeil, 2009; Miller &
Rose, 2009) ainsi que de la régulation du poids corporel (Barnes & Ivezaj, 2015). Selon un
récent article de revue, l’entretien motivationnel est de façon générale efficace pour initier
et maintenir un changement de comportement (Rubak et al., 2005). La littérature suggère
qu’une intervention basée sur l’entretien motivationnel est plus susceptible de mener à des
effets favorables en comparaison à une intervention traditionnelle ou à un groupe recevant
uniquement de l’information (Lundahl et al., 2013; Rubak et al., 2005). Par ailleurs, en plus
de constituer un style d’intervention applicable dans plusieurs domaines de la santé,
l’efficacité de l’entretien motivationnel a été validée auprès de divers intervenants et
d’individus présentant des caractéristiques variables en termes d’âge, de sexe et d’origine
ethnique (Lundahl et al., 2013).
L’article de revue de Rubak et al. indique que l’entretien motivationnel peut s’avérer
efficace suite à une rencontre d’une durée de 15 minutes et que plus le nombre de
rencontres augmente, plus l’effet tend à être important (Rubak et al., 2005). Dans le cadre
d’études comprenant deux rencontres motivationnelles d’un minimum de 60 minutes, 81%
ont démontré un effet favorable (Burke et al., 2003; Rubak et al., 2005). Certains travaux
précisent que le nombre de rencontres n’est pas associé aux effets observés, mais que le
temps total alloué à l’entretien motivationnel lors d’une rencontre semble influencer les
résultats, avec des effets favorables plus importants observés lors d’une rencontre
prolongée (Lundahl et al., 2013). De plus, l’impact positif de cette approche semble se
prolonger plus d’un an suivant une intervention (Lundahl et al., 2013).
Les limites actuelles des études s’expliquent par le peu d’information fournie en lien avec
les interventions prodiguées et par le fait que le degré de fidélité de l’approche est rarement
rapporté, rendant ainsi l’interprétation des données plus difficile. Davantage d’études
devront évaluer les aspects plus techniques reliés à l’entretien motivationnel, c’est-à-dire la
durée et le nombre de rencontres optimaux afin de favoriser les changements de
comportement. En dépit de cela, aucune étude ne rapporte d’effets négatifs à l’égard de
cette approche (Rubak et al., 2005).
50
1.8.4 L’efficacité de l’entretien motivationnel pour améliorer les changements
alimentaires
Plusieurs études ont évalué l’impact de l’entretien motivationnel dans le contexte de
changements liés aux habitudes alimentaires et à l’activité physique, ceux-ci étant souvent
combinés ensemble (Martins & McNeil, 2009). Globalement, les résultats indiquent que
cette approche s’avère favorable aux changements reliés à l’alimentation et à l’activité
physique, qu’elle soit utilisée seule ou en complément d’une autre intervention (Martins &
McNeil, 2009). Plus spécifiquement, des évidences démontrent que les personnes ayant
reçu une approche basée sur les principes de l’entretien motivationnel améliorent leur
sentiment d’efficacité personnelle à l’égard de leur alimentation et de l’activité physique
(Bennett et al., 2008; Resnicow et al., 2004), augmentent la pratique d’activité physique
(Bennett et al., 2007; Carels et al., 2007; Harland et al., 1999), diminuent leur apport
énergétique (Befort et al., 2008), et augmentent leur consommation de fruits et légumes
(Ahluwalia et al., 2007; Befort et al., 2008; Elliot et al., 2007; Hardcastle et al., 2008). De
plus, certaines études visant des changements dans les habitudes de vie, dont les habitudes
alimentaires, rapportent une diminution de l’IMC en réponse à une intervention basée sur
l’entretien motivationnel (Hardcastle et al., 2008; Schwartz et al., 2007). Les résultats
rapportés dans un récent article de revue amènent un peu de controverse quant aux effets
potentiels de l’entretien motivationnel dans le contexte de changements alimentaires
(Lundahl et al., 2013). En effet, Lundahl et al. indiquent que cette approche ne semble pas
présenter d’avantages évidents dans le domaine de la saine alimentation (Lundahl et al.,
2013). Les auteurs mentionnent toutefois baser leurs conclusions sur seulement six études,
incluant deux études dans lesquelles l’approche motivationnelle n’était pas utilisée lors de
rencontres en personne, mais plutôt via internet ou le téléphone (Lundahl et al., 2013). Il
semble donc que des études supplémentaires seront nécessaires afin de clarifier les
meilleures stratégies à adopter pour assurer le succès d’interventions en nutrition basées sur
cette approche.
En définitive, en tenant compte de l’ensemble des connaissances actuelles, l’entretien
motivationnel s’avère un style d’intervention prometteur dans le contexte de changements
51
alimentaires, pouvant facilement être intégré à d’autres approches efficaces éprouvées, et
ce, plus particulièrement lorsque l’ambivalence et la motivation semblent constituer des
obstacles au changement (Miller & Rose, 2009).
52
CHAPITRE 2 :
Problématique
53
Les bienfaits de l’alimentation méditerranéenne sur la santé, et plus particulièrement sur la
santé cardiovasculaire, sont clairement démontrés dans la littérature (Sofi et al., 2014).
D’autre part, différents travaux soutiennent la faisabilité d’adopter les principes de
l’alimentation méditerranéenne au sein de populations non méditerranéennes dans le but
d’améliorer la santé (Bemelmans et al., 2000; Logan et al., 2010). Plus spécifiquement au
Québec, des données appuient la faisabilité d’adhérer à l’alimentation méditerranéenne
chez les femmes (Goulet et al., 2003; Goulet et al., 2007), mais aucune étude ne permet
actuellement de dresser le portrait chez les hommes. Enfin, dans le but de développer une
intervention nutritionnelle adaptée aux individus et favorable aux changements alimentaires
à long terme, il semble pertinent d’avoir recours à une approche motivationnelle soutenant
l’autonomie, la compétence et le sentiment d’attachement des individus (Pelletier et al.,
2004; Williams et al., 2002b). Devant ces constats, il s’avérait important de confirmer si les
hommes et les femmes retirent les mêmes bienfaits de l’alimentation méditerranéenne en
réponse à une intervention nutritionnelle dans le contexte québécois. Également, il était
pertinent de déterminer de quelle façon la motivation autodéterminée spécifique à
l’alimentation est associée au niveau d’adhésion à l’alimentation méditerranéenne selon le
genre.
Par conséquent, l’objectif général des travaux de cette thèse était de déterminer les
différences entre les hommes et les femmes dans leur réponse à un programme d’éducation
en nutrition de 12 semaines visant l’adoption d’une alimentation de type méditerranéen et
basé sur la théorie de l’autodétermination, plus spécifiquement en termes de changements
dans les apports alimentaires, variables anthropométriques et métaboliques et de la qualité
de vie.
Afin d’atteindre cet objectif, plusieurs objectifs spécifiques ont été définis et poursuivis
dont les résultats sont présentés dans les articles scientifiques aux chapitres 3 à 7 de cette
thèse.
55
Le premier objectif spécifique des présents travaux visait à caractériser et comparer
les besoins psychologiques fondamentaux et les facteurs de motivation des hommes
et des femmes avant le début de l’intervention visant l’adoption de l’alimentation
méditerranéenne.
Des études ont démontré que les femmes sont plus susceptibles de se mettre en
action afin d’améliorer leurs habitudes alimentaires, rapportent de meilleures
connaissances en nutrition et affirment lire davantage les étiquettes
nutritionnelles comparativement aux hommes (Baker & Wardle, 2003;
Krukowski et al., 2006). Ces observations suggèrent que les femmes sont plus
prédisposées à s’engager dans de saines habitudes alimentaires comparativement
aux hommes, ce qui a amené à émettre l’hypothèse que les femmes démontrent
un niveau de motivation autodéterminée plus élevé avant le début de
l’intervention.
Le deuxième objectif spécifique était de déterminer les différences entre les hommes
et les femmes quant aux changements alimentaires, en réponse au programme
d’éducation en nutrition de 12 semaines visant l’adoption d’une alimentation de type
méditerranéen (court terme), ainsi qu’à six mois suivant la fin de l’intervention
nutritionnelle (long terme).
En supposant que les femmes allaient avoir une alimentation de meilleure qualité
que les hommes avant le début de l’intervention, nous avons émis l’hypothèse
que les hommes amélioreraient davantage leurs habitudes alimentaires que les
femmes en réponse à l’intervention nutritionnelle.
56
Le troisième objectif spécifique était de déterminer les changements dans les
facteurs de motivation en réponse à l’intervention nutritionnelle de 12 semaines et à
long terme, ainsi que leur association avec les changements dans l’adhésion à
l’alimentation méditerranéenne chez les hommes et les femmes distinctement.
Considérant qu’un comportement régulé via la motivation autodéterminée
semble favorable à l’adoption de saines habitudes alimentaires (Pelletier et al.,
2004), nos hypothèses étaient 1) que les hommes augmenteraient davantage leur
motivation autodéterminée en comparaison avec les femmes, et 2) qu’une
amélioration de la motivation autodéterminée serait associée à une meilleure
adhésion à l’alimentation méditerranéenne, à la fois chez les hommes et chez les
femmes.
Le quatrième objectif spécifique était de déterminer les différences entre les
hommes et les femmes quant aux changements anthropométriques, métaboliques et
de qualité de vie, en réponse à l’intervention nutritionnelle de 12 semaines et six mois
suivant la fin de l’intervention.
En tenant compte de l’hypothèse formulée à l’objectif 2, nous avons émis
l’hypothèse que les hommes bénéficient davantage d’un programme d’éducation
en nutrition visant l’adoption de l’alimentation méditerranéenne, via une
amélioration plus importante de leur profil métabolique et de leur niveau de
qualité de vie.
57
CHAPITRE 3 :
Différences relatives au genre dans les apports
alimentaires : quelle est la contribution des variables
motivationnelles?
Vicky Leblanc, Catherine Bégin, Louise Corneau, Sylvie Dodin, Simone Lemieux
Journal of Human Nutrition and Dietetics, 2015, Feb;28(1) :37-46.
59
Gender differences in dietary intakes: What is the contribution of motivational
variables?
Vicky Leblanc1, Catherine Bégin2, Louise Corneau1, Sylvie Dodin1,3, and Simone
Lemieux1.
1
Institute of Nutrition and Functional Foods, Laval University, 2440 Hochelaga Blvd,
Québec, Canada, G1V 0A6
2
School of Psychology, Laval University, Pavillon Félix-Antoine Savard, 2325 rue des
Bibliothèques, Québec, Canada, G1V 0A6
3
Department of Obstetric and Gynaecology, Laval University, Pavillon Ferdinand-Vandry,
1050 Medicine Avenue, Québec, Canada, G1V 0A6
Address of correspondence:
Simone Lemieux, Ph.D, RD.
Institute of Nutrition and Functional Foods
2440 Hochelaga Blvd
Laval University, Québec
Phone: (418) 656-2131 ext.: 3637
Fax: (418) 656-5877
E-mail: [email protected] (can be published)
Keywords : Self-Determination Theory, gender differences, basic psychological needs,
eating behaviors, energy density, body mass index.
Abbreviations: SDT, Self-Determination Theory; FSH, Follicle-stimulating hormone; C,
Cholesterol; SDI, Self-determination index; FFQ, Food frequency questionnaire; TFEQ,
Three-Factor Eating Questionnaire; BMI, Body mass index.
61
RÉSUMÉ
Cette étude visait à identifier les différences de genre dans les apports et comportements
alimentaires ainsi que pour les variables motivationnelles, puis à déterminer les
associations entre ces variables auprès d’hommes et de femmes préménopausées à risque de
maladies cardiovasculaires. L’échelle de régulation du comportement alimentaire a permis
d’évaluer la motivation autodéterminée spécifique au contexte alimentaire. Les apports
alimentaires ont été mesurés à partir d’un questionnaire de fréquence et le Three-Factor
Eating Questionnaire a permis d’évaluer les comportements alimentaires. Les hommes
présentaient des valeurs plus élevées pour l’apport énergétique, la densité énergétique, le
pourcentage de lipides et des valeurs plus faibles pour le pourcentage de glucides,
comparativement aux femmes. Des niveaux plus faibles de susceptibilité émotionnelle à la
désinhibition étaient observés chez les hommes. Les femmes présentaient une motivation
autodéterminée plus élevée que les hommes. Une association inverse entre la motivation
autodéterminée et la densité énergétique était observée chez les femmes seulement. Ces
résultats suggèrent que les différences entre les hommes et les femmes dans les apports
alimentaires pourraient s’expliquer par des associations distinctes entre la motivation
autodéterminée et les variables alimentaires selon le genre.
63
ABSTRACT
Differences between men and women in dietary intakes and eating behaviors have been
reported and could be explained by gender differences in motivational variables associated
with the regulation of food intake. Our main objectives were to identify gender differences
in dietary intakes, eating behaviors and motivational variables and to determine how
motivational variables were associated with dietary intakes and eating behaviors in men
and women. Sixty-four men and 59 premenopausal women were included in the study and
presented cardiovascular risk factors. The regulation of eating behaviors scale was
completed to assess motivational variables. A validated food frequency questionnaire was
administered to evaluate dietary intakes and subjects completed the Three-Factor Eating
questionnaire to assess eating behaviors. Men had higher energy intake, energy density and
percentage of energy from lipids and lower percentage of energy from carbohydrates than
women (P  0.04). Men also had a lower emotional susceptibility to disinhibition than
women (P = 0.0001). Women reported a higher score for eating related self-determined
motivation (i.e. eating related SDI) than men (P = 0.002). The most notable gender
difference in the pattern of associations was that eating related SDI was negatively
associated with energy density (r = -0.30; P = 0.02), only in women. Women had a better
dietary profile and higher eating related SDI than men. However, gender differences in
dietary variables might be explained by a potential gender specific pattern of association of
eating related SDI with dietary intakes and eating behaviors.
65
INTRODUCTION
Gender differences have been reported for dietary intakes and eating behaviors
(1)
. More
specifically, previous studies reported that women have higher fruit and vegetables
consumption and tend to have greater interest in healthy diets and desire to eat food lower
in calories than men
(2, 3)
. Gender differences in eating behaviors have also been reported,
women generally showing higher dietary restraint and disinhibition levels than men
(4)
. It
has been shown that disinhibition is positively associated with energy intake (5) and energy
density
(6)
whereas dietary restraint is generally negatively associated with energy intake
and dietary fat intakes (5, 7).
Motivation to adopt healthy eating is recognized as a potential factor involved in the
regulation of dietary intakes and eating behaviors
(8)
. Accordingly, the Self-Determination
Theory (SDT) (9, 10) emphasizes the importance of motivation quality and proposes that the
regulation of a behavior may take many forms that correspond to different behavioral
regulatory styles according to motivation, which differ by their self-determination level.
Another key postulate from the SDT addresses the processes that facilitate internalization
of nonself-determined regulatory styles towards more self-determined regulatory styles
(9,
10)
. Moreover, the SDT has identified three basic psychological needs which are autonomy,
competence, and relatedness that foster the process of internalization and development of
optimal motivation and personal well-being
(10)
. With regard to the regulation of eating
behaviors, Pelletier et al. (2004) showed that global self-determined motivation in life
predisposes individuals to adopt a more self-determined orientation in the regulation of
eating behaviors. Studies also showed that behaviors regulated by self-determined
motivation promote adoption of healthy eating behaviors and long-term maintenance of
healthy eating habits
(11, 12)
, and could also be a protective factor against social pressures
unfavourable to healthy eating behaviors
(11, 13)
. However, literature about the potential
influence of motivation on eating behaviors is scarce. In addition, according to the SDT, the
same behavior can be regulated differently between individuals
(14)
, which suggests that it
might not fulfill the same role in men and in women. Although gender differences related
67
to motivational factors have not been specifically investigated in a dietary context,
literature suggests that women generally display a more self-determined motivational
profile compared to men in a diversity of life domains, such as sports, leisure, interpersonal
relationships and education (15).
To our knowledge no study has yet investigated the contribution of motivational variables
in explaining gender differences in dietary intakes and eating behaviors. In addition, the
pattern of associations relating motivational variables to dietary intakes and eating
behaviors according to gender has never been documented. Moreover, while the adoption
of healthy eating habits is encouraged in the prevention of chronic diseases
(16)
, dietary
changes remain difficult to achieve for many individuals. In order to favour adherence to
healthy eating habits in men and women, we first need to get a better understanding of its
underlying factors using a gender specific approach. According to the literature, motivation
related to the regulation of food intake and eating behaviors is clearly one of these
underlying factors. In a context of intervention, it would thus be beneficial to identify
motivational factors influencing healthy eating according to gender, to promote optimal
support in dietary changes. The main objective of our study was therefore to identify
gender differences in dietary intakes, eating behaviors and motivational variables and to
verify whether some gender differences in motivational variables could explain differences
observed between men and women in dietary intakes and eating behaviors. We also wanted
to determine how motivational variables were associated with dietary intakes and eating
behaviors in men and women, separately.
METHODOLOGY
Participants
This study was conducted among a sample of 64 men and 59 premenopausal women aged
between 25 and 50 years old and presenting cardiovascular risk factors. Data presented in
68
this article correspond to baseline values from a nutritional intervention study aiming at
assessing changes in dietary variables in men and women in response to a nutritional
intervention promoting the Mediterranean diet (MedDiet). This latter study is a part of a
broader research project in which our research team was interested to document differences
between men and women in response to the MedDiet both in a controlled setting (i.e. all
meals adjusted to energy needs were provided to subjects for four weeks) and also in a
more real life intervention context (nutrition education program). When designing the study
we decided to focus on premenopausal women and to compare them to men in the same
age range because we wanted to maximize the potential impact of sex-related hormones on
metabolic changes observed in response to the MedDiet
(17)
. Therefore, in order to be able
to compare results obtained in a controlled setting to those obtained in the more real life
context we have used the same inclusion criteria.
In women, a follicle-stimulating hormone (FSH) measurement was performed if needed
(e.g., when women presented periods irregularities) to confirm the premenopausal status
(FSH < 20 IU/l) (18). Men and women included in the study had to present slightly elevated
LDL-Cholesterol (C) concentrations (between 3.0 and 4.9 mmol/L) (19) or a total-C to HDLC ratio ≥ 5.0, and at least one of the four following criteria of the metabolic syndrome
(16)
:
1) triglyceride concentrations ≥ 1.7 mmol/L; 2) fasting glycaemia between 6.1 et 6.9
mmol/L; 3) blood pressure concentrations ≥ 130/85 mm Hg; 4) waist circumference ≥ 80
cm in women and ≥ 94 cm in men (20). Participants also had to have a stable body weight (
2.5 kg) for a minimum of three months prior to the beginning of the study and to be
involved in food purchases and/or meal preparation at home. We excluded men and women
who had cardiovascular events and who used medication that could affect dependent
variables under study. Smokers, participants with an alcoholism history, pregnant women
and participants with a high Mediterranean score (Medscore > 29, concordant with a typical
Mediterranean food pattern)
(21)
were also excluded. Briefly, the Medscore (range between
0-44 points) was calculated based on the 11 components of the Mediterranean pyramid, i.e.
grains; fruits; vegetables; legumes, nuts and seeds; olive oil; dairy products; fish; poultry;
eggs; sweets and red meat/processed meat, and allowed to assess the level of adherence to
the Mediterranean food pattern, i.e. healthy dietary intakes. A high score for food groups
69
found at the bottom of the pyramid (e.g., legumes) reflects a high consumption whereas a
high score for food groups found at the top of the pyramid (e.g., red meat) reflects a low
consumption, as previously described
(21)
. In addition, men included in the study were
matched to women for LDL-C concentrations and age. All participants voluntarily agreed
to participate in the research project and were recruited through different media
advertisements in the Québec City Metropolitan area. This study was approved by the
Laval University Research Ethics Committee. Written informed consent was obtained from
all men and women prior to their participation in the study.
Measurements
Motivational variables
Basic psychological needs scale
(22)
is a 21-item questionnaire that assesses three basic
psychological needs, i.e. autonomy (7 items), competence (6 items) and relatedness (8
items), which are determinants of motivation according to Self-Determination Theory
(SDT) and mediate the impact of social factors on individual’s level of self-determined
motivation. More specifically, autonomy reflects a desire to engage in activities and to be
the origin of one’s own behavior; competence is defined as the need to interact effectively
with one’s environment to produce desired outcomes while preventing undesired events;
relatedness is defined as the need to feel connected to and accepted by significant others in
a social milieu
(22)
. Each item was measured on a 7-point Likert scale, which allowed
calculating three subscale scores corresponding to the satisfaction of each of the three
needs.
The Global motivation scale (GMS-28)
(15, 23)
is a questionnaire that assesses fundamental
motivation in life and displays high level of reliability and validity among the adult
population
(15)
. This scale includes 28 items and assesses intrinsic motivation (12 items)
(which refers to engaging in an activity for its own sake and experience of pleasure and
satisfaction derived from participation), identified regulation (4 items) (i.e. refers to
70
behaviors that are performed by choice because the individual judges them as important),
introjected regulation (4 items) (i.e. refers to behaviors that are in part internalized by the
person) and external regulation (4 items) (i.e. refers to behaviors that are not selfdetermined because they are regulated through external means such as rewards and
constraints), and amotivation (4 items) (i.e. pertains to the lack of intentionality and
therefore refers to the relative absence of motivation (neither intrinsic or extrinsic)). Each
item was measured on a 7-point Likert scale, which allowed calculation of the global selfdetermination index (SDI).
The Regulation of eating behaviors scale
(11)
is a 24-item validated questionnaire that
assesses self-determined motivation for the regulation of eating behaviors. Items included
in this questionnaire (4 items per self-determined regulatory styles) assess intrinsic
motivation (e.g., “I like to find new ways to create meals that are good for my health”),
different self-determined regulatory styles which are integrated (e.g., “Eating healthy is an
integral part of my life”), identified (e.g., “I believe it will eventually allow me to feel
better”), introjected (e.g., “I feel I must absolutely be thin”) and external (e.g., “Other
people close to me insist that I do”), and amotivation (e.g., “I don’t know why I bother”)
(10)
. Each item was measured on a 7-point Likert scale, which allowed calculation of the
eating related SDI (15), specific to eating regulation.
Dietary Variables
A validated food frequency questionnaire (FFQ)
(24)
was administered to participants. The
FFQ is based on typical foods available in Québec, contains 91 items and 33 subquestions
and was administered by a registered dietitian. Participants were questioned about the
frequency of intake for different foods and drinks during the last month and could report
the frequency of these intakes in terms of day, week or month. Macronutrient and
micronutrient intakes obtained from the FFQ were evaluated using the Nutrition Data
System for Research (NDS-R, version 4.03_31) software.
71
Eating Behaviors and Meal Preparation Frequency
Eating behaviors were assessed by the Three-Factor Eating questionnaire (TFEQ) (25), a 51item validated questionnaire which assesses three factors that refer to cognitions and
behaviors associated with eating: dietary restraint (21 items) (conscious control of food
intake with concerns about shape and weight), disinhibition (16 items) (overconsumption of
food in response to a variety of stimuli associated with a loss of control on food intake) and
hunger (14 items) (food intake in response to feelings and perceptions of hunger). More
specific subscales are also derived from these three general eating behaviors
(26, 27)
: rigid
restraint, flexible restraint, habitual susceptibility to disinhibition, emotional susceptibility
to disinhibition, situational susceptibility to disinhibition, internal hunger, and external
hunger (see Table 2). As for involvement in meal preparation, referring to active
involvement in meal organization and preparation, participants had to complete a
questionnaire where the following question was asked: “ Considering that there are 14
meals in a week (taking into account lunch and dinner only), how many times per week are
you involved in meal preparation?” Participants had to choose among categories defined as
follow: Never, 1-3 time(s)/week, 4-6 times/week, 7-9 times/week, 10-12 times/week and
13-14 times/week, which allowed to assess weekly frequency in meal preparation.
Anthropometric and Metabolic Profile
All anthropometric and metabolic variables were measured in the fasting state. According
to standardized procedures
(28)
height was measured to the nearest millimeter with a
stadiometer (Seca 222 Mechanical Telescopic Stadiometer), body weight was measured to
the nearest 0.1 kg on a calibrated balance (BWB-800S Digital scale, Tanita), and body
mass index (BMI) was then calculated. Waist circumference measure was also taken to the
nearest millimeter according to standardized procedures
(28)
. Percentage of body fat was
estimated using the Tanita body-fat analyser (Tanita-BC-418 body-fat analyser, Tanita
Corp., Tokyo, Japan). Basic lipid profile and glucose and insulin levels were measured with
a blood sample taken after a 12-hour overnight fast.
72
Statistical Analyses
Student’s t-test allowed comparisons of characteristics related to motivational variables,
dietary intakes, eating behaviors, and anthropometric and metabolic profile, whereas the
Fisher’s Exact test was performed to compare weekly frequency of meal preparation
(categorical data) between men and women. The Fisher’s Exact test was also performed to
compare weekly frequency of meal preparation between men and women individually
matched for their level of eating related SDI (largest difference within pair set at 3 units of
SDI). For variables not normally distributed, a transformation was performed. However,
these variables are presented as raw data in the tables. Pearson correlation analyses were
performed to examine the association between global SDI and eating related SDI, and also
in order to examine how eating related SDI was associated with dietary intakes and eating
behaviors. A covariance analysis (Lsmean procedure) was performed in order to determine
if gender differences in dietary intakes were still significant when accounting for eating
related SDI. The probability level for significance used for the interpretation of all
statistical analyses was set at a  level of P ≤ 0.05. All analyses were performed using SAS
statistical software (version 9.2, SAS Institute Inc., Cary, NC).
RESULTS
Table 1 shows characteristics of men and women in terms of their age, anthropometric
variables and metabolic profile. Men and women included in our study were about the same
age and had similar levels of total-C, LDL-C, fasting glucose and fasting insulin, but men
had higher BMI, waist circumference, total-C to HDL-C ratio and triglyceride levels than
women, whereas women had higher percentage of body fat and HDL-C levels than men.
Table 2 presents dietary intakes and eating behaviors in men and women. Men had higher
energy intake, energy density and percentage of energy provided by lipids while they had
lower percentage of energy provided by carbohydrates than women. In addition, 43.8%,
73
28.1% and 100% of men and 57.6%, 42.4% and 100% of women had respectively lipid,
carbohydrate and protein intakes within acceptable macronutrient distribution range.
According to meal preparation, men had a lower weekly frequency of meal preparation than
women (P  0.0001), with 4.7% versus 22.0% of men and women respectively, reporting a
frequency of meal preparation between 13-14 times a week. As for eating behaviors
measured with the TFEQ, the only significant gender difference observed was a lower score
for emotional susceptibility to disinhibition in men than in women.
Table 3 shows basic psychological needs and motivational profile in men and women. No
gender differences were observed for basic psychological needs for autonomy, competence
and relatedness, and for the global SDI and its respective subscales. As for the regulation of
eating behaviors scale represented by the eating related SDI, men reported a significantly
lower score in eating related SDI than women. More specifically, intrinsic motivation and
integrated regulation were lower in men than in women. Pearson’s correlation analyses
were conducted to determine if there were significant associations between the global and
the eating related SDI, in men and women. A significant and positive association between
the global and the eating related SDI was observed in men (r = 0.50; P  0.0001) as well as
in women (r = 0.53; P  0.0001). Analyses were also performed to verify whether some
gender differences in eating related SDI could explain differences observed between men
and women in dietary intakes. Accordingly, gender differences in energy density and
percentage of energy provided by carbohydrates remained significant after statistical
adjustment for eating related SDI (Lsmean P  0.02). However, gender difference in the
percentage of energy provided by lipids was no longer significant (Lsmean = 0.08) after
adjustment for eating related SDI. In order to verify whether gender differences in eating
related SDI could explain the difference observed between men and women as regard to
weekly frequency of meal preparation, we individually matched men and women with
similar eating related SDI. After this procedure it was found that mean eating related SDI
levels were respectively 23.12  6.26 in men and 23.11  6.28 in women (t-test, P = 0.99).
Then with a total of 42 pairs formed, results showed that a significant gender difference
remained for weekly frequency of meal preparation, with men presenting lower weekly
frequency of meal preparation than women (Fisher’s Exact test, P = 0.003).
74
Correlation analyses were conducted to determine how eating related self-determined
motivation was associated with dietary intakes and eating behaviors, in men and women.
Table 4 shows that except for the significant and negative association between eating
related SDI and energy density in women, no other dietary variables were associated with
eating related SDI among men and women. However, for eating behaviors among men,
eating related SDI was significantly and positively associated with flexible restraint, but
negatively associated with emotional susceptibility to disinhibition and hunger, more
specifically with internal hunger. It was also found that eating related SDI was negatively
associated with percentage of body fat. In women, eating related SDI was significantly and
negatively associated with disinhibition, more precisely with situational susceptibility to
disinhibition. A trend for negative associations between eating related SDI and emotional
susceptibility to disinhibition were also observed in women. Moreover, eating related SDI
was also negatively associated with BMI, percentage of body fat and waist circumference
in women.
DISCUSSION
Our results suggest that women reported a healthier dietary profile, namely lower energy
density, and also had globally a healthier metabolic profile than men. Previous studies
support our results by showing that women tend to have better overall diet quality than men
(29, 30)
. Furthermore, studies showed that dietary intakes of low energy density are
associated with a better quality of dietary intakes and a lower BMI
(31, 32)
and evidence of
the beneficial influence of healthy eating habits on health status are well established in the
literature (33, 34). This brings support to the observation that the lower energy density in the
diet of women was accompanied by a lower BMI and by a healthier lipid profile than what
was found in men. As for eating behaviors, the only gender difference was for emotional
susceptibility to disinhibition with women having higher level than men. A similar
difference was previously shown in other studies (35, 36).
75
According to motivational profile, men and women reported similar basic psychological
needs satisfaction and similar level of global self-determined motivation. In addition, our
results suggest that for both genders, a higher level of global self-determined motivation in
life domains is associated with a higher level of eating related self-determined motivation.
However, our results also showed that for a given level of global self-determined
motivation, women show higher level of eating related self-determined motivation than
men. One of the postulates of the SDT indicates that motivation is determined by the topdown effect from motivation at the next level up in the hierarchy, respectively, the global,
contextual and situational motivation
(15)
. In fact, this postulate proposes that higher
hierarchical level of motivation can influence the level below. Although our study does not
allow establishing causal associations, it could be hypothesized that global self-determined
motivation can influence the level of eating related self-determined motivation in both men
and women. However, because no gender differences were observed according to global
SDI, other factors are clearly involved in determining the level of eating related selfdetermined motivation and could explain the difference in eating related SDI between men
and women.
According to the SDT, more self-determined forms of behavioral regulation will be
promoted if the basic psychological needs are satisfied
(10)
. Despite the lack of gender
differences in basic psychological needs at the global level, it is possible, based on the
hierarchical model of motivation proposed by Vallerand (1997), that gender differences
exist in basic psychological needs satisfaction, more specifically related to dietary
behaviors. The level of satisfaction of these psychological needs could influence eating
related level of self-determined motivation, i.e. dietary self-determined motivation, but also
ultimately the behavior, i.e. meal preparation and dietary intakes. Questionnaires evaluating
basic psychological needs related to satisfaction at work
(37)
and in relationships
(38)
have
been previously developed, but no such questionnaire exists for dietary behaviors.
Therefore, it would be of interest to develop a tool to assess basic psychological needs
more specifically related to dietary behavior in order to test this hypothesis.
76
Overall, our results indicate that women had higher level of eating related self-determined
motivation and a diet of better quality than men, which agree with previous study indicating
that higher level of self-determined motivation or motivation more autonomously regulated
is associated with dietary intakes of better quality
(11)
. Other gender-related factors than
gender differences in eating related SDI seem to be involved in determining dietary intakes
and behaviors since analyses performed indicated that when men and women where
compared while adjusting for eating related SDI women still had a lower energy density, a
higher percentage of energy provided by carbohydrates and a higher frequency of meal
preparation than men. For example, it is possible that factors such as nutrition knowledge
(39)
and attitudes
(40)
might explain some gender differences in dietary intakes and eating
behaviors.
The pattern of associations of eating related SDI with dietary intakes and eating behaviors
was investigated in men and women. Globally, our results agree with the literature
indicating that a higher self-determined motivation was associated with better dietary
profile and with eating behaviors predisposing to a healthier body weight management
(41,
42)
. The most notable difference between men and women in the pattern of associations was
that eating related SDI was significantly associated to dietary intakes, only in women. In
fact, eating related SDI was associated with lower energy density in women only. Thus,
level of self-determined motivation appears to be translated into concrete actions to modify
eating habits in women, which is not the case in men. This gender difference in the
association between eating related SDI and dietary intakes (i.e. association in women and
not in men) suggest that even if men were increasing their eating related SDI, this would
not necessarily allow matching-up the quality of the dietary profile observed in women.
Results of our covariance analyses showing that gender differences in dietary intakes were
still observed after adjustment for eating related SDI bring support to this suggestion.
Intervention studies aiming at increasing eating related SDI in men and women will be
needed to properly test this hypothesis.
In terms of clinical implications, our study allowed characterizing motivational profile,
dietary intakes and eating behaviors in men and women presenting cardiovascular risk
77
factors and is therefore a first step toward a better understanding of factors that could
potentially help developing efficacious interventions aimed at promoting healthier eating
habits and eating behaviors in a preventive health care context
(43)
. From our study, we are
confident that intervention favouring an increase in eating related SDI will be beneficial for
men and women but it can be suspected, according to our results, that changes in dietary
intakes and eating behaviors in response to such an intervention will not be the same in
men and women. Future intervention studies should be addressed to clarify how
individual’s motivation related to healthy eating can impact on nutritional intervention
outcomes, and identify potential gender differences in this regard. Moreover, intervention
studies designed to favour an optimal motivational profile in men and women are also
needed.
Some limitations of the study need to be mentioned. First, our sample of men and women
represents individuals with cardiovascular risk factors, which is not representative of the
general population. Although anthropometric and metabolic variables were measured,
dietary intakes were self-reported which cannot exclude the risk of misreporting dietary
intakes. Nevertheless, our study has important strengths namely the fact that analyses were
conducted distinctively in men and women according to motivational and behavioral
variables, and dietary intakes. It is also the first study that has closely examined the
associations of motivational profile with dietary intakes and eating behaviors, specifically
targeting individuals presenting cardiovascular risk factors and who could therefore clearly
benefit from improving their eating habits.
In conclusion, although men and women showed similar level of global self-determined
motivation in life domains, women presented higher level of eating related self-determined
motivation than did men. According to our results, the more favourable dietary profile
observed in women could not be solely attributed to their higher level of eating related SDI.
This observation might be explained by the fact that the pattern of associations of eating
related SDI with dietary variables and eating behaviors was not the same in men and
women.
78
FINANCIAL SUPPORT
This research project was supported by the Canadian Institutes of Health Research (MOP
84568) and Heart and Stroke Foundation of Quebec (2007-180). Canadian Institutes of
Health Research and Heart and Stroke Foundation of Quebec had no role in the study
design, collection, analysis or interpretation of the data, writing the manuscript, or the
decision to submit the paper for publication. V.L. is a recipient of a doctoral scholarship
from the Fonds de recherche du Québec - Santé (FRQS).
AUTHORSHIP
The authors’ contributions are as follow: V.L. was in charge of the analysis and
interpretation of data and drafted the manuscript; C.B. contributed to the conception and
design of the study as well as to the interpretation of data; L.C. and S.D. contributed to the
conception and design of the study; S.L. (corresponding author) was responsible for the
conception and design of the study and contributed to the interpretation of data. All of the
authors have read and approved the final version of the manuscript submitted for
publication.
CONFLICT OF INTEREST
Authors report no conflict of interest.
79
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83
Table 1. Physiological characteristics of men and women
Men (n=64)
Women (n=59)
Variables
Mean
SD
Mean
SD
t
Age (years)
41.0
7.9
41.8
6.7
0.60
Body weight (kg)
96.6
15.5
77.9*
16.6
7.50
2
Body mass index (kg/m )
30.8
4.4
29.6*
6.0
2.10
Body fat (%)
26.7
4.5
39.2*
6.2
11.46
Waist circumference (cm)
106.1
10.2
95.8*
11.5
-5.53
Total cholesterol (C) (mmol/L)
5.7
0.8
5.8
0.7
0.87
LDL-C (mmol/L)
3.6
0.7
3.6
0.7
0.07
HDL-C (mmol/L)
1.1
0.2
1.4*
0.3
6.06
Total-C/HDL-C ratio
5.1
1.0
4.2*
0.9
-5.37
Triglycerides (mmol/L)
1.9
0.9
1.5*
0.6
-2.95
Fasting glucose (mmol/L)
5.3
0.5
5.2
0.7
1.34
Fasting insulin (pmol/L)
100.5
45.0
88.5
45.4
-1.79
Analyses are based on Student’s t-test procedure in SAS.
For lipid-lipoprotein variables, glycaemia and insulinaemia, n = 63 men and n = 58 women.
For percentage of body fat, n = 52 men and n = 48 women.
*Values significantly different between men and women (P ≤ 0.05).
HDL, high-density lipoprotein; LDL, low-density lipoprotein.
85
Table 2. Dietary intakes and eating behaviors in men and women
Variables
Men (n=64)
Mean
SD
Women (n=59)
Mean
SD
Dietary intakes
Energy intake (kJ)
Energy density (kJ/g)
Carbohydrates (% of total energy)
Proteins (% of total energy)
Lipids (% of total energy)
12824
5.52
42.2
18.3
36.8
10280*
5.06*
44.5*
17.8
35.1*
3749
1.00
5.3
2.5
4.8
2389
0.71
5.8
2.8
4.5
t
-4.60
-3.05
2.33
-1.19
-2.06
Eating behaviors
Dietary restraint
5.9
3.2
6.9
4.1
1.18
Flexible restraint
1.9
1.4
2.4
1.6
1.76
Rigid restraint
1.7
1.3
1.8
1.7
0.46
Disinhibition
6.0
2.8
6.2
2.8
0.48
Habitual susceptibility to disinhibition
0.7
1.0
0.7
1.0
0.12
Situational susceptibility to disinhibition
3.0
1.4
2.5
1.5
-1.84
Emotional susceptibility to disinhibition
0.7
1.0
1.6*
1.2
3.98
Hunger
4.8
3.0
4.2
2.9
-1.12
Internal hunger
1.9
1.8
1.6
1.6
-1.16
External hunger
1.9
1.5
1.8
1.4
-0.10
For the TFEQ completion, n = 63 men; for flexible restraint, n = 60 men and n = 58 women; for
rigid restraint, n = 57 women; for habitual susceptibility to disinhibition, n = 58 women; for
internal hunger, n=60 men and n=58 women; for external hunger, n=62 men and n = 58 women.
For the TFEQ completion, n = 63 men; for flexible restraint, n = 60 men and n = 58 women; for
rigid restraint, n = 57 women; for habitual susceptibility to disinhibition, n = 58 women; for
internal hunger, n=60 men and n=58 women; for external hunger, n=62 men and n = 58 women.
86
Table 3. Basic psychological needs, global and eating related motivation in men and
women
Variables
Basic psychological needs
Autonomy
Competence
Relatedness
Global motivation scale
Global self-determination index
Men (n=63)
Mean
SD
Women (n=59)
Mean
SD
t
5.44
5.66
5.49
0.72
0.74
0.67
5.31
5.59
5.55
0.82
0.74
0.82
-0.91
-0.57
0.44
8.55
3.21
8.20
3.61
-0.57
Regulation of eating behaviors scale
Intrinsic motivation
5.27
1.05
5.78*
0.87
2.96
Integrated regulation
4.88
1.18
5.32*
1.04
2.15
Identified regulation
6.23
0.70
6.33
0.64
0.81
Introjected regulation
2.35
1.01
2.30
0.93
-0.28
External regulation
1.95
1.05
1.63
0.72
-1.83
Amotivation
1.38
0.49
1.22
0.42
1.86
Eating related self-determination index
21.33
6.43
25.08*
6.58
3.18
For the questionnaire on basic psychological needs, n = 63 men; for the global motivation
scale, n = 63 men and n = 58 women; for the regulation of eating behaviours scale, n = 63
men; for integrated regulation, n = 62 men; for identified regulation, n = 58 women.
87
Table 4. Association between eating related self-determination index and dietary intakes, eating
behaviors and anthropometric profile in men and women
Eating related self-determination index
Men (n=63)
Variables
r
Women (n=59)
p
Dietary intakes
Energy intake (kJ)
0.12
0.34
Energy density (kJ/g)
-0.06
0.64
Carbohydrates (% of total energy)
-0.01
0.92
Proteins (% of total energy)
0.11
0.38
Lipids (% of total energy)
-0.08
0.54
Eating behaviors
Dietary restraint
0.09
0.50
Flexible restraint
0.33
0.01
Rigid restraint
0.01
0.93
Disinhibition
-0.15
0.24
Habitual susceptibility to disinhibition
-0.07
0.60
Situational susceptibility to disinhibition
-0.05
0.70
Emotional susceptibility to disinhibition
-0.35
0.005
Hunger
-0.27
0.03
Internal hunger
-0.30
0.02
External hunger
-0.12
0.33
Anthropometric profile
Body mass index (kg/m2)
-0.12
0.34
Body fat (%)
-0.31
0.03
-0.17
0.19
Analyses are based on the Pearson correlation procedure in SAS.
88
r
p
-0.16
-0.30
-0.13
0.11
-0.007
0.23
0.02
0.32
0.39
0.96
-0.0005
0.09
-0.04
-0.26
-0.09
-0.25
-0.25
-0.18
-0.12
-0.25
1.00
0.52
0.74
0.04
0.49
0.05
0.06
0.18
0.37
0.06
-0.33
-0.43
-0.30
0.01
0.002
0.02
CHAPITRE 4 :
Différences entre les hommes et les femmes dans les
apports alimentaires et le profil métabolique en réponse
à une intervention nutritionnelle de 12 semaines visant
l’adoption de l’alimentation méditerranéenne
Vicky Leblanc, Anne-Marie Hudon, Marie-Michelle Royer, Louise Corneau, Sylvie Dodin,
Catherine Bégin, Simone Lemieux
Journal of Nutritional Science, 2015 ; 4(e13) : 1-11.
89
Differences between men and women in dietary intakes and metabolic profile in
response to a 12-week nutritional intervention promoting the Mediterranean diet
Vicky Leblanc1, Anne-Marie Hudon1, Marie-Michelle Royer1, Louise Corneau1, Sylvie
Dodin1,2, Catherine Bégin3, and Simone Lemieux1.
1
2
3
2440 Hochelaga Blvd
Phone: (418) 656-2131 ext.: 3637
Fax: (418) 656-5877
Key words: Differences between men and women, Mediterranean diet, Cardiovascular
risk, Self-Determination Theory.
Abbreviations: MedDiet, Mediterranean diet; CVD, Cardiovascular diseases; C,
Cholesterol; SDT, Self-Determination Theory; FSH, Follicle-stimulating hormone;
Medscore, Mediterranean score; MI, Motivational interviewing; FFQ, Food frequency
questionnaire; BMI, Body mass index; VAS, Visual analog scale.
91
RÉSUMÉ
Cette étude avait pour objectif de documenter les différences de genre dans les
changements alimentaires, anthropométriques et métaboliques en réponse à une
intervention nutritionnelle visant l’adoption de l’alimentation méditerranéenne et basée sur
la théorie de l’autodétermination. Soixante-quatre hommes et 59 femmes préménopausées à
risque de maladies cardiovasculaires ont pris part à l’intervention de 12 semaines. Les
apports alimentaires ont été évalués via un questionnaire de fréquence, à partir duquel un
score méditerranéen a été calculé. Une augmentation similaire du score méditerranéen a été
observée chez les hommes et les femmes en réponse à l’intervention. Les hommes ont
davantage diminué leur consommation de viandes rouges et augmenté leur consommation
de fruits comparativement aux femmes. Des diminutions similaires de l’IMC et de la
circonférence de la taille ont été observées chez les hommes et les femmes. Des
diminutions plus importantes des ratios C-total sur C-HDL et triglycérides sur C-HDL ont
été notées chez les hommes comparativement aux femmes, mais ces différences devenaient
non significatives après l’ajustement pour la valeur de départ. Ces résultats suggèrent que
l’intervention a mené à une amélioration plus importante des apports alimentaires et du
profil métabolique chez les hommes que chez les femmes. Le profil métabolique plus
détérioré chez les hommes au départ semble expliquer en majeure partie l’amélioration plus
importante des facteurs de risque cardiovasculaire chez les hommes.
93
ABSTRACT
Few studies have compared men and women in response to nutritional interventions but
none has assessed differences between men and women in the response to a nutritional
intervention program based on the Self-Determination Theory (SDT) and using the
Mediterranean diet (MedDiet) as a model of healthy eating, in a context of cardiovascular
diseases (CVD) prevention and within a non-Mediterranean population. Our study aimed to
document differences between men and women in changes in dietary, anthropometric and
metabolic variables, in response to a nutritional intervention program promoting the
adoption of the MedDiet and based on the SDT. Sixty-four men and fifty-nine
premenopausal women presenting risk factors for CVD were recruited through different
media advertisements in the Québec City Metropolitan area (Canada). The 12-week
nutritional program used a motivational interviewing approach and included individual and
group sessions. A validated food frequency questionnaire (FFQ) was administered to
evaluate dietary intakes from which a Mediterranean score (Medscore) was derived. Both
men and women significantly increased their Medscore in response to the intervention (P <
0·0001). Men showed a significantly greater decrease in red and processed meat (-0·4 (95%
CI, -0·7 to -0·1) portions/d) and a greater increase in fruit (0·9 (95% CI, 0·2 to 1·6)
portion/d) intakes than women. When adjusting for the baseline value of the response
variable, differences between men and women became non significant for red and
processed meat and fruit intakes whereas significant differences between men and women
(i.e. larger increases in men than women) were observed for legumes, nuts and seeds (0·6
(95% CI, 0·2 to 1·0) portion/d) and whole grain products (0·5 (95% CI, 0·01 to 1·0)
portion/d) intakes. Significant decreases were observed for BMI and waist circumference in
both men and women (P  0·04). Significant greater decreases were found for total-C to
HDL-C (-0·2 (95% CI, -0·4 to -0·03)) and triacylglycerols to HDL-C (-0·2 (95% CI, -0·4
to -0·04)) ratios in men than in women. For metabolic variables, differences between men
and women became non significant for total-C to HDL-C and triacylglycerols to HDL-C
ratios when adjusted for the baseline value of the response variable. Our results suggest that
the nutritional intervention promoting the adoption of the MedDiet and based on the SDT
led to greater improvements in dietary intakes in men than in women, which appear to have
95
contributed to beneficial anthropometric and metabolic changes, more particularly in men.
However, the more deteriorated metabolic profile found in men at baseline seems to
contribute to a large extent to the more beneficial changes in CVD risk factors observed in
men as compared to women.
96
INTRODUCTION
Adoption of healthy eating habits is encouraged in the context of chronic disease
prevention and the Mediterranean diet (MedDiet) has been ranked as one of the best models
to provide protection against cardiovascular diseases (CVD)
(1-3)
. The MedDiet pattern is
characterized by a high intake of vegetables, fruits, legumes, nuts, cereals (mainly
unrefined), a high intake of olive oil, a low-to-moderate intake of dairy products, a low
intake of meat and poultry, and a regular but moderate intake of alcohol, primarily in the
form of wine and generally during meals (3).
Studying differences between men and women in response to interventions aimed at
preventing or treating diseases is absolutely essential for providing optimal care to men and
women. Without such studies comparing men and women, we would not know, for
example, that usage of some medications for preventing or treating CVD are efficacious in
men but not appropriate in women
(4, 5)
. At this point it is essential to underline that
differences observed between men and women can be explained by both sex and gender
differences. Sex differences refer to biological and physiological characteristics that
distinguish males from females while gender is described as socially constructed roles,
relationships, behaviors, relative to power, and other traits that societies ascribe to men and
women
(6)
. When studying differences between men and women in response to nutritional
interventions, both sex and gender differences can be involved to a different degree
depending upon the type of intervention and the two constructs have been suggested to be
closely interrelated and difficult to dissociate (6).
Some studies have documented differences between men and women in the context of
controlled studies where all food and drinks are provided. In such a context, differences
observed between men and women in response to the intervention refer more to sex than to
gender differences (7-9). In fact, in those types of studies the impact of the diet on metabolic
variables measured can be influenced by sex-related factors such as sexual hormones
(10)
and is not likely to be influenced by factors such as diet adherence that is in turn modulated
97
by gender-related factors. A few studies have been performed to compare men and women
in response to diet manipulations performed in controlled conditions. Accordingly, a
greater decrease has been reported in LDL-Cholesterol (C) levels in response to a low
saturated fatty acids diet in men than in women (8, 9, 11) and a recent study published by our
team showed decreases in insulin levels in men but not in women, in response to a 4-week
MedDiet
(7)
. On the other hand, in nutritional interventions during which subjects continue
to buy their food, cook their meals and make decisions about what they eat, the differences
observed between men and women cannot be considered as sex differences since gender
specific factors such as attitudes, beliefs and motivation towards food regulation are
influencing adherence to dietary recommendations and therefore health benefits that can be
obtained from it. This is why when referring to these types of studies the term gender
differences is more appropriate.
Only a few studies have been performed to assess gender differences in response to
educational nutrition program promoting the MedDiet. Among a Mediterranean population,
a higher success in improving adherence to the MedDiet in men than women was reported
after one year in the PREDIMED trial, which includes Spanish men and women presenting
high risk for CVD
(12)
. Among a non-Mediterranean population, a study has reported the
impact of a MedDiet education program in hypercholesterolemic men and women and
showed that whereas women improved their dietary intakes in accordance with the
education program and significantly decreased their total-C levels, no such changes serum
total-C were observed in men. (13).
Changing eating habits represents a major challenge for many people
(14)
and evidence
indicates that the extent to which health professionals involve their clients in the decision
making process may influence adherence to treatment
(15)
. In this regard, the Self-
Determination Theory (SDT) suggests that stimulating optimal quality of motivation could
help individuals to evolve toward healthier eating habits. (16). To the best of our knowledge,
no study has assessed differences between men and women in the response to a nutritional
intervention program based on the SDT and using the MedDiet as a model of healthy
eating, in a context of CVD prevention and within a non-Mediterranean population.
98
Therefore, the objective of this study was to determine differences between men and
women in changes in dietary, anthropometric and metabolic variables, in response to a 12week nutritional intervention program promoting the adoption of the MedDiet, based on the
SDT, in Canadian men and women presenting risk factors for CVD.
METHODOLOGY
Participants
between 25 and 50 years old, and were recruited through different media advertisements in
the Québec City Metropolitan area (Canada). In women, a follicle-stimulating hormone
(FSH) measurement was performed if needed (e.g., when women presented menstrual
irregularities) to confirm the premenopausal status (FSH < 20 IU/l)
(17)
. Men and women
had to present slightly elevated LDL-C concentrations (between 3·0 and 4·9 mmol/l) (18) or
a total-C to HDL-C ratio ≥ 5·0, and at least one of the four following criteria of the
metabolic syndrome
(19)
: 1) triacylglycerol concentrations ≥ 1·7 mmol/l; 2) fasting
glycaemia between 6·1 et 6·9 mmol/l; 3) blood pressure measurements ≥ 130/85 mm Hg;
4) waist circumference ≥ 80 cm in women and ≥ 94 cm in men (20). Participants also had to
have a stable body weight ( 2·5 kg) for a minimum of three months prior to the beginning
of the study and to be involved in food purchases and/or preparation at home. We excluded
men and women who had cardiovascular events and who used medication that could affect
dependent variables under study, i.e., medication for hypertension, dyslipidemia and
diabetes (type 1 and type 2). Pregnant women, smokers, participants with an alcoholism
history or with a high Mediterranean score (Medscore > 29, i.e. food pattern already highly
concordant with the MedDiet) (21) were also excluded. This study was conducted according
to the guidelines laid down in the Declaration of Helsinki and all procedures involving
human subjects were approved by the Laval University Research Ethics Committee on
human experimentation. All subjects voluntarily agreed to participate in the research
99
project and written informed consent was obtained from all men and women prior to their
participation in the study. This clinical trial was registered at www.clinicaltrials.gov as
NCT01852721.
Study Design
The 12-week nutritional program was based on the Self-Determination Theory (SDT) and
used a motivational interviewing (MI) approach. The SDT relies on the quality of the
motivation that regulates behaviours, which lies on a continuum from lower to higher selfdetermined motivation forms (extending from amotivation to intrinsic motivation)
(22)
. The
SDT also postulates that the key component for the development of intrinsic motivation is
the satisfaction of basic psychological needs which are autonomy, competence and
relatedness
(22)
. The study was conducted in five phases (spanning from January 2010 to
November 2012) and the nutritional intervention included three group sessions (with 10-15
individuals each), three individual sessions and four follow-up phone calls with a registered
dietitian (Figure 1). Three registered dietitians were trained to provide a standardized
intervention and participants always met with the same dietitian during individual sessions.
The first group session was a lecture, always provided by the same dietitian and aiming at
explaining principles of the traditional MedDiet (length: 2·5 hours, n = 13-25
participants/group). At week four, men and women actively participated to a 3-hour
Mediterranean cooking lesson during which they had to cook a Mediterranean meal (n = 814 participants/group). At week eight, they shared a 3-hour Mediterranean potluck dinner
aimed at discussing barriers met in adopting dietary recommendations since the beginning
of the intervention (n = 5-12 participants/group). Individual counselling took place at weeks
one, five and 10 and lasted between 45 minutes and one hour for each appointment.
Individual follow-up phone calls took place at weeks three, six, nine and 12, and each
lasted for about 20-30 minutes. The main objective of individual counselling and follow-up
telephone calls was to assess dietary changes and to determine progressive personal goals
aimed at improving the adherence to MedDiet principles. Different tools such as the
decisional balance and the action plan, congruent with the MI approach, were used during
100
the individual sessions to formulate dietary objectives while increasing self-determined
motivation. In accordance with the SDT
(22)
, basic psychological needs (i.e. autonomy,
competence and relatedness) were promoted during the nutritional intervention via the MI
approach in order to increase self-determined motivation. More specifically, autonomy and
competence of men and women were promoted by the dietitian during individual sessions,
i.e. in supporting them into their decision making process about dietary changes and
potential strategies to achieve and maintain these changes, but also during the group
sessions by improving their cooking skills and knowledge related to food and nutrition.
Therefore, the dietitian had a client-centered approach and put no pressure on participants
about the type of dietary objectives to be chosen. In addition, no emphasis was put on body
weight control. Men and women were encouraged to maintain dietary changes in an
autonomous way at the end of the nutritional program and there was no additional contact
with the dietitian after the end of the 12-week intervention.
Measurements of Dependent Variables
All measurements were performed before (t = 0) and after the 12-week nutritional
intervention program (t = 12 weeks), except for the perceived adherence to the MedDiet
which was assessed only at the end of the intervention (t = 12 weeks).
Dietary Variables
(23)
was administered by a registered
dietitian. The FFQ is based on typical foods available in Québec. It contains 91 items and
33 subquestions. Participants were questioned about the frequency of intake of different
foods and drinks during the last month and could report the frequency of these intakes in
terms of day, week or month. A Medscore
(21)
was calculated based on the FFQ and
allowed to assess the level of adherence to the Mediterranean food pattern. A partial score
varying from 0 to 4 is attributed to each of the 11 components of the Mediterranean
pyramid. The Medscore could therefore vary between 0 and 44 points. Components of the
101
Medscore are: grains (whole and refined); vegetables (whole and juices); fruits (whole and
juices); legumes, nuts and seeds; olive oil (including olives and rapeseed oil); dairy
products; fish (including seafoods); poultry; eggs; sweets and red meat/processed meat. As
previously described
(21)
, a high consumption of food groups promoted by the
Mediterranean diet (grains, vegetables, fruits, legumes, nuts and seeds, olive oil and fish)
contributed to increase the Medscore, whereas a high consumption of food groups less
concordant with the Mediterranean diet (sweets and red meat/processed meat) contributed
to decrease the Medscore. Moreover, a moderate consumption of dairy products, poultry
and eggs obtained the maximum possible score for the respective component. A maximum
of one point was respectively attributed to refined grains, vegetable juice, fruit juice
consumption and intake of rapeseed oil or margarine made from olive or rapeseed oil.
Macronutrient and micronutrient intakes obtained from the FFQ were evaluated using the
Nutrition Data System for Research (NDS-R, version 4.03_31) software.
Anthropometric and Metabolic Profile
According to standardized procedures
(24)
height was measured to the nearest millimeter
with a stadiometer (Seca 222 Mechanical Telescopic Stadiometer), body weight was
measured to the nearest 0·1 kg on a calibrated balance (BWB-800S Digital scale, Tanita),
and body mass index (BMI) was then calculated. Waist circumference measure was also
taken to the nearest millimeter according to standardized procedures
(24)
. Body fat
percentage was estimated using the Tanita body-fat analyser, with the accuracy level being
+/- 5% of the institutional standard of body composition analysis-Dual Energy X-ray
Absorptiometry (DEXA) and repeatable to within +/- 1% variation when used under
consistent conditions (Tanita-BC-418 body-fat analyser (Tanita Corp., Tokyo, Japan)).
Blood samples were collected after a 12-hour overnight fast. Total-C, HDL-C and
triacylglycerol concentrations in serum were measured using commercial reagents on a
Modular P chemistry analyzer (with 0·8% and 1·7% of within and between assay precision,
respectively) (Roche Diagnostics, Mannheim, Germany). Serum LDL-C concentrations
were obtained by calculation using the Friedewald equation
(25)
and apolipoprotein B
concentrations by immunoturbidimetry (with < 1·5% and < 2·5% of within and between
assay precision, respectively) (Roche Diagnostics, Mannheim, Germany). Plasma glucose
102
concentrations were measured with the hexokinase enzymatic method (with 0·7% and <
1·2% of within and between assay precision, respectively) and plasma insulin
concentrations by electrochimiluminescence (with < 2·0% and < 2·8% of within and
between assay precision, respectively) (Roche Diagnostics, Mannheim, Germany). Systolic
and diastolic blood pressures were measured on the right arm and using an automated blood
pressure monitor (BPM 300-BpTRU: Vital Signs Monitor) after a 10-minute rest in the
sitting position. Measurement of blood pressure was computed as a mean of three readings.
Perceived Adherence to the MedDiet
At the end of the nutritional intervention (t = 12 weeks), men and women were invited to
rate their perception of adherence to the MedDiet principles according to a visual analog
scale (VAS) (ranging from 0 to 150 mm). Accordingly, the following question was asked:
“In your opinion, to what extent your current dietary intakes meet the MedDiet principles?”
(Not at all to perfectly). The distance between 0 mm and the vertical mark drawn on the
150 mm horizontal line was then measured with a ruler and corresponded to the perceived
level of adherence to the MedDiet (adapted from Dansinger et al. (26)).
Results are first presented in descriptive tables with pre-intervention (t = 0) and postintervention (t = 12 weeks) mean values (95% CI) according to men and women (Tables 2
and 4). Then, results are reported as changes within men and within women (delta values)
calculated as post-nutritional intervention minus pre-nutritional intervention values and as
percentage of change from baseline value (with P value), and two columns with the
difference between men and women and the difference between men and women adjusted
for the baseline value of the response variable, as means (95% CI) (Tables 3 and 5).
Differences between men and women in dietary intakes, anthropometric and metabolic
variables were assessed using an analysis of covariance (GLM procedure) on delta values.
The least squares means (LSMEANS) of the GLM procedure, which can be defined as a
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linear combination (sum) of the estimated effects, e.g. means, from a linear model and
based on the model used, allowed determining significant changes in outcomes over time in
men and women. The main model of the GLM procedure included gender only, but
additional analyses included gender, baseline value of the response variable and gender by
baseline value interaction in the model. The interaction was removed from the model when
it did not reach statistical significance. Student’s t-test was used to compare macronutrient
intakes as well as anthropometric and metabolic variables of men and women before the
beginning of the nutritional intervention program and allowed comparisons of the perceived
adherence to the MedDiet between men and women. The Chi-Square test was performed to
compare the frequencies of categorical data, i.e. attrition rate and attendance rate to
intervention sessions, between men and women. Since three different dietitians were in
charge of providing the intervention, the intervener effect was tested using an analysis of
variance with the GLM procedure. For variables not normally distributed, a transformation
was performed but these variables are presented as raw data in the tables. In order to
determine sample size, we considered a difference of 35% in the change in Medscore as
being clinically significant, based on results of a previous study from our group
(21)
.
Therefore a final sample size of 45 men and 45 women was needed to detect a difference of
35% in the change in Medscore between men and women with a power of 0·80 and alpha
of 0·05, considering that standard deviation corresponds to 55% of the mean of the change
in Medscore. The probability level for significance used for the interpretation of all
statistical analyses was set at a  level of P  0·05. All analyses were performed using SAS
statistical software (version 9.2, SAS Institute Inc., Cary, NC).
RESULTS
Table 1 shows characteristics of men and women in terms of their age, anthropometric
variables and metabolic profile. Men and women included in our study were about the same
age, but men had higher BMI, waist circumference, total-C to HDL-C ratio and
triacylglycerol levels than women, whereas women had a higher percentage of body fat and
HDL-C levels than men.
104
Overall, attrition rate was similar in men and women (10·9% and 13·6% respectively, P =
0·66), and except for higher LDL-C levels in completers, no significant differences were
observed in baseline characteristics of participants who dropped out versus the ones who
completed the 12-week nutritional intervention. Among completers, no differences between
men and women were observed for the attendance rate to the whole intervention (8·9 (SD
2·0) sessions in men and 9·0 (SD 1·8) in women, out of a maximum of 10 sessions) nor for
each component taken separately i.e. attendance to group meetings (2·3 (SD 0·8) in men
and 2·5 (SD 0·7) in women, out of a maximum of 3 meetings), individual counselling
sessions (2·8 (SD 0·6) in men and 2·8 (SD 0·5) in women, out of a maximum of 3 sessions)
and follow-up phone calls (3·7 (SD 0·9) in men and 3·7 (SD 0·8) in women, out of a
maximum of 4 follow-up phone calls). Moreover, a significant difference in attendance rate
between the different group meetings was observed (P  0·0001), with the higher
participation rate found at the lecture on traditional Mediterranean principles (group
meeting 1) and the lower rate found at the potluck dinner (group meeting 3). Briefly, 95·2,
82·5 and 57·1% of men (P  0·0001) and 98·3, 83·1 and 71·2% of women (P  0·0001)
attended group meeting 1, 2 and 3, respectively. Similarly, significant differences in
attendance rate between the different individual counselling sessions and also between the
different follow-up phone calls were observed (P = 0·002 and P = 0·006, respectively),
with a progressive decrease over time in the participation rate. The change in Medscore was
not influenced by the dietitian in charge of the intervention as indicated by the analysis of
variance (F = 0·36; P = 0·70).
Table 2 presents nutritional intakes as well as the Medscore and its components at baseline
and at the end of the intervention, and Table 3 presents changes in these variables in
response to the 12-week nutritional intervention program, in men and women separately.
Significant differences between men and women were found for changes in energy density,
percentage of energy intake provided by lipids, saturated and trans fatty acids and total
dietary fiber intake. Indeed, men significantly decreased more their energy density, had a
greater increase in total dietary fiber intake, and greater decreases in percentage of energy
intake from lipids, saturated and trans fatty acids than women, in response to the
intervention. Moreover, both men and women significantly increased the percentage of
105
energy intake provided by polyunsaturated fatty acids, although no difference was observed
between them. Also, a significant decrease in energy intake was observed in men only in
response to the intervention. When statistical analyses were adjusted for the baseline value
of the response variable, similar results were obtained for the percentage of energy intake
provided by saturated fatty acids and total dietary fiber intake whereas differences between
men and women were no longer significant for energy density, percentage of energy intake
provided by lipids and trans fatty acids.
As for the Medscore, both men and women showed increases in response to the
intervention but without significant differences among them. With regards to Medscore
components, significant differences between men and women were observed for red and
processed meat and fruit intakes. The decrease in red and processed meat and the increase
in fruit consumption were more pronounced in men than in women. In addition, intakes of
legumes, nuts and seeds, whole grain products and fish and seafood increased while the
intake of refined grain products decreased in both men and women without significant
differences between them. Moreover, a significant increase in vegetable intake was only
observed in men whereas a significant increase in olive oil and olive consumption was only
observed in women, in response to the intervention. After statistical adjustment for the
baseline value of the response variable, differences between men and women observed for
changes in red and processed meat and fruit intakes were no longer significant. Moreover,
significant differences between men and women were observed for legumes, nuts and seeds
and whole grain products intakes once adjusted for the baseline value, with greater
increases observed for theses variables in men than in women.
At the end of the nutritional intervention, the perceived level of adherence to the MedDiet,
as determined by VAS, was not different between men and women (99·8 (SD 24·2) mm in
men and 100·1 (SD 25·3) mm in women; T = 0·07; P = 0·94). A significant and positive
association in both men (r = 0·33; P = 0·01) and women (r = 0·28; P = 0·05) was observed
between perceived level of adherence to the MedDiet and the actual Medscore calculated
after the 12-week nutritional intervention.
106
Table 4 presents anthropometric and metabolic values at baseline and at the end of the
intervention, and Table 5 presents changes in anthropometric and metabolic variables in
response to the 12-week nutritional intervention program, in men and women separately.
As shown in Table 5, no significant differences between men and women were observed
for anthropometric changes, in response to the nutritional intervention. However,
significant decreases were observed for BMI and waist circumference in both men and
women. Also, despite the trend for women to decrease their body weight, only men
significantly decreased their body weight and percentage of body fat in response to the
nutritional intervention. As for metabolic changes, significant differences between men and
women were found for total-C to HDL-C and triacylglycerols to HDL-C ratios, with greater
decreases observed for these variables in men than in women. In addition, results showed
significant changes in HDL-C (increase) and in triacylglycerol levels and diastolic blood
pressure (decreases) in response to the intervention, but only in men. Moreover, differences
between men and women observed in total-C to HDL-C and triacylglycerols to HDL-C
ratios became non significant after adjustment for the baseline value.
DISCUSSION
The aim of our study was to determine differences between men and women in dietary,
anthropometric and metabolic changes, in response to a 12-week nutritional intervention
program promoting the adoption of the MedDiet, and based on the SDT. Results showed
that our nutritional intervention led to improvements in dietary, anthropometric and
metabolic profile, that were generally more pronounced in men than in women.
Our results indicate that both men and women increased their level of adherence to the
MedDiet (Medscore) in response to the 12-week nutritional intervention and therefore both
men and women improved general quality of their diet. This improvement in the level of
adherence to the MedDiet also indicates that our nutritional intervention program based on
the SDT appears to be appropriate for both men and women. Moreover, the significant
association found in both men and women between perceived level of adherence to the
107
MedDiet and the actual Medscore calculated suggests that men and women had a similar
understanding of the intervention and also the capability to assess the quality of their diet
accurately after the end of the 12-week nutritional intervention, which represents relevant
information in a context of nutritional education.
Although men and women improved their dietary intakes as shown by the increase in the
Medscore, differences between men and women were observed when examining individual
components of the Medscore, which were concordant with changes observed in nutritional
intakes in response to the intervention. Indeed, the more pronounced changes observed in
men in some food groups, e.g., by greater decrease in red and processed meat and greater
increase in fruit consumption were consistent with some differences between men and
women observed in nutrient intakes such as the greater decreases in energy density,
percentage of energy provided by lipids, saturated and trans fatty acids, and the greater
increase in fiber intake in men than in women. Moreover, the significant decrease in energy
density in men was concordant with the decrease in daily energy intake, as previous studies
have reported that decreasing energy density of the diet leads to a spontaneous decrease in
energy intake
(27)
. Similarly to our findings, results from a nutritional intervention, which
promoted the traditional MedDiet over a period of 12 months among a Spanish population,
reported a greater success in men than in women when considering the level of adherence
to the MedDiet
(12)
. On the other hand, our results are different from other studies
(13, 28)
reporting greater dietary changes in women than in men. Several differences in the
intervention design can explain that differences between men and women regarding
changes in dietary intakes observed in response to our nutritional intervention program
differ, for example, from the study of Bemelmans et al. (13). First, our intervention included
group but also individual counselling sessions to individualise dietary objectives and
strategies adopted and to support men and women to overcome barriers in the adoption of
the MedDiet, whereas only group sessions were provided to men and women in the study
of Bemelmans et al. (13). Second, our nutritional intervention aimed at promoting autonomy
and competence in men and women towards the adoption of the MedDiet. Indeed, we did
so by supporting them in their dietary changes and strategies to achieve these changes and
by promoting the development of their skills and knowledge related to nutrition, which
108
contrasts with specific nutritional guidelines and daily intake explained at the beginning of
the intervention in the study of Bemelmans et al.
(13)
. It can be argued that providing more
details about dietary guidelines may reduce the possibility for autonomy and that a more
passive role of subjects in a nutritional intervention could explain divergence in results
obtained among studies. Globally, direct comparison of our results to those from the
literature remains difficult because of major differences in the intervention design and
statistical analyses among studies.
Some baseline characteristics in men and women may have influenced the magnitude of
dietary changes observed in response to our nutritional intervention. Accordingly, healthier
diet at baseline of a dietary intervention has been previously reported to decrease the
likelihood of observing significant dietary changes
(12)
. The fact that women in our study
had globally dietary intakes of higher quality at baseline and which tended to be closer to
the traditional MedDiet pattern than those of men could thus possibly explain, at least
partially, differences between men and women observed in dietary changes. In the context
of our nutritional intervention, it can be hypothesized that because men’ dietary intakes at
baseline were generally further away from MedDiet principles, they could possibly identify
more easily changes that could be made and modify their eating habits, especially in the
context of individual counselling sessions where specific dietary objectives were settled.
Accordingly, the fact that many differences between men and women observed were no
longer significant once dietary changes were adjusted for the baseline value of the response
variable brings support to this hypothesis. Our results underline the importance of
considering the characterization of the dietary profile of men and women before the
beginning of a nutritional intervention to properly respond to the clients’ needs and
maximize potential improvements in dietary intakes during the intervention. However,
because some differences between men and women in dietary changes were significant
once adjusted for the baseline value of the response variable, it is suggested that differences
between men and women regarding other factors than baseline dietary intakes, such as
attitudes and beliefs towards health and nutrition, might have influenced their response to
the nutritional intervention. Our hypothesis is in agreement with a previous study
(29)
reporting that health attitudes and beliefs are relevant predictors of adherence to health
109
recommendations. The use of mixed methods in which qualitative and quantitative data are
combined would therefore warrant to be considered in the future to get more specific
information about such factors in men and women.
Although our nutritional intervention promoted healthy dietary changes with no focus on
body weight, both men and women showed improvements in their anthropometric profile
with significant decreases in BMI and waist circumference, in response to the 12-week
nutritional intervention. Our results are concordant with previous studies, which found that
a higher adherence to the MedDiet was associated with lower prevalence of overweight or
obesity
(30, 31)
. The MedDiet is recognized to be highly satiating
(31, 32)
and our results
suggest that dietary changes led to increased satiety. More specifically, increases in
legumes, nuts and seeds and whole grain products intakes reported in both men and women
possibly contributed to a decrease in energy density through increased water content and
fiber intake
(33)
. Moreover, the decrease in red and processed meat intake can have led to
replacement of animal proteins by vegetable proteins sources such as legumes, nuts and
seeds, which contain satiating components such as proteins and fibers (34, 35).
As for metabolic profile, our results showed more pronounced changes in metabolic
variables in men than in women and these can possibly be explained by greater dietary
changes observed in men, in response to the nutritional intervention. As suggested by
Estruch et al.
(1)
, potential synergy among nutrient-rich foods included in the MedDiet
might foster favourable changes in some pathways of cardiovascular risks. It is also
possible that some sex-related characteristics such as the level of sex hormones may
interact with the complex synergistic effect between food components, resulting in smaller
beneficial impact of the MedDiet in women than in men. In support of this, we recently
reported significant improvements in insulin homeostasis in men only, in response to an
isoenergetic controlled experimental diet based on the traditional MedDiet where all foods
and drinks were provided to the participants
(7)
. However, the absence of differences
between men and women in metabolic changes once statistical adjustment was performed
for the baseline value of the response variable underlines the importance of the metabolic
status at the beginning of a nutritional intervention program. Indeed, results related to
110
metabolic changes suggest that an individual with more deteriorated metabolic variables
before the beginning of a nutritional intervention could show greater health improvements
in response to the intervention, which is concordant with the fact than men in our study had
a more deteriorated metabolic profile at baseline and improved more in response to the
intervention than women.
We acknowledge that our results cannot be extrapolate to the whole population because we
recruited men and women presenting risk factors for CVD and who had dietary intakes
closer to recommendations of the Canada’s Food Guide recommendations than the general
adult population in Canada (36). Moreover, although anthropometric and metabolic variables
were measured, dietary intakes were self-reported. Therefore, the risk of misreporting
dietary intakes cannot be excluded. Our study has also important strengths such as the fact
that analyses were conducted distinctively in men and women according to dietary intakes,
anthropometric and metabolic profile in the context of a nutritional intervention program.
Also, our nutritional intervention based on the SDT appears to be acceptable for both men
and women as similar attrition and attendance rate to the intervention as well as to its
specific components (i.e. group meetings, individual sessions, follow-up phone calls) was
observed among them. Although attrition rate found in our study was similar to those
reported in the literature among nutritional interventions based on a motivational
interviewing approach
(37)
, reasons for not attending to some sessions remain difficult to
identify and might differ among men and women. It remains essential to consider the
clinical implication related to attendance rate when developing a nutritional intervention.
Indeed, the lack of flexibility in the schedule related to group meetings attendance must be
considered in the development of interventions as it may require efforts for some people to
attend pre-scheduled meetings and this might progressively generate fatigue with time. It is
also possible that active participation in practical activities, for example the cooking lesson,
may be perceived as requiring too much effort for some individuals. Nevertheless, our
study underlines the potential of improvement in adherence to the MedDiet among a nonMediterranean population, more specifically in the context of an intervention during which
men and women chose their own dietary objectives (i.e. based on their personal interest and
motivations). In addition, our results bring information about differences between men and
111
women in potential health benefits obtained following a 12-week nutritional intervention
program promoting the MedDiet, and thus support the relevance to consider gender in the
development of nutritional intervention programs aimed at preventing chronic diseases.
In conclusion, our results suggest that the nutritional intervention program promoting the
adoption of the MedDiet and based on the SDT led to greater improvements in dietary
intakes in men than in women, which appear to have contributed to beneficial
anthropometric and metabolic changes, more particularly in men. However, our results also
suggest that the more deteriorated metabolic profile found in men at baseline appears to
explain to a large extent the fact that the improvements in CVD risk factors were more
pronounced in men than in women in response to the intervention.
FINANCIAL SUPPORT
AUTHORSHIP
interpretation of data and drafted the manuscript; A-M.H. and M-M.R. contributed to the
112
acquisition of data; C.B. contributed to the conception and design of the study as well as to
the interpretation of data; L.C. and S.D. contributed to the conception and design of the
study; S.L. (corresponding author) was responsible for the conception and design of the
study and contributed to the interpretation of data. All of the authors have read and
approved the final version of the manuscript submitted for publication.
113
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WKHHQGRIWKHLQWHUYHQWLRQWLPH ZHHNV
Table 1. Baseline characteristics of men and women
Men (n=64)
Mean
SD
41·0
7·9
30·8
4·4
26·7
4·5
106·1
10·2
3·6
0·7
1·1
0·2
5·1
1·0
1·9
0·9
5·3
0·5
Women (n=59)
Mean
SD
41·8
6·7
29·6*
6·0
39·2*
6·2
95·8*
11·5
3·6
0·7
1·4*
0·3
4·2*
0·9
1·5*
0·6
5·2
0·7
Age (years)
Body fat (%) ¥
LDL-C (mmol/l)
HDL-C (mmol/l)
Total-C/HDL-C ratio
Triacylglycerols (mmol/l)
Fasting glucose (mmol/l)
SD, Standard deviation.
* Mean values were significantly different between men and women (P ≤ 0·05, Student's
t-test).
¥ n = 52 for men and n = 48 for women because of missing values.
For metabolic variables n = 63 for men and n = 58 for women because of missing values.
120
Table 2. Dietary intakes, Medscore and food group intakes at baseline and after the 12-week nutritional intervention program (Mean
values and 95% confidence intervals)
Men
Variables
Dietary intakes
Energy intake (kJ)
Energy density (kJ/g) £
% Carbohydrates
Total dietary fibers (g)
% Proteins
% Lipids
% MUFA
% PUFA
% SFA
% Trans
% Alcohol
Mediterranean score and food groups
Medscore (arbitrary units)
Olives (portions/d)
Rapeseed oil (portions/d)
Vegetables (portions/d)
Vegetable juices (portions/d)
Legumes, nuts and seeds (portions/d)
Whole grain products (portions/d)
Refined grain products (portions/d)
Milk and dairy products (portions/d)
T=0
(n=64)
95% CI
Women
T=12
(n=57)
95% CI
T=0
(n=59)
95% CI
(n=51)
T=12
95% CI
12 824
5·52
42·2
27·2
18·3
36·8
15·5
6·2
12·2
1·4
2·7
11887, 13761
5·27, 5·77
40·9, 43·5
24·8, 29·5
17·7, 19·0
35·6, 38·0
14·8, 16·2
5·9, 6·6
11·5, 12·9
1·3, 1·5
2·1, 3·3
11 581
5·06
44·1
32·8
18·4
34·6
15·1
6·8
10·1
1·1
2·9
10791, 12372
4·81, 5·31
42·5, 45·6
30·0, 35·7
17·6, 19·1
33·2, 36·0
14·3, 15·9
6·4, 7·2
9·4, 10·7
1·0, 1·2
2·2, 3·6
10 280*
5·06*
44·5*
25·6
17·8
35·1*
14·6¶
5·9
11·8
1·3*
2·7
9657, 10904
4·90, 5·23
43·0, 46·0
23·9, 27·2
17·0, 18·5
33·9, 36·2
13·9, 15·3
5·5, 6·2
11·4, 12·2
1·2, 1·3
2·1, 3·2
9770
4·98
44·8
28·1
17·9
34·6
15·1
6·3
10·5
1·1
2·7
9150, 10389
4·77, 5·19
43·2, 46·3
26·0, 30·2
17·1, 18·7
33·1, 36·1
14·1, 16·0
5·9, 6·7
10·0, 11·1
1·0, 1·2
2·1, 3·3
22·7
1·1
0·2
3·8
0·3
1·3
3·2
3·3
3·1
21·6, 23·8
0·7, 1·4
0·1, 0·3
3·4, 4·3
0·2, 0·4
0·9, 1·6
2·8, 3·6
2·8, 3·7
2·6, 3·6
27·6
1·5
0·2
4·3
0·3
1·9
3·7
1·9
2·8
26·4, 28·9
1·2, 1·8
0·1, 0·3
3·8, 4·9
0·2, 0·4
1·6, 2·3
3·3, 4·1
1·6, 2·2
2·3, 3·3
24·1¶
1·0
0·2
4·3
0·3
0·8*
2·3*
2·7¶
2·6¶
23·1, 25·0
0·7, 1·2
0·1, 0·2
3·9, 4·6
0·2, 0·4
0·7, 1·0
1·9, 2·8
2·3, 3·1
2·3, 2·9
27·2
1·6
0·2
4·3
0·2
1·2
2·9
1·9
2·4
25·8, 28·6
1·1, 2·1
0·1, 0·3
3·9, 4·8
0·1, 0·4
1·0, 1·4
2·5, 3·2
1·6, 2·3
2·1, 2·7
121
Table 2. Dietary intakes, Medscore and food group intakes at baseline and after the 12-week nutritional intervention program (continued)
Men
Variables
T=0
(n=64)
95% CI
Women
T=12
(n=57)
95% CI
T=0
(n=59)
95% CI
Fruits (portions/d)
1·7
1·4, 2·1
2·6
2·1, 3·2
2·5*
Fruit juices (portions/d)
1·5
1·1, 1·8
1·3
1·0, 1·6
1·1¶
Poultry (portions/d)
0·9
0·7, 1·1
0·8
0·6, 0·9
0·7*
Fish and seafood (portions/d)
0·6
0·5, 0·8
1·1
0·9, 1·3
0·5
Red meat/processed meat (portions/d)
1·7
1·4, 1·9
0·8
0·7, 0·9
1·1*
Eggs (portions/d)
0·5
0·4, 0·5
0·5
0·4, 0·6
0·3*
Sweets (portions/d)
2·0
0·8, 3·2
1·0
0·6, 1·5
1·3
* Mean value was significantly different from that for men at baseline (P ≤ 0·05, Student's t-test).
¶ Mean value was marginally significantly different from that for men at baseline (P ≤ 0·10, Student's t-test).
£ Including energy-containing foods and drinks drinks.
122
2·1, 2·8
0·8, 1·4
0·6, 0·8
0·4, 0·7
1·0, 1·3
0·3, 0·4
1·0, 1·7
(n=51)
T=12
95% CI
2·6
1·0
0·6
0·9
0·7
0·3
0·9
2·2, 3·0
0·7, 1·4
0·5, 0·7
0·7, 1·0
0·6, 0·8
0·2, 0·4
0·7, 1·2
Table 3. Changes in dietary intakes, Medscore and food group intakes in response to the 12-week nutritional intervention program
Variables
Δ 0-12
weeks
Dietary intakes
Energy intake (kJ)
-1151
Energy density (kJ/g) £ *
-0·54
% Carbohydrates
2·2
5·9
% Proteins
0·06
% Lipids
-2·5
% MUFA
-0·5
% PUFA
0·5
% SFA
-2·2
% Trans *
-0·3
% Alcohol
0·3
4·9
Olives (portions/d)
0·4
Rapeseed oil (portions/d) * §
0·02
Vegetables (portions/d)
0·6
Vegetable juices (portions/d)
0·02
Legumes, nuts and seeds
0·6
(portions/d)
Men
Women
(n=57)
%
Change
Men vs. women
differences
Men vs. women
differences
adjusted for
baseline value
P
Mean (95% CI)
Mean (95% CI)
P
Δ 0-12
weeks
(n=51)
%
Change
-9·0
-9·8
5·2
21·7
0·3
-6·8
-3·2
8·1
-18·0
-21·4
11·1
0·004
< 0·0001
0·008
< 0·0001
0·88
0·001
0·24
0·04
< 0·0001
< 0·0001
0·33
-607
-0·08
-0·05
2·6
0·2
-0·3
0·5
0·5
-1·2
-0·1
0·1
-5·9
-1·6
-0·1
10·2
1·1
-0·9
3·4
8·5
-10·2
-7·7
3·7
0·14
0·58
0·96
0·02
0·63
0·72
0·36
0·04
0·0002
0·03
0·61
-544 (-1660, 573)
-0·1 (-0·2, -0·02) †
2·2 (-0·1, 4·6)
3·4 (0·4, 6·3) †
-0·1 (-1·3, 1·0)
-2·2 (-4·4, -0·02) †
-1·0 (-2·4, 0·4)
-0·04 (-0·7, 0·7)
-1·0 (-1·9, -0·2) †
-0·2 (-0·4, -0·02) †
0·1 (-0·6, 0·9)
821 (-123, 1765)
-0·03 (-0·1, 0·04)
0·5 (-1·6, 2·6)
3·8 (0·9, 6·6)
0·2 (-0·8, 1·2)
-0·8 (-2·8, 1·1)
-0·3 (-1·5, 0·9)
0·3 (-0·2, 0·9)
-0·8 (-1·5, -0·05)
-0·09 (-0·2, 0·07)
0·1 (-0·6, 0·8)
21·6
36·4
10·0
15·8
6·7
< 0·0001
0·08
0·75
0·02
0·70
3·2
0·6
0·04
0·06
-0·02
13·3
60·0
20·0
1·4
-6·7
< 0·0001
0·02
0·54
0·85
0·78
1·7 (-0·3, 3·7)
-0·2 (-0·8, 0·5)
-0·02 (-0·2, 0·1)
0·6 (-0·2, 1·4)
0·04 (-0·1, 0·2)
0·8 (-0·9, 2·6)
-0·1 (-0·6, 0·4)
0·006 (-0·1, 0·1)
0·2 (-0·4, 0·9)
0·05 (-0·1, 0·2)
46·2
0·0001
0·4
50·0
0·03
0·3 (-0·2, 0·7)
0·6 (0·2, 1·0)
123
Table 3. Changes in dietary intakes, Medscore and food group intakes in response to the 12-week nutritional intervention program
(continued)
Men vs. women
Men vs.
differences
Men
Women
women
adjusted for
differences
baseline value
(n=57)
(n=51)
Δ 0-12
%
Δ 0-12
%
Variables
P
P
Mean (95% CI) Mean (95% CI)
weeks Change
weeks Change
Whole grain products (portions/d)
0·5
15·6
0·03
0·5
21·7
0·02
-0·06 (-0·6, 0·5) 0·5 (0·01, 1·0)
Refined grain products (portions/d) * §
-1·3
-39·4 < 0·0001 -0·8
-29·6
0·0009
-0·5 (-1·1, 0·2)
-0·2 (-0·6, 0·3)
Milk and dairy products (portions/d)
-0·2
-6·5
0·39
-0·1
-3·8
0·54
-0·05 (-0·7, 0·6)
0·2 (-0·3, 0·7)
Fruits (portions/d)
1·0
58·8
0·0001
0·09
3·6
0·74
0·9 (0·2, 1·6) †
0·4 (-0·3, 1·1)
Fruit juices (portions/d)
-0·2
-13·3
0·29
-0·1
-9·1
0·50
-0·05 (-0·5, 0·4) 0·08 (-0·3, 0·5)
Poultry (portions/d)
-0·08
-8·9
0·27
-0·1
-14·5
0·20
0·02 (-0·2, 0·2) 0·1 (-0·04, 0·3)
Fish and seafood (portions/d)
0·4
66·7 < 0·0001
0·3
60·0
0·0004
0·1 (-0·2, 0·3)
0·1 (-0·1, 0·4)
Red meat/processed meat (portions/d)
-0·9
-52·9 < 0·0001 -0·5
-45·5
< 0·0001 -0·4 (-0·7, -0·1) † -0·03 (-0·2, 0·2)
Eggs (portions/d)
-0·004 -0·8
0·93
-0·03
-10·0
0·52
0·03 (-0·1, 0·2) 0·1 (-0·01, 0·2)
Sweets (portions/d) * §
-1·0
-50·0
0·05
-0·4
-30·8
0·46
-0·6 (-2·1, 0·9) -0·03 (-0·6, 0·5)
Δ 0-12 weeks, Change following the 12-week nutritional intervention program.
* P ≤ 0·05, Significant interaction between gender and baseline value.
† P ≤ 0·05, Significant differences in men vs. women between 0-12 weeks without adjustment for the baseline value.
£ Including energy-containing foods and drinks drinks.
§ Analysis was performed on transformed values.
124
Table 4. Anthropometric and metabolic variables at baseline (time = 0) and after the 12-week nutritional intervention program
(time = 12)* (Mean values and 95% confidence intervals)
Men
Variables
T=0
(n=64)
95% CI
(n=57)
T=12
95% CI
Women
(n=59)
T=0
95% CI
(n=51)
T=12
95% CI
Body weight (kg)
96·6
92·7, 100,5
95·2
91·4, 99·0
77·9
73·5, 82·2
77·2
72·4, 82·0
30·8
29·7, 31·9
30·2
29·2, 31·3
29·6
28·0, 31·2
29·4
27·7, 31·1
Body fat (%) †
26·7
25·4, 27·9
25·6
24·2, 26·9
39·2
37·4, 41·0
39·2
37·1, 41·2
106·1 103·6, 108·7 104·2 101·7, 106·7
95·8
92·9, 98·8
94·5
91·0, 98·1
HDL-C (mmol/l) ‡
1·1
1·1, 1·2
1·2
1·1, 1·3
1·4
1·4, 1·5
1·4
1·4, 1·5
LDL-C (mmol/l) ‡
3·6
3·5, 3·8
3·7
3·5, 3·9
3·6
3·5, 3·8
3·6
3·4, 3·8
Apo-B (g/l) ‡
1·2
1·1, 1·2
1·2
1·1, 1·2
1·1
1·1, 1·2
1·1
1·1, 1·2
Total-C/HDL-C ratio ‡
5·1
4·8, 5·3
4·9
4·6, 5·1
4·2
3·9, 4·4
4·1
3·8, 4·3
Triacylglycerols (mmol/l) ‡
1·9
1·7, 2·1
1·6
1·4, 1·8
1·5
1·3, 1·6
1·4
1·2, 1·5
Triacylglycerols/HDL-C ratio ‡
1·8
1·5, 2·0
1·4
1·2, 1·6
1·1
1·0, 1·2
1·0
0·9, 1·1
Systolic blood pressure (mm Hg) ‡
119·8 116·1, 123·4 119·3 116·5, 122·1 109·2 106·3, 112·1 109·5 106·2, 112·8
Diastolic blood pressure (mm Hg) ‡
75·6
73·2, 78·0
72·4
70·2, 74·7
70·8
68·7, 72·8
68·9
66·6, 71·2
Fasting glucose (mmol/l) ‡
5·3
5·1, 5·4
5·3
5·2, 5·4
5·2
5·0, 5·3
5·2
5·0, 5·4
Fasting insulin (pmol/l) ‡
100·5
89·1, 111·8
98·9 87·2, 110·7
88·5
76·6, 100·5 88·2
76·9, 99·5
HDL-C, HDL-Cholesterol; LDL-C, LDL-Cholesterol; total-C, total cholesterol.
* All anthropometric and metabolic variables were significantly different between men and women at baseline (time = 0), except for
LDL-C, Apo-B, systolic and diastolic blood pressure, fasting glucose and insulin (P ≤ 0·05).
† Men (n = 52) and women (n = 48) because of missing values.
‡ Metabolic variables men (n = 63) and women (n = 58) because of missing values.
125
Table 5. Changes in anthropometric and metabolic variables in response to the 12-week nutritional intervention program
Men
Women
Men vs. women
differences
Men vs. women
differences adjusted
for baseline value
(n=57)
(n=51)
Δ 0-12
%
Δ 0-12
%
Variables
P
P
Mean (95% CI)
Mean (95% CI)
weeks
Change
weeks Change
Body weight (kg)
-1·0
-1·0
0·0003
-0·6
-0·8
0·06
-0·5 (-1·3, 0·3)
-0·6 (-1·6, 0·3)
-0·3
-1·0
0·0004
-0·2
-0·7
0·03
-0·1 (-0·4, 0·1)
-0·1 (-0·4, 0·1)
Body fat (%) ¥
-0·7
-2·6
0·003
-0·2
-0·5
0·31
-0·4 (-1·0, 0·2)
-0·4 (-1·4, 0·6)
-1·3
-1·2
0·01
-1·1
-1·1
0·04
-0·2 (-1·7, 1·3)
0·02 (-1·7, 1·7)
HDL-C (mmol/l)
0·05
4·5
0·005
0·01
0·7
0·42 0·04 (-0·01, 0·08) 0·007 (-0·05, 0·06)
LDL-C (mmol/l)
-0·03
-0·8
0·62
-0·06
-1·7
0·43
0·02 (-0·2, 0·2)
0·05 (-0·1, 0·2)
Apo-B (g/l)
-0·02
-1·7
0·33
-0·01
-0·9
0·58 -0·007 (-0·05, 0·04) 0·002 (-0·04, 0·05)
Total-C/HDL-C ratio
-0·3
-5·9
< 0·0001 -0·1
-2·4
0·13 -0·2 (-0·4, -0·03) †
-0·08 (-0·3, 0·1)
Triacylglycerols (mmol/l) * §
-0·3
-15·8
0·0002
-0·09
-6·0
0·20
-0·2 (-0·4, 0·03)
0·01 (-0·2, 0·2)
Triacylglycerols/HDL-C ratio * §
-0·3
-16·7 < 0·0001 -0·08
-7·3
0·26 -0·2 (-0·4, -0·04) †
0·03 (-0·1, 0·2)
Systolic blood pressure (mm Hg)
1·0
0·8
0·41
0·4
0·4
0·74
0·6 (-3·0, 4·2)
3·9 (0·5, 7·4)
Diastolic blood pressure (mm Hg)
-2·4
-3·2
0·01
-1·6
-2·3
0·10
-0·8 (-3·3, 1·8)
0·6 (-1·9, 3·1)
Fasting glucose (mmol/l) * §
0·04
0·8
0·56
0·04
0·8
0·50 -0·007 (-0·2, 0·2)
0·02 (-0·1, 0·2)
Fasting insulin (pmol/l)
-1·6
-1·6
0·61
0·4
0·5
0·91
-2·0 (-11·2, 7·1)
0·3 (-8·3, 8·8)
Δ 0-12 weeks, Change following the 12-week nutritional intervention program; HDL-C, HDL-Cholesterol; LDL-C, LDL-Cholesterol;
total-C, total cholesterol.
* P ≤ 0·05, Significant interaction between gender and baseline value.
† P ≤ 0·05, Significant differences in men vs. women between 0-12 weeks without adjustment for the baseline value.
§ Analysis was performed on transformed values.
126
CHAPITRE 5 :
Différences relatives au genre dans les effets à long
terme d’un programme d’intervention nutritionnelle
visant l’adoption de l’alimentation méditerranéenne :
changements dans les apports et comportements
alimentaires, ainsi que dans les variables
anthropométriques et métaboliques
Vicky Leblanc, Catherine Bégin, Anne-Marie Hudon, Marie-Michelle Royer, Louise
Corneau, Sylvie Dodin, Simone Lemieux
Nutrition Journal, 2014 Nov 22;13 :107.
127
Gender differences in the long-term effects of a nutritional intervention program
promoting the Mediterranean diet: Changes in dietary intakes, eating behaviors,
anthropometric and metabolic variables
Vicky Leblanc1, Catherine Bégin2, Anne-Marie Hudon1, Marie-Michelle Royer1, Louise
Corneau1, Sylvie Dodin1,3, and Simone Lemieux1.
1
2
3
Department of Obstetric and Gynaecology, Laval University, Pavillon Ferdinand-
Vandry, 1050 Medicine Avenue, Québec, Canada, G1V 0A6
2440 Hochelaga Blvd
Phone: (418) 656-2131 ext.: 3637
Fax: (418) 656-5877
Keywords : Gender differences, Mediterranean diet, Cardiovascular risk, long-term
dietary changes.
Abbreviations: MedDiet, Mediterranean diet; CVD, Cardiovascular diseases; SDT,
Self-Determination Theory; C, Cholesterol; FSH, Follicle-stimulating hormone;
Medscore, Mediterranean score; MI, Motivational interviewing; FFQ, Food frequency
questionnaire; BMI, Body mass index; TFEQ, Three-Factor Eating Questionnaire.
129
RÉSUMÉ
Cette étude visait à déterminer les différences de genre dans les effets d’une
intervention nutritionnelle visant l’adoption de l’alimentation méditerranéenne et basée
sur la théorie de l’autodétermination sur les apports et comportements alimentaires,
ainsi que sur les variables anthropométriques et métaboliques à long terme. Soixantequatre hommes et 59 femmes préménopausées à risque de maladies cardiovasculaires
ont pris part à l’intervention de 12 semaines. Les apports alimentaires ont été évalués
via un questionnaire de fréquence, à partir duquel un score méditerranéen a été calculé.
Le Three-Factor Eating Questionnaire a permis d’évaluer les comportements
alimentaires. Aucune différence de genre n’a été notée dans les changements du score
méditerranéen à long terme. Les hommes ont diminué leur consommation de viandes
rouges et augmenté leur consommation de fruits entiers de façon plus importante que les
femmes. Une diminution plus prononcée de la susceptibilité habituelle à la désinhibition
a été observée chez les hommes. Une interaction genre par temps a été notée pour la
circonférence de la taille alors que des changements métaboliques (ratio C-total sur CHDL, triglycérides) plus importants ont été mesurés chez les hommes. Ces résultats
suggèrent que l’intervention a engendré des bienfaits plus prononcés à long terme dans
les apports alimentaires et sur le profil métabolique des hommes comparativement aux
femmes.
131
ABSTRACT
Long-term adherence to principles of the Mediterranean diet (MedDiet) following a
nutritional intervention promoting the Mediterranean food pattern in Canadian men and
women is not known. Moreover, gender differences in dietary and metabolic profile in
such an intervention context has never been addressed. Objective was to determine
gender differences in long-term effects of a 12-week nutritional intervention program
promoting the adoption of the MedDiet and based on the Self-Determination Theory
(SDT) on dietary intakes, eating behaviors, anthropometric and metabolic variables, in
men and women presenting cardiovascular risk factors. Sixty-four men and 59
premenopausal women were recruited. The 12-week nutritional program used a
motivational interviewing approach and included individual and group sessions. A food
frequency questionnaire was administered to evaluate dietary intakes from which a
Mediterranean score (Medscore) was derived and the Three-Factor Eating
Questionnaire allowed assessment of eating behaviors. Measurements were performed
at baseline and after the 12-week nutritional intervention, and then at 3 and 6-month
post intervention. No gender difference was observed in changes in the Medscore
during the nutritional intervention and follow-up. However, the Medscore returned
towards baseline values during follow-up in men and women (P < 0.0001). Men
reported larger decreases in red and processed meat and larger increases in whole fruit
intakes than women (for both, P = 0.03). Men showed a greater decrease in habitual
susceptibility to disinhibition than women (P =0.03 and P =0.04, respectively). A
gender by time interaction was found for waist circumference, i.e. men had lower waist
circumference at the end of the intervention as well as at follow-up than at baseline
while women’s waist circumference decreased in response to the intervention only (P =
0.05). As for metabolic variables, changes observed in total-cholesterol (C) to HDL-C
ratio, triglyceride levels and triglycerides to HDL-C ratio were more pronounced in men
than in women after the intervention as well as at follow-up (P ≤ 0.01). Our results
indicate that the 12-week nutritional intervention based on the SDT leads to more
pronounced beneficial changes in long-term dietary intakes in men than in women and
to greater improvements in metabolic profile in men.
133
INTRODUCTION
Evidence of the benefits of the Mediterranean diet (MedDiet) on health is now well
established in the literature. Indeed, the MedDiet is recognized as one of the best models
of health food patterns providing protection against chronic diseases, such as
cardiovascular diseases (CVD) and cancer (1, 2). Accordingly, high level of adherence to
the MedDiet has been reported to be negatively associated with several cardiovascular
risk factors although heterogeneity related to demographic characteristics (i.e., country,
gender, socio-cultural status) has been observed (3).
Changing dietary habits represents a major challenge for many people
(4, 5)
. In this
regard, although adherence to the MedDiet is beneficial for CVD prevention
(5, 6)
,
previous studies reported difficulties regarding maintenance of the MedDiet principles
(5, 7)
. Evidence suggests favourable diet adherence outcomes in the context of different
intervention settings lasting over a 12-month period
(8)
and including sustained support
to individuals in the long term (e.g., information, individual or group sessions)
(9, 10)
.
These results therefore indicate the relevance of providing long-term support to
individuals. However, according to actual public health priorities in Canada
(11)
, long-
term nutritional support, which requires several professional and financial resources,
remains unrealistic to address CVD prevention at a population level. In this context,
nutritional interventions supporting autonomy and competency of individuals, in
agreement with the Self-Determination Theory (SDT) which emphasizes the importance
of motivation quality and self-determined forms of motivation towards behavior change
(12)
, are relevant.
Beyond intervention modalities, a variety of individual factors have been proposed to
influence the ability to maintain dietary changes. In fact, individual preferences in food
selection, preparation and consumption, variables related to socioeconomic and
education levels and lifestyle factors such as the degree of engagement in physical
activity have been suggested to play a role in the ability to maintain dietary changes in
the longer term
(13, 14)
. Moreover, previous studies have identified gender as a key
determinant of food choices. This can be explained by differences between men and
135
women in attitudes, beliefs and motivation towards healthy eating and also in their
awareness of diet and health issues
(15-17)
, which can possibly influence level of
adherence to dietary recommendations. In the context of the MedDiet, a higher success
in improving adherence to the MedDiet was observed among men than women after one
year of follow-up in the PREDIMED trial, which includes Spanish men and women
presenting high risk for CVD
(9)
. On the other hand, a study measuring the impact of a
MedDiet education program in hypercholesterolemic men and women from the
Netherlands showed that whereas women improved their dietary intakes in accordance
with the education program and significantly decreased their total-cholesterol (C) levels,
no such change was observed in men
(5)
. These differences between men and women
suggest that the process of sustaining dietary changes following a nutritional
intervention promoting the adoption of the MedDiet could be influenced by gender,
whether or not individuals come from Mediterranean regions. The feasibility of
adopting and maintaining the MedDiet has been reported in Canadian women (18), but no
data are available for Canadian men.
Evidence also indicates that the impact of adhering to dietary recommendations on
anthropometric and metabolic profiles can be modulated by sex and gender differences.
Indeed, metabolic changes in response to modification in dietary intakes can be
explained in part by sex differences, which essentially refer to biological and
physiological characteristics that distinguish males from females
(19)
, such as sex
hormones. Accordingly, a study published by our team showed improvement in insulin
homeostasis (i.e. insulin concentrations 2 hours after an oral administration of 75 g of
glucose) in men but not in women, in response to a 4-week MedDiet provided in the
context of a controlled study where all food and drinks were provided to participants in
isoenergetic conditions (20). On the other hand, gender differences previously reported in
eating behaviors (e.g., in dietary restraint and disinhibition levels)
through its association with dietary intakes
(22)
(21)
could influence,
, the level of adherence to dietary
recommendations in men and women and therefore could also influence long-term
changes in anthropometric and metabolic variables.
Overall, although the adoption of the MedDiet is recognized for its benefits on
metabolic profile, the long-term adherence to principles of the MedDiet following a
136
nutritional intervention program promoting the Mediterranean food pattern in Canadian
men and women is not known. Moreover, gender differences in dietary intakes, eating
behaviors, anthropometric variables and metabolic profile in such an intervention
context have never been addressed. The objective of this study was therefore to
determine gender differences in long-term effects of a 12-week nutritional intervention
program promoting the adoption of the MedDiet and based on the SDT on dietary
intakes, eating behaviors, anthropometric and metabolic variables, in Canadian men and
women presenting with risk factors for CVD.
METHODOLOGY
Participants
This study was conducted among a sample of 64 men and 59 premenopausal women
aged between 25 and 50 years old, and recruited through different media advertisements
in the Québec City Metropolitan area, Canada. In women, a follicle-stimulating
hormone (FSH) measurement was performed if needed (e.g., when women presented
periods irregularities) to confirm the premenopausal status (FSH <20 IU/l) (23). Men and
women had to present slightly elevated LDL-C concentrations (between 3.0 and 4.9
mmol/l)
(24)
or a total-C to HDL-C ratio ≥5.0, and at least one of the four following
criteria of the metabolic syndrome
(25)
: 1) triglyceride concentrations ≥1.7 mmol/l; 2)
fasting glycaemia between 6.1 et 6.9 mmol/l; 3) blood pressure concentrations ≥130/85
mm Hg; 4) waist circumference ≥80 cm in women and ≥94 cm in men
(26)
. Participants
also had to have a stable body weight (±2.5 kg) for a minimum of three months prior to
the beginning of the study and to be implicated in food purchases and/or preparation at
home. We excluded men and women who had cardiovascular events and who used
medication that could affect dependent variables under study. Pregnant women,
smokers, participants with an alcoholism history or with a high Mediterranean score
(Medscore >29, i.e. food pattern already highly concordant with the MedDiet)
(6)
were
also excluded. All subjects voluntarily agreed to participate in the research project and
written informed consent was obtained from all men and women prior to their
137
participation in the study. This study was approved by the Laval University Research
Ethics Committee.
Study Design
The 12-week nutritional program was based on the Self-Determination Theory (SDT)
and used a motivational interviewing (MI) approach. Briefly, the study was conducted
in five phases (from January 2010 to November 2012) and the nutritional intervention
included three group sessions (10–15 individuals / session), three individual sessions
and four follow-up phone calls with a registered dietitian (Figure 1). Three registered
dietitians were trained to provide a standardized intervention and participants always
met with the same dietitian during individual sessions. The first group session was a
lecture, provided by the same dietitian in all groups, and aimed at explaining principles
of the traditional MedDiet. The second group session was a Mediterranean cooking
lesson during which men and women had to cook a Mediterranean meal. Then, during
the third group session participants had to share a Mediterranean potluck dinner aimed
at discussing barriers in adopting dietary recommendations which occurred during the
intervention. Individual counselling took place at weeks one, five and 10 and lasted
between 45 minutes and one hour for each appointment. Individual follow-up phone
calls took place at weeks three, six, nine and 12, and lasted for about 20–30 minutes for
each phone call. The main objective of individual counselling and follow-up phone calls
was to assess dietary changes and to determine progressive personal goals aimed at
improving the adherence to MedDiet principles. Different tools congruent with the MI
approach were used during the individual sessions to formulate dietary objectives while
increasing self-determined motivation. Moreover, in accordance with the SDT (12), basic
psychological needs (i.e. autonomy, competence and relatedness) were supported during
the nutritional intervention via the MI approach in order to increase self-determined
motivation. Briefly, the dietitian had a client-centered approach, put no pressure on
participants about the dietary objectives to be chosen and no emphasis was put on body
autonomous way at the end of the nutritional program and there was no additional
contact with the dietitian after the end of the 12-week intervention. However, men and
138
women were invited to participate to the follow-up period for measurements of
anthropometric and metabolic parameters and completion of questionnaires. This
clinical trial was registered at www.clinicaltrials.gov as NCT01852721.
Measurements of dependent variables
All measurements were performed before (t =0) and after the 12-week nutritional
intervention program (t =3 months), and then 3 and 6 months after the end of the
nutritional intervention (t =6 months and t = 9 months, respectively).
Dietary variables
(27)
dietitian. The FFQ is based on typical foods available in Québec and contains 91 items
and 33 subquestions. Participants were questioned about the frequency of intake of
different foods and drinks during the last month and could report the frequency of these
intakes in terms of day, week or month. As previously described
(6)
, the Medscore was
calculated based on the FFQ and allowed to assess the level of adherence to the
Mediterranean food pattern, which can vary between 0 and 44 points. Components of
the Medscore are: grains (whole and refined); fruits (whole and juices); vegetables
(whole and juices); legumes, nuts and seeds; olive oil (including olives); dairy products;
fish (including seafoods); poultry; eggs; sweets and red meat/processed meat. Briefly, a
high consumption of food groups promoted by the Mediterranean diet (bottom of the
pyramid) (e.g., legumes) contributed to increase the Medscore, whereas a high
consumption of food groups at the top of the Mediterranean pyramid (e.g., red meat)
contributed to decrease the Medscore, as previously described
(6)
. Macronutrient and
micronutrient intakes obtained from the FFQ were evaluated using the Nutrition Data
System for Research (NDS-R, version 4.03_31) software.
Anthropometric and metabolic profile
Height was measured to the nearest millimeter (Seca 222 Mechanical Telescopic
Stadiometer), body weight was measured to the nearest 0.1 kg (BWB-800S Digital
139
scale, Tanita), and body mass index (BMI) was then calculated according to
standardized procedures (28). Waist circumference measure was also taken to the nearest
millimeter according to standardized procedures
(28)
and body fat percentage was
measured using the Tanita body-fat analyser, with the accuracy level being +/− 5% of
the institutional standard of body composition analysis-Dual Energy X-ray
Absorptiometry (DEXA) and repeatable to within +/− 1% variation when used under
consistent conditions (Tanita-BC-418 body-fat analyser (Tanita Corp., Tokyo, Japan))
(29)
. Blood samples were collected after a 12-hour overnight fast. Total-C, HDL-C and
triglyceride concentrations in serum were measured using commercial reagents on a
Modular P chemistry analyzer (with 0.8% and 1.7% of within and between assay
precision, respectively) (Roche Diagnostics, Mannheim, Germany). Serum LDL-C
concentrations were obtained by calculation using the Friedewald equation
(30)
. Plasma
glucose concentrations were measured with the hexokinase enzymatic method (with
0.7% and <1.2% of within and between assay precision, respectively) and plasma
insulin concentrations by electrochimiluminescence (with <2.0% and <2.8% of within
and between assay precision, respectively) (Roche Diagnostics, Mannheim, Germany).
Blood pressure was measured on the right arm and using an automated blood pressure
monitor (BPM 300-BpTRU: Vital Signs Monitor) after 10 minutes rest in the sitting
position and was computed as a mean of three readings which were highly correlated
(systolic blood pressure: 0.85 ≥ r ≤0.91, P <0.0001; diastolic blood pressure: 0.84 ≥ r
≤0.85, P <0.0001).
Eating behaviors
Eating behaviors were assessed by the Three-Factor Eating Questionnaire (TFEQ) (31), a
51-item validated questionnaire which assesses three factors that refer to cognitions and
behaviors associated with eating: dietary restraint (conscious control of food intake with
concerns about shape and weight), disinhibition (overconsumption of food in response
to a variety of stimuli associated with a loss of control on food intake) and hunger (food
intake in response to feelings and perceptions of hunger). More specific subscales can
also be derived from these three general eating behaviors
restraint,
habitual
susceptibility to
disinhibition,
(32, 33)
: rigid restraint, flexible
emotional
susceptibility to
disinhibition, situational susceptibility to disinhibition, internal hunger, and external
hunger.
140
Statistical analyses
Dietary intakes, eating behaviors, anthropometric and metabolic variables measured at
different time points are presented in tables as means ± standard deviations. When
within gender changes are presented they are expressed as percentages of change from
baseline values. The Student’s t-test allowed comparisons of baseline characteristics
between men and women. The Chi-Square test was performed to compare the attrition
rate between men and women. The PROC MIXED procedure, which allow the inclusion
of participants with missing data at some time points
(34)
was also performed. MIXED
procedures for repeated measurements were performed to determine gender, time and
gender by time interactions effects on changes in dependent variables measured (delta
values). Since three different dietitians were in charge of providing the intervention, the
intervener effect was also tested by a MIXED procedure. Delta values were calculated
as post nutritional intervention values (post-nutritional intervention minus prenutritional intervention values) and as follow-up values at 3-month (6 months minus
pre-nutritional intervention values) and 6-month post intervention (9 months minus prenutritional intervention values), respectively. Using this approach, a significant time
effect means that the magnitude of the change is varying with time while a nonsignificant time effect means that changes are maintained with time. Moreover, a
significant gender by time interaction means that the trajectory of changes with time is
not the same in men and women. The Lsmeans procedure, which can be defined as a
linear combination (sum) of the estimated effects, e.g. means, from a linear model and
based on the model used, allowed determining significant changes in outcomes over
time within each gender. When significant gender by time interactions were observed,
simple effects between times and gender were tested to determine precisely the location
of the main interaction effect. Pairwise differences between and within gender were
further tested with the Tukey-Kramer adjustment. Additional analyses were performed
in order to determine if gender differences in changes in dietary intakes, eating
behaviors, anthropometric and metabolic variables were still significant when
accounting for the baseline value. For variables not normally distributed, a
transformation was performed but these variables are presented as raw data in the tables.
In order to determine sample size, we considered a difference of 35% in the change in
Medscore as being clinically significant, based on results of a previous study from our
141
group (6). Therefore, a final sample size of 45 men and 45 women was needed to detect a
gender difference of 35% in the change in Medscore with a power of 0.80 and alpha of
0.05, considering that standard deviation corresponds to 55% of the mean of the change
in Medscore. The probability level for significance used for the interpretation of all
statistical analyses was set at an alpha level of P ≤0.05. All analyses were performed
using SAS statistical software (version 9.2, SAS Institute Inc., Cary, NC).
RESULTS
Table 1 shows characteristics of men and women at baseline in terms of their age,
anthropometric variables, metabolic profile and the quality of their diet as represented
by the Medscore. Men and women included in our study were of similar age, but men
had higher BMI, waist circumference, total-C to HDL-C ratio and triglyceride levels
than women, whereas women had higher percentage of body fat and HDL-C levels than
men. As for global quality of the diet at baseline, women tended to have a higher
Medscore than men. Of the 64 men and 59 premenopausal women included in our study
at baseline, 89%, 78% and 69% of men and 86%, 78% and 75% of women completed
the 12-week nutritional intervention program, and the 3-month and 6-month post
intervention follow-up visits respectively, without significant gender differences in the
attrition rate at any of the three visits. Moreover, men and women who withdrew from
the study presented similar characteristics at baseline to those who completed the
intervention until the end of the follow-up (not shown).
Changes in dietary intakes
Changes in dietary intakes in men and women are presented in Table 2. At the end of
the intervention (t =3 months) as well as 3-month and 6-month post intervention (t =6
months and 9 months, respectively), changes from baseline in energy density and in
percentage of energy intake from lipids and carbohydrates were larger in men than in
women. For these variables, changes were maintained during follow-up as no
significant time effect was observed. Changes observed in dietary fiber intake and in the
percentage of energy intake from saturated fatty acids were also larger in men than in
women. However, for those variables, the magnitude of change decreased with time
142
(time effects; P =0.008 and P =0.0002, respectively). Moreover, although significant
changes in percentage of energy intake from polyunsaturated and trans fatty acids were
observed in both men and women in response to the nutritional intervention, no gender
differences were observed for these variables and they progressively returned towards
baseline values during follow-up (time effects; P =0.004 and P =0.05 for percentage of
energy intake from polyunsaturated and trans fatty acids, respectively). No gender by
time interaction was observed for nutritional intakes, meaning that trajectories of
changes during the follow-up were not significantly different between men and women.
As for the Medscore (Table 3), although a significant increase was observed in men and
women, no gender difference was found in changes measured at the end of the
nutritional intervention and at follow-up visits. However, the Medscore progressively
returned towards baseline values during the follow-up in men and women as shown by
the significant time effect (P <0.0001). Similarly, for olive oil and olives, legumes, nuts
and seeds, and fish and seafood intakes, the magnitude of change decreased with time
(time effects; P =0.01, P <0.0001 and P =0.004, respectively) in both men and women.
On the other hand, gender differences were observed in red and processed meat and
whole fruit intakes, for which changes were larger in men than in women. The
magnitude of change also decreased with time for red and processed meat intake as
indicated by the significant time effect (P =0.0002). No gender by time interaction was
observed for the Medscore and its components, meaning that trajectories of changes
during the follow-up were the same in men and women. Moreover, the change in
Medscore was not influenced by the dietitian in charge of the intervention as indicated
by the analysis of variance (P =0.68).
When dietary changes were adjusted for the baseline value of the response variable
(Tables 2 and 3), gender differences remained significant for dietary fiber intake and
percentage of energy intake from saturated fatty acids only. All other gender differences
initially observed for dietary changes became non-significant after this adjustment.
Moreover, significant gender differences were observed for legumes, nuts and seeds,
whole grain products and egg intakes once adjusted for the baseline value, with greater
increases observed for these variables in men than in women.
143
Changes in anthropometric and metabolic variables
As shown in Table 4, whereas men had significantly lower waist circumference at the
end of the intervention as well as 3-month and 6-month post intervention than at
baseline, women’s waist circumference decreased in response to the intervention but
returned towards baseline values during follow-up (gender by time interaction, P
=0.05). No significant gender differences or time effects were reported for body weight
and percentage of body fat. As for metabolic variables, changes observed in total-C to
HDL-C ratio, triglyceride levels and triglycerides to HDL-C ratio were significantly
more pronounced in men than in women at the end of the nutritional intervention as
well as at the end of follow-up. Moreover, whereas changes in total-C to HDL-C ratio,
triglyceride levels and triglycerides to HDL-C ratio were maintained during follow-up,
the magnitude of change observed in HDL-C levels and diastolic blood pressure tended
to vary with time (time effects; P =0.06 and P =0.07, respectively).
Changes in eating behaviors
Table 5 shows changes in eating behaviors in men and women in response to the 12week nutritional intervention and at 3-month and 6-month post intervention. Overall,
men showed a significant greater decrease in habitual susceptibility to disinhibition than
women and a trend for a more pronounced increase in dietary restraint in men than in
women was observed. Moreover, changes reported in eating behaviors in men and
women were all maintained through the end of the follow-up (no significant time
effect).
DISCUSSION
Our study aimed to document gender differences in long-term effects of a 12-week
nutritional intervention program promoting the adoption of the MedDiet and based on
the SDT on dietary intakes, eating behaviors, anthropometric and metabolic variables, in
men and women presenting risk factors for CVD. Overall, our results showed that most
of the gender differences found in dietary intakes and metabolic profile could be
explained by gender differences in changes occurring during the 12-week intervention
144
since similar levels of maintenance of changes were generally observed in men and
women during the post-intervention period.
No gender difference was observed in the change in adherence to the MedDiet
measured at the end of the follow-up period. However, gender differences were
observed for specific components of the MedDiet, for which more pronounced changes
were found in men than in women. Those changes were also concordant with gender
differences observed in changes in some nutrient intakes. For example, fruits are
recognized for their high fiber content and accordingly, greater increases in fruit as well
as in dietary fiber intakes were observed in men than in women. Similarly, greater
decreases observed in red and processed meat consumption in men than in women are
concordant with greater decreases in saturated fatty acids intake also observed in men.
The fact that these dietary changes were more pronounced in men at the end of followup appears to be explained by the greater amplitude of change observed in dietary
intakes in men than women during the 12-week nutritional intervention. In this regard,
women had baseline dietary habits that were more concordant with principles of the
MedDiet, which might explain why they did not improve as much as men, due to a
ceiling effect
(35)
. This hypothesis is well supported by the fact that many gender
differences in dietary changes were no longer significant once adjusted for the baseline
value of the response variable. However, some differences between men and women
remained significant despite this adjustment for the baseline value, suggesting that other
factors than baseline diet’s characteristics might also explain why dietary changes in
response to the 12-week nutritional intervention were not as important in women as in
men. Accordingly, a previous study has shown that more men than women consider that
not knowing how to take preventive action for CVD was a barrier to cardiovascular
health
(36)
. In line with these previous observations, it is possible that our intervention
was more efficient to overcome barriers more typically identified by men. In fact, our
intervention aimed to support autonomy and competence, especially by improving
nutrition knowledge and skills according to individuals’ needs in order to take action
and apply relevant strategies related to dietary changes. In addition, although the
literature provides a limited understanding of the contexts of help seeking in health
prevention in men, it seems that self-reliance and autonomy remain important for them
(37, 38)
. Therefore, it can be speculated that men might feel more comfortable to choose
145
their own dietary objectives and strategies than women and that the nature of support
offered in our program was more in congruence with men’s needs for the support of
autonomy and competence in the context of food regulation, as suggested by their
greater improvements in overall dietary intakes. In sum, individual characteristics and
intervention components may have contributed to gender differences observed in the
success of men and women in long-term dietary changes and would warrant to be
further considered in the future.
Our results suggest that men and women showed similar limits in maintaining dietary
changes in the longer term. The fact that the study was conducted in a nonMediterranean country could explain some of the results obtained, as supported by
Hoffman and Gerber
(39)
. In fact, when examining the trajectory of changes of the
components of the MedDiet, it can be noticed that intakes of food group that returned
towards baseline values are generally not considered as the most familiar foods for
Quebecers (e.g., legumes and fish intakes)
(40, 41)
or represent a staple in the diet (e.g.,
red and processed meat intake) (42). A greater emphasis in terms of nutritional education
(e.g., alternative choices for more traditional foods, nutritional value of unfamiliar
foods) and culinary skills specifically related to those food groups during the
intervention program might have contributed to a better maintenance of changes in the
long-term. Moreover, a greater emphasis by the dietitian towards the development of a
social network among participants during group sessions could have also been
beneficial for men and women as indicated in the literature
(43, 44)
. In our study, no
additional contact was provided after the end of the 12-week nutritional education
program as we wanted to assess ability of men and women to maintain adherence to the
MedDiet principles in an autonomous way. However, according to the literature, it is
possible that success in long-term diet adherence could have been improved by offering
a program of a lesser intensity but provided on a longer period of time (45).
In addition to gender differences observed in dietary intakes, men and women were
different with regard to eating behaviors. In fact, men showed a greater decrease in
habitual susceptibility to disinhibition than women. Although the focus of the nutritional
intervention program was not on changing eating behaviors, results suggest that more
pronounced dietary changes observed in men in response to the intervention can have
146
led to changes in the regulation of their eating behaviors. Accordingly, we found that an
increase in the Medscore was associated with lower levels of disinhibition in men (data
not shown). Previous studies indicate that different components of the MedDiet seem to
modulate the brain serotonin pathway
(46, 47)
, and findings support the association
between dysregulation of the serotonergic systems and eating disorders (48). Moreover, a
recent study reported that individuals with higher level of adherence to the MedDiet had
lower score for binge eating disorder
(49)
. In line with our results, it can thus be
hypothesized that adherence to the MedDiet pattern could have contributed to
improvements in eating behaviors in men, in part through neurobiological mechanisms.
In addition, as supported by the literature, the high satiating properties of the MedDiet
(50, 51)
may also have contributed to the beneficial impact of the MedDiet on men’s
eating behaviors regulation.
As for anthropometric profile, differences in trajectories of changes with time were
observed between men and women for waist circumference. In agreement with a
previous study
(10)
, improvements in the quality of dietary intakes could have been
beneficial for anthropometric changes in men through a negative energy imbalance. In
this regard, the fact that dietary intakes were self-reported and thus subjected to
different form of bias including underreporting of energy intake which is more common
in women than in men
(52)
might explain why we did not detect significant gender
differences in the reduction of energy intake in response to the intervention.
Furthermore, it is possible that some sex differences could also have contributed to
differences observed in changes in waist circumference between men and women.
Studies have shown that men are more likely than women to experience a preferential
mobilization of abdominal fat in response to lifestyles changes
(53, 54)
. In addition,
changes in eating behaviors observed in men can also have contributed to improve their
anthropometric profile. Indeed, disinhibition has been reported as a strong predictor of
body weight gain
(55)
, and in agreement our results indicate that men with greater
decreases in disinhibition levels tended to have more important decreases in waist
circumference and body weight at follow-up (data not shown).
In accordance with the more important changes in dietary variables and waist
circumference observed in men than in women in response to the intervention, more
147
pronounced decreases in risk factors for CVD were noted in men than in women and
were maintained during follow-up. These results are supported by a review paper
(56)
reporting that a decrease in abdominal obesity is associated with improvements in risk
factors for CVD. Globally, sustained metabolic changes observed in response to the
intervention in men suggest that focusing on the quality of the diet can favour a
decrease in daily energy intake and a decrease in waist circumference, and can thus be
beneficial for optimal management of CVD risk factors, more particularly in men.
This study has important clinical implications that need to be mentioned. The fact that
changes in dietary intakes as well as in the anthropometric and metabolic profile
observed during the 12-week nutritional intervention are determinant of overall longterm changes underlines the importance for health professionals to target efficient and
adapted nutritional approaches. Moreover, a better response to our nutritional
intervention program was observed in men than in women, which indicates the need to
clearly identify facilitating factors and barriers in approaches favouring men and
women’s active involvement in the process of adoption of healthy dietary changes. In
this regard, consideration of qualitative data from focus group with men and women
separately would be a promising avenue. As a perspective, it would be interesting to
assess the impact of this nutritional intervention program in populations of men and
women presenting less healthy dietary intakes before the nutritional intervention.
Although the focus of the present study was to assess gender differences in response to
an intervention promoting the Mediterranean diet, future studies could also add a
control group to further document dietary and metabolic effects of similar nutritional
interventions. Finally, considering the actual context of health prevention, it would also
be relevant to assess outcomes from a similar nutritional education program but of a
lower intensity (i.e. less time-consuming for individuals and requiring less financial
resources) and using technologies such as the Web as part of the counselling sessions.
Overall, these results indicate that the response to the 12-week nutritional intervention
program based on the Self-Determination Theory leads to more pronounced beneficial
changes on long-term dietary intakes in men than in women, contributing to greater
improvements in metabolic profile in men.
148
COMPETING INTERESTS
The authors declare that they have no competing interests.
AUTHORS’ CONTRIBUTION
The authors’ contributions are as follow: VL was in charge of the analysis and
interpretation of data and drafted the manuscript; CB contributed to the conception and
design of the study as well as to the interpretation of data; A-MH and M-MR
contributed to the acquisition of data; LC and SD contributed to the conception and
design of the study; SL (corresponding author) was responsible for the conception and
design of the study and contributed to the interpretation of data. All of the authors have
read and approved the final version of the manuscript submitted for publication.
ACKNOWLEDGEMENTS
This research project was supported by the Canadian Institutes of Health Research
(MOP 84568) and Heart and Stroke Foundation of Quebec (2007–180). Canadian
Institutes of Health Research and Heart and Stroke Foundation of Quebec had no role in
the study design, collection, analysis or interpretation of the data, writing the
manuscript, or the decision to submit the paper for publication. VL is a recipient of a
doctoral scholarship from the Fonds de recherche du Québec - Santé (FRQS).
149
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Table 1. Characteristics of men and women at baseline
Men (n = 64)
Mean
22.7
41.0
30.8
26.7
106.1
3.6
1.1
5.1
1.9
5.3
SD
4.3
7.9
4.4
4.5
10.2
0.7
0.2
1.0
0.9
0.5
Women (n = 59)
Mean
24.1 ¶
41.8
29.6*
39.2*
95.8*
3.6
1.4*
4.2*
1.5*
5.2
SD
3.6
6.7
6.0
6.2
11.5
0.7
0.3
0.9
0.6
0.7
Age (years)
Body fat (%)
LDL-C (mmol/l)
HDL-C (mmol/l)
Total-C/HDL-C ratio
Triglycerides (mmol/l)
SD: Standard deviation.
For percentage of body fat, n =52 men and n =48 women.
For lipid-lipoprotein variables and fasting glucose, n =63 men and n =58 women.
* Values significantly different between men and women (P ≤0.05, Student’s t-test procedure).
¶ Trend for a significant difference between men and women (P =0.06, Student’s t-test procedure).
156
Table 2. Changes in dietary intakes in men and women
Men
Variables
Energy intake (kcal)
Baseline
T = 3 months
T = 6 months
T = 9 months
Energy density (kcal/g) £
Baseline
T = 3 months
T = 6 months
T = 9 months
% Carbohydrates
Baseline
T = 3 months
T = 6 months
T = 9 months
Baseline
T = 3 months
T = 6 months
T = 9 months
Women
Mean
SD
% Change vs.
Mean
Baseline
SD
3065
2768
2757
2759
896
713
752
636
−9.7 *
−10.0 *
−10.0 *
2457
2335
2284
2329
571
527
497
470
1.32
1.21
1.25
1.26
0.24
0.23
0.21
0.21
−8.3 *
−5.3 *
−4.5 *
1.21
1.19
1.16
1.20
0.17
0.17
0.17
0.17
42.2
44.1
43.9
44.4
5.3
5.8
6.3
6.0
4.5 *
4.0 *
5.2 *
44.5
44.8
44.9
44.9
5.8
5.5
5.4
5.6
27.2
32.8
30.1
30.6
9.4
10.8
10.7
11.9
20.6 *
10.7 *
12.5 *
25.6
28.1
25.1
25.2
6.3
7.5
6.0
6.2
Gender
% Change vs. effect
Baseline
P
0.38
−5.0
−7.0 ¶
−5.2
0.02
−1.7
−4.1 ¶
−0.8
0.03
0.7
0.9
0.9
0.003
9.8 *
−2.0
−1.6
Time
effect
Gender x time
interaction
P
0.99
P
0.84
Gender effect
adjusted for
baseline value
P
0.02
0.43
0.11
0.71
0.81
0.74
0.44
0.008
0.90
0.0005
157
Table 2. Changes in dietary intakes in men and women (continued)
Men
Variables
% Proteins
Baseline
T = 3 months
T = 6 months
T = 9 months
% Lipids
Baseline
T = 3 months
T = 6 months
T = 9 months
% MUFA
Baseline
T = 3 months
T = 6 months
T = 9 months
% PUFA
Baseline
T = 3 months
T = 6 months
T = 9 months
158
Women
Mean
SD
% Change vs.
Baseline
Mean
SD
18.3
18.4
18.0
17.9
2.5
2.8
3.0
2.6
0.5
−1.6
−2.2
17.8
17.9
17.6
17.1
2.8
2.9
2.3
2.6
36.8
34.6
34.8
35.1
4.8
5.3
5.2
4.9
−6.0 *
−5.4 *
−4.6 *
35.1
34.6
34.3
35.1
4.5
5.2
4.8
4.8
15.5
15.1
15.2
14.9
2.8
2.9
2.9
2.7
−2.6
−1.9
−3.9 *
14.6
15.1
14.5
15.1
2.7
3.4
2.4
3.3
6.2
6.8
6.4
6.5
1.5
1.6
1.5
1.5
9.7 *
3.2
4.8
5.9
6.3
5.8
5.9
1.4
1.4
1.1
1.2
Gender
% Change vs. effect
Baseline
P
0.99
0.6
−1.1
−3.9 ¶
0.01
−1.4
−2.3
0.0
0.07
3.4
−0.7
3.4
0.93
6.8 *
−1.7
0.0
Time
effect
Gender x time
interaction
P
0.04
P
0.67
Gender effect
adjusted for
baseline value
P
0.40
0.76
0.66
0.25
0.76
0.21
0.58
0.004
0.94
0.10
Table 2. Changes in dietary intakes in men and women (continued)
Men
Women
Gender effect
Gender
Time Gender x time
adjusted for
effect
interaction
Variables
% Change vs.
% Change vs. effect
baseline value
Mean
SD
Mean
SD
Baseline
Baseline
P
P
P
P
% SFA
0.002
0.0002
0.67
0.004
Baseline
12.2
2.7
11.8
1.7
T = 3 months
10.1
2.4
−17.2 *
10.5
2.0
−11.0 *
T = 6 months
10.6
2.4
−13.1 *
11.4
2.5
−3.4
T = 9 months
11.0
2.4
−9.8 *
11.5
2.1
−2.5
% Trans
0.13
0.05
0.33
0.73
Baseline
1.4
0.4
1.3
0.3
T = 3 months
1.1
0.4
−21.4 *
1.1
0.4
−15.4 *
T = 6 months
1.2
0.5
−14.3 *
1.1
0.3
−15.4
T = 9 months
1.3
0.3
−7.1 *
1.1
0.3
−15.4
% Alcohol
0.63
0.14
0.76
0.62
Baseline
2.7
2.4
2.7
2.3
T = 3 months
2.9
2.6
7.4
2.7
2.1
0.0
T = 6 months
3.3
3.1
22.2 *
3.1
2.4
14.8
T = 9 months
2.6
2.4
−3.7
2.9
2.8
7.4
For T = 0, T = 3, T = 6 and T = 9 months, n =64, 57, 50, 44 men and n =59, 51, 46, 44 women, respectively.
MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids; SFA: Saturated fatty acids; Trans: Trans fatty acids.
* P ≤0.05; Significant change within the same gender.
¶ P ≤0.10; Trend for a significant change within the same gender.
£ Including caloric foods and drinks.
159
Table 3. Changes in Medscore and food groups in men and women
Men
Variables
Medscore
(arbitrary units)
Baseline
T = 3 months
T = 6 months
T = 9 months
Olives (portions/d)
Baseline
T = 3 months
T = 6 months
T = 9 months
Whole fruits (portions/d)
Baseline
T = 3 months
T = 6 months
T = 9 months
Whole vegetables
(portions/d)
Baseline
T = 3 months
T = 6 months
T = 9 months
160
Mean
SD
Women
% Change vs.
Baseline
Mean
SD
Gender
Time
effect
effect
% Change vs.
Baseline
P
P
0.25
< 0.0001
22.7
27.6
25.4
24.6
4.3
4.7
4.8
4.6
21.6 *
11.9 *
8.4 *
24.1
27.2
25.8
24.9
3.6
4.9
4.2
5.1
12.9 *
7.1 *
3.3
1.1
1.5
1.4
1.1
1.4
1.1
1.6
0.8
36.4 ¶
27.3
0.0
1.0
1.6
1.0
1.2
0.9
1.7
0.8
1.4
60.0 *
0.0
20.0
1.7
2.6
2.1
2.1
1.4
2.0
1.4
1.6
52.9 *
23.5 *
23.5 *
2.5
2.6
2.6
2.6
1.5
1.4
1.4
1.3
4.0
4.0
4.0
3.8
4.3
4.1
3.7
1.9
2.1
1.9
1.6
13.2 *
7.9
−2.6
4.3
4.3
4.0
4.0
1.4
1.7
1.4
2.0
0.0
−7.0
−7.0
P
0.42
Gender effect
adjusted for
baseline
value
P
0.70
Gender x
time
interaction
0.77
0.01
0.15
0.96
0.04
0.18
0.22
0.68
0.13
0.08
0.76
0.62
Table 3. Changes in Medscore and food groups in men and women (continued)
Men
Variables
Legumes, nuts and seeds
(portions/d) †
Baseline
T=3 months
T=6 months
T=9 months
Whole grain products
(portions/d)
Baseline
T=3 months
T=6 months
T=9 months
Refined grain products
(portions/d)
Baseline
T=3 months
T=6 months
T=9 months
Milk and dairy products
(portions/d)
Baseline
T=3 months
T=6 months
T=9 months
Mean
1.3
1.9
1.6
1.5
3.2
3.7
3.8
3.9
3.3
1.9
2.5
2.2
3.1
2.8
2.7
2.7
SD
1.3
1.2
1.0
1.1
1.7
1.4
2.3
2.1
1.8
1.1
1.9
1.5
2.1
1.8
1.7
1.1
Women
% Change vs.
Baseline
46.2 *
23.1
15.4
15.6 *
18.8 *
21.9 *
-42.4 *
-24.2 *
-33.3 *
-9.7
-12.9
-12.9
Mean
0.8
1.2
0.9
0.9
2.3
2.9
2.8
2.7
2.7
1.9
1.8
2.1
2.6
2.4
2.6
2.6
SD
0.6
0.6
0.5
0.5
1.6
1.3
1.4
1.3
1.6
1.3
1.0
1.2
1.1
1.0
1.4
1.2
Time
effect
Gender x
time
interaction
P
P
Gender effect
adjusted for
baseline
value
P
0.16
< 0.0001
0.57
0.002
0.59
0.86
0.36
0.005
0.54
0.48
0.07
0.51
0.62
0.54
0.74
0.60
Gender
% Change vs. effect
Baseline
P
50.0 *
12.5
12.5
26.1 *
21.7 ¶
17.4
-29.6 *
-33.3 *
-22.2 *
-7.7
0.0
0.0
161
Men
Variables
Poultry (portions/w)
Baseline
T=3 months
T=6 months
T=9 months
Fish and seafood
(portions/w)
Baseline
T=3 months
T=6 months
T=9 months
Red meat/processed
meat (portions/w)
Baseline
T=3 months
T=6 months
T=9 months
Eggs (portions/w)
Baseline
T=3 months
T=6 months
T=9 months
162
Mean
6.4
5.3
4.5
5.0
4.5
7.5
6.8
6.2
SD
4.7
3.8
3.6
3.3
3.5
5.6
5.1
3.7
Women
% Change vs.
Baseline
-17.2
-29.7 *
-21.9
66.7 *
51.1 *
37.8 *
Mean
4.8
4.0
3.9
4.0
3.8
6.2
5.5
4.8
SD
2.9
2.5
2.0
2.7
2.8
4.0
3.3
3.2
Time
effect
Gender x
time
interaction
P
0.24
P
0.83
Gender effect
adjusted for
baseline
value
P
0.12
0.44
0.004
0.95
0.16
0.03
0.0002
0.14
0.83
0.21
0.35
0.51
0.01
Gender
% Change vs. effect
Baseline
P
0.94
-16.7
-18.8 ¶
-16.7
63.2 *
44.7 *
26.3
11.6
5.6
7.8
7.1
6.6
3.8
6.0
5.3
-51.7 *
-32.8 *
-38.8 *
8.0
4.8
5.7
5.8
4.7
3.1
3.5
3.5
-40.0 *
-28.8 *
-27.5 *
3.2
3.3
3.8
3.7
2.7
2.6
3.5
3.0
3.1
18.8 ¶
15.6
2.3
2.1
2.2
2.1
1.7
1.7
1.7
1.9
-8.7
-4.3
-8.7
Men
Women
Gender effect
Gender x
Gender
Time
adjusted for
time
effect
baseline
Variables
% Change vs.
% Change vs. effect
interaction
Mean SD
Mean SD
value
Baseline
Baseline
P
P
P
P
Sweets (portions/w) †
0.95
0.47
0.25
0.23
Baseline
13.8
33.4
9.2
9.1
T=3 months
7.3
12.3
-47.1 *
6.4
6.0
-30.4
T=6 months
9.3
14.3
-32.6
6.5
5.5
-29.3
T=9 months
7.6
5.9
-44.9
8.6
9.3
-6.5
T=9 months
7.6
5.9
-44.9
8.6
9.3
-6.5
For T=0, T=3, T=6 and T=9 months, n = 64, 57, 50, 44 men and n = 59, 51, 46, 44 women, respectively.
SD: Standard deviation; d: day; w: week.
* P ≤ 0.05; Significant change within the same gender.
¶ P ≤ 0.10; Trend for a significant change within the same gender.
† Analysis was performed on transformed values.
163
Table 4. Changes in anthropometric and metabolic variables in men and women
Men
Variables
Body weight (kg)
Baseline
T = 3 months
T = 6 months
T = 9 months
Body fat (%)
Baseline
T = 3 months
T = 6 months
T = 9 months
Waist circumference
(cm)
Baseline
T = 3 months
T = 6 months
T = 9 months
HDL-C (mmol/l)
Baseline
T = 3 months
T = 6 months
T = 9 months
164
Mean
SD
96.6
95.2
94.5
94.2
15.5
14.4
12.4
13.3
26.7
25.6
26.2
25.6
4.5
4.6
5.3
5.0
Women
% Change vs.
Baseline
Mean
SD
% Change vs.
Baseline
−1.4 *
−2.2 *
−2.5 *
77.9
77.2
78.1
77.8
16.2
17.1
17.5
17.5
−0.9 ¶
0.3
−0.1
−4.1 *
−1.9 *
−4.1 *
39.2
39.2
38.9
38.4
6.2
6.6
6.5
6.4
0.0
−0.8
−2.0
106.1
104.2
103.4
103.1
10.2
9.5
8.9
9.9
−1.8 *
−2.5 *
−2.8 *
95.8
94.5
95.0
95.9
11.5
12.6
12.6
12.5
−1.4 *
−0.8
0.1
1.15
1.19
1.20
1.22
0.22
0.25
0.25
0.24
3.5 *
4.3 *
6.1 *
1.44
1.44
1.41
1.46
0.30
0.28
0.28
0.31
0.0
−2.1
1.4 *
Gender
effect
Time
effect
P
0.13
P
0.71
Gender x
time
interaction
P
0.67
0.12
0.86
0.82
0.10
0.39
0.05
0.12
0.06
0.50
Table 4. Changes in anthropometric and metabolic variables in men and women (continued)
Variables
LDL-C (mmol/l)
Baseline
T = 3 months
T = 6 months
T = 9 months
Total-C/HDL-C ratio
Baseline
T = 3 months
T = 6 months
T = 9 months
Triglycerides (mmol/l)
Baseline
T = 3 months
T = 6 months
T = 9 months
Triglycerides/HDL-C ratio
Baseline
T = 3 months
T = 6 months
T = 9 months
Men
% Change vs.
Baseline
Mean
Women
% Change vs.
SD
Baseline
Mean
SD
3.64
3.70
3.61
3.58
0.69
0.64
0.65
0.71
1.6
−0.8 ¶
−1.6
3.65
3.60
3.71
3.73
0.69
0.62
0.76
0.66
−1.4
1.6
2.2
5.08
4.87
4.80
4.60
1.01
0.99
0.97
0.85
−4.1 *
−5.5 *
−9.4 *
4.16
4.06
4.22
4.13
0.86
0.84
0.79
0.78
−2.4
1.4
−0.7
1.89
1.60
1.64
1.61
0.85
0.66
0.70
0.98
−15.3 *
−13.2 *
−14.8 *
1.50
1.36
1.46
1.42
0.58
0.45
0.51
0.52
−9.3
−2.7
−5.3
1.77
1.44
1.49
1.47
0.99
0.76
0.86
1.39
−18.6 *
−15.8 *
−16.9 *
1.10
0.99
1.07
1.02
0.49
0.42
0.44
0.42
−10.0
−2.7
−7.3
Gender
effect
P
0.22
Time
effect
P
0.86
Gender x time
interaction
P
0.15
0.0007
0.18
0.25
0.03
0.09
0.97
0.02
0.14
0.98
165
Variables
Systolic blood pressure
(mm Hg)
Baseline
T = 3 months
T = 6 months
T = 9 months
Diastolic blood pressure
(mm Hg)
Baseline
T = 3 months
T = 6 months
T = 9 months
Baseline
T = 3 months
T = 6 months
T = 9 months
166
Mean
119.78
119.28
118.53
120.36
SD
14.60
10.63
11.50
10.02
Men
% Change vs.
Baseline
−0.4
−1.0
0.5 ¶
Mean
109.22
109.51
111.17
109.26
Women
% Change vs.
SD
Baseline
11.24
11.72
11.61
8.96
Gender
effect
P
Time
effect
P
Gender x time
interaction
P
0.76
0.79
0.27
0.52
0.07
0.90
0.97
0.39
0.84
0.3
1.8
0.04
75.59
72.40
73.97
72.32
9.47
8.48
8.97
7.95
−4.2 *
−2.1
−4.3 *
70.76
68.94
70.19
69.04
7.92
8.17
9.15
6.96
−2.6
−0.8
−2.4
5.27
5.28
5.30
5.38
0.55
0.41
0.43
0.52
0.2
0.6
2.1 ¶
5.16
5.21
5.29
5.17
0.69
0.68
1.19
0.59
1.0
2.5
0.2
Men
Variables
Mean
SD
% Change vs.
Baseline
Women
Mean
SD
% Change vs.
Baseline
Gender
effect
Time
effect
Gender x time
interaction
P
P
P
Fasting insulin
0.99
0.41
0.05
(pmol/l)
100.48
Baseline
44.99 88.53 45.36
T = 3 months
98.95
44.34 −1.5
88.22 40.27
−0.4
T = 6 months
98.70
50.04 −1.8
83.11 36.47
−6.1
T = 9 months
85.77
34.17 −14.6
84.25 38.16
−4.8
For percentage of body fat, T = 0, 3, 6 and 9 months: n =52, 47, 50, 45 men and n =48, 41, 44, 43 women, respectively.
For lipid-lipoprotein variables, T = 0, 3, 6 and 9 months: n =63, 56, 48, 41 (n =40 LDL-C) men and n =58, 51, 44, 44 women.
For fasting glucose and insulin, T = 0, 3, 6 and 9 months: n =64, 57, 50, 44 men and n =58, 51, 44, 44 women.
167
Table 5. Changes in eating behaviors in men and women
Men
Variables
Dietary restraint
Baseline
T = 3 months
T = 6 months
T = 9 months
Flexible restraint
Baseline
T = 3 months
T = 6 months
T = 9 months
Rigid restraint
Baseline
T = 3 months
T = 6 months
T = 9 months
Disinhibition
Baseline
T = 3 months
T = 6 months
T = 9 months
168
Mean
SD
5.9
7.4
8.0
8.4
3.2
3.9
4.7
5.2
1.9
2.4
2.7
3.0
Women
% Change vs.
Baseline
Mean
SD
25.4 *
35.6 *
42.4 *
6.9
7.6
7.3
7.4
4.1
3.9
3.3
3.5
1.4
1.5
1.7
1.9
26.3 *
42.1 *
57.9 *
2.4
2.8
2.8
2.8
1.6
1.6
1.4
1.5
1.7
1.8
2.2
2.2
1.3
1.5
1.9
1.8
5.9
29.4 *
29.4 *
1.8
1.9
1.8
1.9
1.7
1.6
1.4
1.5
6.0
4.9
4.9
4.8
2.8
2.3
2.2
2.2
−18.3 *
−18.3 *
−20.0 *
6.2
5.3
5.3
5.4
2.8
3.0
2.6
3.0
Gender
% Change vs. effect
Baseline
P
0.07
10.1 ¶
5.8
7.2 ¶
0.10
16.7
16.7 ¶
16.7
0.43
5.6
0.0
5.6
0.11
−14.5 ¶
−14.5
−12.9
P
0.88
Gender x
time
interaction
P
0.83
0.41
0.55
0.88
0.19
0.58
0.42
Time
effect
Table 5. Changes in eating behaviors in men and women (continued)
Men
Variables
Habitual susceptibility
to disinhibition
Baseline
T = 3 months
T = 6 months
T = 9 months
Situational susceptibility
to disinhibition
Baseline
T = 3 months
T = 6 months
T = 9 months
Emotional susceptibility
to disinhibition
Baseline
T = 3 months
T = 6 months
T = 9 months
Hunger
Baseline
T = 3 months
T = 6 months
T = 9 months
Mean
0.7
0.4
0.4
0.2
3.0
2.3
2.3
2.2
SD
1.0
0.8
0.6
0.4
1.4
1.3
1.5
1.5
Women
% Change vs.
Baseline
−42.9 *
−42.9 *
−71.4 *
−23.3 *
−23.3 *
−26.7 *
Mean
0.7
0.6
0.4
0.4
2.5
2.0
2.1
2.1
SD
1.0
1.0
0.8
0.8
1.5
1.5
1.4
1.6
P
Gender x
time
interaction
P
0.03
0.75
0.39
0.09
0.77
0.80
0.23
0.22
0.75
0.32
0.81
0.64
Gender
% Change vs. effect
Baseline
P
Time
effect
−14.3
−42.9
−42.9
−20.0 ¶
−16.0
−16.0
0.7
0.7
0.7
0.7
1.0
1.0
0.9
1.0
0.0
0.0
0.0
1.6
1.2
1.2
1.2
1.2
1.2
1.2
1.2
−25.0 *
−25.0
−25.0
4.8
3.3
3.5
3.4
3.0
2.4
2.7
3.0
−31.3 *
−27.1 *
−29.2 *
4.2
3.0
3.0
3.2
2.8
2.7
2.5
2.8
−28.6 *
−28.6 *
−23.8
169
Table 5. Changes in eating behaviors in men and women (continued)
Men
Gender x
Gender
Time
time
effect
Variables
% Change vs.
% Change vs. effect
interaction
Mean SD
Mean SD
Baseline
Baseline
P
P
P
Internal hunger
0.53
0.68
0.35
Baseline
1.9
1.8
1.6
1.6
T = 3 months
1.2
1.4
−36.8 *
0.9
1.4
−43.8 *
T = 6 months
1.3
1.5
−31.6 *
1.0
1.6
−37.5 ¶
T = 9 months
1.2
1.7
−36.8 *
1.1
1.6
−31.3
External hunger
0.57
0.66
0.12
Baseline
1.9
1.5
1.8
1.4
T = 3 months
1.1
1.3
−42.1 *
1.4
1.3
−22.2
T = 6 months
1.4
1.4
−26.3 ¶
1.1
1.1
−38.9 *
T = 9 months
1.4
1.4
−26.3 *
1.4
1.2
−22.2
In men, T = 0: flexible restraint and internal hunger, n =60 and external hunger, n =62; T = 3 months: dietary restraint,
flexible restraint and rigid restraint, disinhibition and habitual susceptibility to disinhibition, internal and external hunger, n =56;
T = 6 months: flexible restraint and external hunger, n =48; T = 9 months: habitual susceptibility to disinhibition and
external hunger, n =43.
In women, T = 0: flexible restraint, habitual susceptibility to disinhibition, internal and external hunger, n =58 and
rigid restraint, n =57; T = 3 months: flexible restraint and internal and external hunger, n =49 and rigid restraint, n =48;
T = 6 months: flexible restraint and habitual susceptibility to disinhibition, n =43 and rigid restraint and external hunger, n =44;
T = 9 months: rigid restraint, n =43.
170
Women
CHAPITRE 6 :
Effets d’un programme d’intervention nutritionnelle
basé sur la théorie de l’autodétermination et visant
l’adoption de l’alimentation méditerranéenne:
différences relatives au genre dans la motivation
autodéterminée et l’adhésion à l’alimentation
méditerranéenne
Vicky Leblanc, Catherine Bégin, Anne-Marie Hudon, Marie-Michelle Royer, Louise
Corneau, Sylvie Dodin, Simone Lemieux
Accepté à Health Psychology Open, 2015
(accepté le 9 septembre 2015)
171
Effects of a nutritional intervention program based on the Self-Determination Theory
and promoting the Mediterranean diet: Gender differences in eating-related
motivation and adherence to the Mediterranean diet
Vicky Leblanc1, Catherine Bégin2, Anne-Marie Hudon1, Marie-Michelle Royer1, Louise
Corneau1, Sylvie Dodin1,3 and Simone Lemieux1.
1
2
3
2440 Hochelaga Blvd
Phone: (418) 656-2131 ext.: 3637
Fax: (418) 656-5877
Keywords : Gender, Theory, Eating, Eating Behaviour, Education, Health Promotion.
Abbreviations: SDT, Self-Determination Theory; MI, Motivational interviewing; CVD,
Cardiovascular diseases; MedDiet, Mediterranean diet; FSH, Follicle-stimulating hormone;
Medscore, Mediterranean score; SDI, Self-determination index; FFQ, Food frequency
questionnaire; BMI, Body mass index.
173
RÉSUMÉ
Cette étude avait pour objectif de déterminer les différences de genre quant à l’impact
d’une intervention nutritionnelle basée sur la théorie de l’autodétermination et visant
l’adoption de l’alimentation méditerranéenne sur les changements de motivation
autodéterminée et d’adhésion à l’alimentation méditerranéenne. Soixante-quatre hommes et
59 femmes préménopausées ont pris part à l’intervention nutritionnelle de 12 semaines
basée sur la théorie de l’autodétermination. L’échelle de régulation du comportement
alimentaire a permis d’évaluer la motivation autodéterminée spécifique au contexte
alimentaire. Un score méditerranéen a été calculé à partir d’un questionnaire de fréquence
alimentaire. Les mesures ont été effectuées avant et après l’intervention de 12 semaines,
ainsi qu’à 6 et 9 mois. Des changements de motivation autodéterminée plus prononcés chez
les hommes que chez les femmes ont été observés en réponse à l’intervention ainsi qu’à la
fin du suivi, avec une diminution de l’ampleur du changement dans le temps chez les
hommes et les femmes. Une association positive entre les changements de motivation
autodéterminée et le score méditerranéen a été notée en réponse à l’intervention et au suivi
chez les hommes seulement. Globalement, l’intervention nutritionnelle semble avoir été
plus efficace auprès des hommes que des femmes considérant que les changements de
motivation autodéterminée étaient associés à l’augmentation de l’adhésion à l’alimentation
méditerranéenne chez les hommes seulement.
175
ABSTRACT
No previous study examined the impact of motivation quality on adherence to healthy
eating recommendations using a gender perspective. Our objective was to determine gender
differences on the impact of a nutritional intervention based on the Self-Determination
Theory and promoting the Mediterranean diet (MedDiet) on changes in eating-related selfdetermined motivation and adherence to the MedDiet. Sixty-four men and 59
premenopausal women presenting risk factors for cardiovascular disease were recruited in a
12-week nutritional intervention program based on the Self-Determination Theory. The
Regulation of Eating Behavior Scale allowed assessment of eating-related self-determined
motivation. A food frequency questionnaire allowed calculation of a Mediterranean score.
Measurements were performed at baseline, after the 12-week intervention, and at 6 and 9
months. Changes in eating-related self-determined motivation were larger in men than in
women in response to the intervention and at follow-up, but the magnitude of change
decreased with time in both genders. Changes in eating-related self-determined motivation
were positively associated with changes in the MedDiet adherence in response to the
intervention and at follow-up in men only. Overall, our nutritional program seems to fit
better men than women as changes in eating-related self-determined motivation were
associated to increases in adherence to the MedDiet in men only.
177
INTRODUCTION
A better understanding of the motivation to engage in health behaviors is essential. Up to
now the focus has mainly been on the quantitative dimension of motivation
(1)
. Deci and
Ryan with the Self-Determination Theory (SDT) emphasize the importance of motivation
quality
(2, 3)
. In fact, this theory proposes that the regulation of a behavior may take many
forms that correspond to different behavioral regulatory styles according to motivation
differing by their self-determination level, and which can be differentiated along a
continuum. Moreover, according to the SDT, different self-determined regulatory styles are
associated with various consequences. In fact, self-determined forms of motivation are
associated with positive consequences and least self-determined forms of motivation with
more negative consequences. Another key postulate from the SDT addresses the processes
that facilitate internalization of nonself-determined regulatory styles towards more selfdetermined regulatory styles
(2, 3)
if supportive conditions are in place, i.e., a context that
fosters satisfaction of three basic psychological needs which are autonomy, competence,
and relatedness. With regard to the regulation of eating behaviors, previous studies showed
that behaviors regulated by self-determined motivation promote adoption of healthy eating
behaviors and long-term maintenance of healthy eating habits
(4, 5)
, and could also be a
protective factor against social pressures unfavourable to healthy eating behaviors (4, 6).
Evidence suggests that a person will be more likely to develop and maintain more selfdetermined motivation in a context that is autonomy-supportive
(7, 8)
. Autonomy support
refers to eliciting and acknowledging a person’s perspectives and values, supporting
initiatives, offering options and providing relevant information while minimizing
persuasion and control
(9)
. Development of autonomy-supportive nutritional approaches
aimed to promote self-determined motivation seems promising in the context of prevention
of cardiovascular diseases (CVD) since sustained healthy dietary changes can improve
many risk factors.
Benefits of the Mediterranean diet (MedDiet) on health is well established in the literature
179
and the MedDiet is now recognized as one of the best models of food patterns providing
protection against chronic diseases, such as CVD
(10, 11)
. Although feasibility to adopt the
MedDiet principles among non-Mediterranean population has been previously reported,
maintenance of dietary changes remains a challenge on the long term
(12, 13)
and might be
improved by considering motivational factors related to eating regulation.
It has been reported that differences between men and women exist with respect to eating
habits
(14, 15)
. Therefore, gender differences in motivational factors related to eating
regulation need to be examined and considered within nutritional approaches to improve
their effectiveness. In this sense, gender differences in the level of eating-related selfdetermined motivation were previously reported, with women reporting higher level of
self-determined motivation than men
(16)
. However, potential differences between men and
women related to changes in self-determined motivation in response to a nutritional
intervention based on the SDT remain unknown.
Only few studies examined self-determined motivation in a dietary context. More
importantly, none has focused on gender differences in the impact of a nutritional
intervention aimed at increasing self-determined motivation. The objective of this study
was therefore to determine gender differences in short and longer-term effects of a 12-week
nutritional intervention program promoting the adoption of the MedDiet and based on the
SDT on changes in eating-related self-determined motivation and in adherence to the
MedDiet.
180
METHODOLOGY
Participants
between 25 and 50 years old, and recruited through different media advertisements in the
Québec City Metropolitan area, Canada. In women, a follicle-stimulating hormone (FSH)
measurement was performed if needed (e.g., when women presented periods irregularities)
to confirm the premenopausal status (FSH < 20 IU/L)
(17)
. Men and women had to present
slightly elevated LDL-C concentrations, i.e. between 3.0 and 4.9 mmol/L (18) or a total-C to
HDL-C ratio ≥ 5, and at least one of the four following criteria of the metabolic syndrome
(19)
: 1) triglyceride concentrations ≥ 1.7 mmol/L; 2) fasting glycaemia between 6.1 and 6.9
mmol/L; 3) blood pressure measurements ≥ 130/85 mm Hg; 4) waist circumference ≥ 80
cm in women and ≥ 94 cm in men (20). Participants also had to have a stable body weight (
2.5 kg) for a minimum of three months prior to the beginning of the study and to be
involved in food purchases and/or preparation at home. Men and women who had
cardiovascular events and used medication that could affect dependent variables under
study, i.e., hypertension, dyslipidemia and diabetes were excluded. Pregnant women,
smokers, participants with an alcoholism history or with a high Mediterranean score
(Medscore > 29, i.e. food pattern already highly concordant with the MedDiet)
(13)
were
also excluded. All subjects voluntarily agreed to participate in the research project and
written informed consent was obtained from all men and women prior to their participation
in the study. This study was approved by the Laval University Research Ethics Committee.
Previous publications using data from those participants examined gender differences in
dietary, anthropometric and metabolic changes
(21, 22)
, but did not assess motivational
mechanism through which those changes occurred following a nutritional intervention
based on SDT within a gender perspective.
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Study Design
The 12-week nutritional program was based on the Self-Determination Theory (SDT). This
theory relies on the quality of the motivation that regulates behaviors and lies on a
continuum from lower to higher self-determined motivation forms (extending from
amotivation to intrinsic motivation) (3) (Figure 1). Dietitians who provided the intervention
used a motivational interviewing (MI) approach. MI is a practical set of intervention
strategies well-developed and field-tested in the context of clinical interventions
(9)
and is
largely consistent with SDT premises on motivation and lasting behavior change. MI has
been used to test SDT constructs (Vansteenkiste and Sheldon, 2006; Patrick and Williams,
2012). The study was conducted into small groups (from January 2010 to November 2012)
and the nutritional intervention included three group sessions, three individual sessions and
four follow-up phone calls with a registered dietitian (Figure 2). Three registered dietitians
were trained to provide a standardized intervention and participants always met with the
same dietitian during individual sessions. The first group session was a lecture, always
provided by the same dietitian and aiming at explaining principles of the traditional
MedDiet (length: 2.5 hours, n = 13-25 participants/group). At week four, men and women
actively participated in a 3-hour Mediterranean cooking lesson during which they had to
cook a Mediterranean meal (n = 8-14 participants/group). At week eight, they shared a 3hour Mediterranean potluck dinner aimed at discussing barriers met in adopting dietary
recommendations since the beginning of the intervention (n = 5-12 participants/group).
Face-to-face individual counselling took place at weeks one, five and 10 and lasted between
45 minutes and one hour for each appointment. Individual follow-up phone calls took place
at weeks three, six, nine and 12, and each lasted for about 20-30 minutes. The main
objective of face-to-face individual counselling and follow-up phone calls was to assess
dietary changes and to determine, with an autonomy-supportive climate, progressive
personal goals with potential and realistic strategies aimed at improving the adherence to
MedDiet principles. Different tools congruent with the SDT tenets were used during these
sessions to formulate dietary objectives while increasing self-determined motivation. More
precisely, the decisional balance allowed assessment of pros and cons of keeping dietary
habits stable as well as pros and cons of changing dietary habits. The action plan was used
182
to determine concrete dietary objectives, i.e. the starting point for the change, frequency of
adoption of the behavior, perceived benefits from the behavior change, main strategies
considered to achieve the change, actions planned to overcome barriers and potential
people who would support them into their process of dietary changes. In accordance with
the SDT
(3)
, basic psychological needs (i.e. autonomy, competence and relatedness) were
supported during the nutritional intervention in order to increase self-determined
motivation. The dietitian had a client-centered approach and put no pressure on participants
about the type of dietary objectives to be chosen. In addition, no emphasis was put on body
autonomous way at the end of the nutritional program and there was no additional contact
with the dietitian after the end of the 12-week intervention.
intervention program (t = 3 months), and then 3 and 6 months after the end of the
nutritional intervention (t = 6 months and t = 9 months, respectively).
The Regulation of eating behaviors scale
(4)
people close to me insist that I do”), and amotivation (e.g., “I don’t know why I bother”).
Evaluation of the internal consistency of the subscales revealed to be adequate (Cronbach’s
183
alphas ranged from 0.79 to 0.91). Each item is measured on a 7-point Likert scale, which
allows calculation of the self-determination index (SDI) (23), specific to eating regulation.
Health Care Climate
The Health Care Climate Questionnaire is a 15-item validated questionnaire
(24)
which
assesses clients’ perception of the degree to which their practitioner is autonomysupportive. In our study, the word “practitioner” was replaced by the word “dietitian”.
Cronbach alpha reliability for the 15 items of this questionnaire has consistently been above
0.90. This scale includes three dimensions considered essential for an optimally supportive
health care context, which reflect autonomy support (e.g., “I feel that the dietitian has
provided me choices and options”), involvement (e.g., “The dietitian handles peoples’
emotions very well”) and structure (e.g., “The dietitian has made sure I understand the links
between foods and health and which dietary changes I can do to improve my diet”). Each
item is measured on a 7-points scale (from disagree to strongly agree) and allows
calculation of a global score (range 15-105), with a higher average score representing a
higher level of perceived autonomy support.
Dietary Variables
(25)
dietitian. The FFQ is based on typical foods available in Québec and contains 91 items and
terms of day, week or month. As previously described
(13)
, the Medscore was calculated
based on the FFQ and allowed to assess the level of adherence to the Mediterranean food
pattern, which could vary between 0 and 44 points. Components of the Medscore are:
grains (whole and refined); fruits (whole and juices); vegetables (whole and juices);
legumes, nuts and seeds; olive oil (including olives); dairy products; fish (including
seafoods); poultry; eggs; sweets and red meat/processed meat. Briefly, a high consumption
of food groups promoted by the Mediterranean diet (bottom of the pyramid) (e.g., legumes)
contributed to increase the Medscore, whereas a high consumption of food groups at the top
184
of the Mediterranean pyramid (e.g., red meat) contributed to decrease the Medscore, as
previously described (13).
Anthropometric Profile
According to standardized procedures
(26)
height was measured to the nearest millimeter
with a stadiometer (Seca 222 Mechanical Telescopic Stadiometer), body weight was
measured to the nearest 0.1 kg on a calibrated balance (BWB-800S Digital scale, Tanita),
and body mass index (BMI) was then calculated. Waist circumference measure was also
taken to the nearest millimeter according to standardized procedures (26).
All analyses were performed using SAS statistical software (version 9.2, SAS Institute Inc.,
Cary, NC). The Student’s t-test allowed comparisons of baseline characteristics, and also
the health-care climate, between men and women. Motivational variables measured are
presented as means  standard deviations for the baseline value but otherwise as changes 
standard deviations. MIXED models for repeated measurements, which allows the
inclusion of participants with missing data at some time points
(27)
, were performed to
determine gender, time and gender by time interactions effects on changes in dependent
variables measured (delta values). Delta values were calculated as post nutritional
intervention values (post-nutritional intervention minus pre-nutritional intervention values)
and as follow-up values at t = 6 months (6 months minus pre-nutritional intervention
values) and at t = 9 months (9 months minus pre-nutritional intervention values),
respectively. Using this approach, a significant time effect means that the magnitude of the
change is varying with time while a non-significant time effect means that changes are
maintained with time. Moreover, a significant gender by time interaction means that the
trajectory of changes with time is not the same in men and women. The Lsmeans
procedure, which can be defined as a linear combination (sum) of the estimated effects, e.g.
means, from a linear model and based on the model used, allowed determining significant
185
changes in outcomes over time within each gender. Pairwise differences between and
within gender were further tested with the Tukey-Kramer adjustment. Pearson correlation
analyses were performed to examine associations between eating-related SDI, adherence to
the Medscore and BMI, in men and women separately. Afterwards, covariance analyses
(Lsmean procedure) were performed to determine whether an interaction between gender
and changes in eating-related SDI explains changes in the Medscore, and whether or not
this relation remains the same after controlling for baseline eating-related SDI. For
variables not normally distributed, a transformation was performed but these variables are
presented as raw data in the tables. For determination of sample size, we considered a
difference of 35% in the change in Medscore as being clinically significant, based on
previous results (13). Therefore a final sample size of 45 men and 45 women was needed to
detect a difference of 35% in the change in Medscore between men and women with a
power of 0.80 and alpha of 0.05, considering that standard deviation corresponds to 55% of
the mean of the change in Medscore. The probability level for significance used for the
interpretation of all statistical analyses was set at a  level of P  0.05.
RESULTS
Table 1 shows characteristics of men and women at baseline. Men and women were about
the same age, but men had higher BMI, waist circumference, total-C to HDL-C ratio and
triglyceride levels than women, whereas women had higher HDL-C levels than men. Of the
64 men and 59 premenopausal women included in our study at baseline, 89%, 78% and
69% of men and 86%, 78% and 75% of women completed assessments at the end of the
12-week nutritional intervention program (t = 3 months), and at t = 6 months and t = 9
months post intervention follow-up visits respectively, without significant gender
differences in the attrition rate at any of the three visits. Moreover, men and women who
withdrew from the study presented similar characteristics at baseline to those who
completed the intervention until the end of the follow-up (not shown).
186
Level of perceived autonomy support from the dietitian
No gender difference was observed for the health care climate measured at the end of the
nutritional intervention, i.e., men and women similarly perceived that their dietitian was
autonomy-supportive during the 12-week nutritional intervention program (98.0 ± 8.5 in
men and 97.6 ± 8.9 in women; t-test, P = 0.81).
Changes in eating-related self-determined motivation and in adherence to the
MedDiet
Changes in eating-related SDI and its different subscales of regulatory styles in men and
women are presented in Table 2. Changes observed in eating-related SDI were larger in
men than in women in response to the 12-week nutritional intervention and at follow-up
(gender effect, P = 0.04). Similarly, a trend for larger changes was observed in integrated
regulatory style in men than in women in response to the intervention and at follow-up
(gender effect, P = 0.08). However, for these variables, the magnitude of change decreased
with time (time effects, P = 0.0002 for eating-related SDI and P = 0.008 for integrated
regulation). Significant changes in intrinsic motivation were observed in both men and
women in response to the intervention, but no gender difference was observed. Moreover,
this variable tended to return towards baseline values during follow-up (time effect, P =
0.08). Although significant decreases in amotivation were observed in response to the
nutritional intervention in men only, no gender difference was observed, and this variable
progressively returned towards baseline values during follow-up in both men and women
(time effect, P = 0.002). No gender by time interaction was observed for changes in eatingrelated SDI nor its different subscales, meaning that trajectories of changes during the
follow-up were not significantly different between men and women. When changes in
eating-related SDI and its subscales of regulatory styles were adjusted for the baseline
value of the response variable, significant gender differences and trend for gender
differences initially observed all became non-significant.
As for changes in adherence to the MedDiet, a significant increase was observed in the
Medscore in men and women in response to the nutritional intervention and at follow-up
(22.7 ± 4.3, 27.6 ± 4.7, 25.4 ± 4.8, 24.6 ± 4.6 units in men and 24.1 ± 3.6, 27.2 ± 4.9, 25.8 ±
187
4.2, 24.9 ± 5.1 units in women, at baseline, after the 12-week nutritional intervention, at t =
6 months and t = 9 months, respectively), but without gender differences (gender effect, P
= 0.25). However, the Medscore progressively returned towards baseline values during the
follow-up in men and women with a significant time effect (time effect, P < 0.0001).
Moreover, no gender by time interaction was observed for the Medscore, meaning that
trajectories of changes during the follow-up were the same in men and women (gender by
time interaction, P = 0.42). Regarding changes in BMI, significant decreases were observed
in both men and women after the end of the nutritional intervention and at follow-up (30.8
± 4.4, 30.2 ± 4.0, 30.1 ± 3.5, 30.0 ± 3.8 kg/m2 in men and 29.6 ± 6.0, 29.4 ± 6.0, 29.7 ± 6.2,
29.6 ± 6.3 kg/m2 in women, at baseline, t = 3 months, t = 6 months and t = 9 months,
respectively), but no gender differences were found (gender effect, P = 0.18).
Pattern of associations between eating-related SDI and adherence to the MedDiet
according to gender, in response to the 12-week intervention and at follow-up
In men, a significant and positive association was found between changes in eating-related
SDI and changes in the Medscore in response to the intervention (r = 0.41, P = 0.002), as
well as between changes observed in these variables at t = 9 months (r = 0.39, P = 0.009)
(Table 3). Also, a trend for a negative association between changes in eating-related SDI
and changes in BMI (r = -0.26, P = 0.06) was observed in response to the intervention in
men, and this negative association was significant for changes measured at t = 9 months (r
= -0.33, P = 0.03). In women, no association was observed between changes in eatingrelated SDI and changes in the Medscore measured either at the end of the intervention (r =
-0.08, P = 0.57) or at follow-up (r = -0.03, P = 0.84) (Table 3). Moreover, although no
association was found between changes in eating-related SDI and changes in BMI in
response to the intervention in women, a significant and negative association was observed
between changes in these variables measured at t = 9 months (r = -0.40, P = 0.007).
Additional analyses were performed to further document the differences observed between
men and women in the association between changes in SDI and changes in the Medscore.
Accordingly, a significant interaction was observed between gender and changes in eatingrelated SDI in the determination of changes in the Medscore in response to the intervention
188
(interaction, P = 0.02). In order to verify if higher baseline level of eating-related SDI
found in women would contribute to explain this interaction (i.e, differences between men
and women in the association between changes in SDI and changes in the Medscore),
baseline level of eating-related SDI was added to the model of covariance. It was found that
the interaction between gender and changes in eating-related SDI in the determination of
changes in the Medscore remains significant despite adjustment for baseline level of eatingrelated SDI in response to the intervention (interaction, P = 0.03). At t = 9 months, no
significant interaction (interaction, P = 0.12) was found between gender and changes in
eating-related SDI in the determination of changes in the Medscore.
DISCUSSION
The aim of our study was to determine gender differences in the impact of a nutritional
intervention program based on the SDT and promoting the MedDiet on eating-related
motivation and adherence to the MedDiet. Results indicate that men and women perceived
the motivational approach as autonomy-supportive in a similar manner although it led to
larger increases in self-determined motivation in men than in women. Moreover, increases
in eating-related self-determined motivation were associated with increases in adherence to
the MedDiet in men only.
Changes observed in eating-related self-determined motivation evolved in a similar
direction in men and women as no gender by time interaction was observed. However,
larger increases in eating-related self-determined motivation were observed in men than in
women in response to the 12-week intervention and at follow-up. The SDT posits that a
context fostering satisfaction of autonomy, competence, and relatedness is essential in
promoting self-determined motivation (2, 3). Accordingly, different aspects of our nutritional
intervention aimed at promoting satisfaction of these psychological needs. More precisely,
competence of men and women was promoted by the Mediterranean cooking lesson, the
Mediterranean potluck dinner and by nutritional information and practical tools discussed
during individual and group sessions. The need for relatedness was fostered by the
189
development of a relationship based on trust, consideration and collaboration between the
dietitian and the participant, by the group cohesion promoted between participants during
group sessions and also by the consideration of important others in the action plan for
dietary changes. Then, autonomy was supported when individuals had to determine their
personal dietary objectives, the best strategies regarding the objectives and the key factors
to overcome barriers. Moreover, recipes and nutritional tools were not automatically
provided to individuals but rather given according to individuals’ needs.
In regard to the impact of our intervention in men and women, factors that can explain why
women did not increase their level of eating-related self-determined motivation as much as
men, such as level of eating-related self-determined motivation at baseline, need to be
considered. Indeed, as women reported higher level of eating-related self-determined
motivation than men at baseline, room for improvement in motivation could have been
more limited for women than men. In this regard, the adjustment for the baseline value of
the response variable indicated that if a similar level of eating-related self-determined
motivation at baseline had been observed in men and women, no significant gender
difference would have been found in changes in eating-related self-determined motivation.
In addition, despite the fact that men and women perceived the intervention as similarly
autonomy-supportive, it can be hypothesized that gender differences exist in the level of
need satisfaction for autonomy, competence and relatedness specific to the dietary context.
However, to our knowledge, no validated questionnaire allows assessment of the
satisfaction of the psychological needs specific to the dietary context. Moreover, a better
understanding of the impact of the health care climate in men and women on changes in
eating-related self-determined motivation could be achieved in future studies by assessing
perceived level of satisfaction of the psychological needs at different time-points of an
intervention. Indeed, data from a recent qualitative study in the field of physical activity
reported that satisfaction of the needs for competence and relatedness were essential during
the phase of adoption of the exercise behavior while satisfaction of autonomy had more
impact in the maintenance phase
(28)
. Those results suggest that stages of development of
these needs might differ and should be considered in order to facilitate internalization of
nonself-determined regulatory styles towards more self-determined regulatory styles. In
190
addition, the idea of monitoring people on a daily basis using an ecological momentary
assessment technique could be interesting as previous studies reported within-person
fluctuations in psychological need satisfaction (Verstuyf et al., 2013).
The fact that eating-related self-determined motivation returned toward baseline values in
both men and women underlines the difficulty to maintain motivation changes. Despite
twelve weeks of intervention aimed to internalize motivational factors related to the
adoption of a diet of better quality, the transition between the end of the intervention
program and the follow-up period, and the complete absence of support during the followup seem to represent critical points to consider. Moreover, intrinsic motivation, i.e. highest
level of eating-related self-determined motivation and which refers to undertaking an
activity for its inherent interest and enjoyment, might be more difficult to maintain than
other types of motivation
(9, 29)
. This can partly be explained by the fact that the delay to
internalize intrinsic motivation might have been insufficient. It is also possible that attempts
to maintain dietary intakes were directed more to other outcomes such as to improve health
condition or decrease body weight, which could have thwarted the intrinsic motivation
towards changing dietary habits per se (e.g. for the interest and pleasure of eating or
preparing food according to the MedDiet)
(29)
. Although the magnitude of the changes in
eating-related self-determined motivation also decreased with time among men, level of
motivation remained significantly higher than at baseline, suggesting a non-negligible
impact from the nutritional intervention program on motivational factors. In addition,
previous results demonstrate that our intervention based on a motivational approach had a
beneficial impact on the adoption of healthy dietary intakes and risk factors for CVD such
as waist circumference and lipid profile, more particularly in men (26, 27).
To our knowledge, assessment of the influence of changes in motivation on changes in the
adherence to the MedDiet according to gender is a novelty in the literature. We found that
an increase in eating-related self-determined motivation was associated with an increase in
the adherence to the MedDiet in response to the 12-week intervention as well as at followup, in men but not in women. Moreover, additional analyses revealed that differences found
between men and women in the association between changes in motivation and changes in
191
adherence to the MedDiet may not be explained by gender differences in the level of
eating-related self-determined motivation at baseline. This suggests that other genderrelated factors are involved to explain these differences in the pattern of associations
between eating-related self-determined motivation and adherence to the MedDiet. Those
factors may be related to eating-related attitudes, behaviors and norms, societal role and
responsibilities attributed to men and women
(30, 31)
. Although these factors were not
specifically assessed in our study, some components of the nutritional intervention program
may have better suited men than women. Previous studies indicate that men are more
ambivalent than women towards healthy eating choices
(32, 33)
therefore supporting our
hypothesis that tools used in our intervention and aimed at increasing eating-related selfdetermined motivation such as the decisional balance might have been more beneficial for
men than women.
As no previous study assessed gender differences in changes in eating-related selfdetermined motivation, several hypotheses remain to be verified in the future regarding
basic psychological needs for autonomy, competence and relatedness in the dietary context
and potential moderators in the association between changes in motivation and changes in
dietary intakes to allow a better understanding of the influence of the quality of the
motivation in the context of healthy eating in both men and women. The fact that men and
women recruited in our study were middle-aged adults and presented specific
characteristics regarding CVD risk limits the generalization of our results to the whole
population. Moreover, although missing data could contribute to overestimate changes
found at follow-up in self-determined motivation in men and women, gender differences
observed are unlikely to be influenced by this possible bias since the attrition rate was the
same in men and women. Nevertheless, this study has important strengths and clinical
implications that need to be mentioned. Our nutritional education program was developed
based on the Self-Determination theory, which facilitated and guided our methods of
intervention. Moreover, this study design allowed the assessment of long-term impact of a
nutritional intervention, during which individuals were actively involved in the process of
dietary changes followed by a 6-month period with no additional support provided which
can be more representative of a real-life setting.
192
Overall, although both men and women increased their adherence to the MedDiet in
response to the nutritional intervention, results indicate that the nutritional intervention
program aimed at promoting eating-related self-determined motivation in order to improve
the quality of the diet seems to fit better men than women as changes in eating-related selfdetermined motivation were associated with increases in adherence to the MedDiet in men
only.
FINANCIAL SUPPORT
decision to submit the paper for publication. The first author is a recipient of a doctoral
scholarship from the Fonds de recherche du Québec - Santé (FRQS).
AUTHORSHIP
design of the study as well as to the interpretation of data; A-M.H. and M-M.R. contributed
to the acquisition of data; L.C. and S.D. contributed to the conception and design of the
study; S.L. (corresponding author) was responsible for the conception and design of the
study and contributed to the interpretation of data. All of the authors have read and
approved the final version of the manuscript submitted for publication.
193
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197
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Table 1. Characteristics of men and women at baseline
Men (n =64)
Women (n =59)
Mean
SD
Mean
SD
Age (years)
41.0
7.9
41.8
6.7
2
Body mass index (kg/m )
30.8
4.4
29.6*
6.0
106.1
10.2
95.8*
11.5
Total cholesterol (C) (mmol/L)
5.7
0.8
5.8
0.8
LDL-C (mmol/L)
3.6
0.7
3.6
0.7
HDL-C (mmol/L)
1.1
0.2
1.4*
0.3
Total-C/HDL-C ratio
5.1
1.0
4.2*
0.9
Triglycerides (mmol/L)
1.9
0.9
1.5*
0.6
Fasting glucose (mmol/L)
5.3
0.5
5.2
0.7
* Mean values were significantly different between men and women
(P ≤ 0.05, Student's t test).
Measurements of blood lipids and glucose levels were performed in 63 men and in
58 women.
201
Table 2. Changes in the eating-related self-determination index and its specific forms of regulation in men and women in response to
the 12-week nutritional intervention program and at follow-up
Men
Variables
Intrinsic motivation
Baseline §
Δ 0-3 months
Δ 0-6 months
Δ 0-9 months
Integrated regulation
Baseline §
Δ 0-3 months
Δ 0-6 months
Δ 0-9 months
Identified regulation
Baseline
Δ 0-3 months
Δ 0-6 months
Δ 0-9 months
Introjected regulation
Baseline
Δ 0-3 months
Δ 0-6 months
Δ 0-9 months
202
Mean
5.27
0.37 *
0.36 *
0.22 ¶
4.88
0.57 *
0.61 *
0.44 *
6.23
0.08
0.15
-0.13
2.35
-0.04
0.005
-0.06
Women
SD
1.05
0.86
0.82
0.90
1.18
0.96
1.03
1.28
0.70
0.96
1.03
1.28
1.01
0.65
0.90
0.73
Mean
5.78
0.28 *
0.27 ¶
0.18
5.32
0.28 *
0.37 *
0.11
6.33
-0.08
-0.13
-0.11
2.30
-0.06
0.07
0.18
SD
Gender
differences
adjusted for
baseline value
Gender
differences
Time
effect
Gender x
time
interaction
P
P
P
P
0.49
0.08
0.93
0.40
0.08
0.008
0.95
0.48
0.33
0.14
0.14
0.57
0.55
0.17
0.39
0.68
0.87
0.86
0.75
0.70
1.04
0.81
0.71
0.71
0.64
0.52
0.73
0.53
0.93
0.75
0.78
0.76
Table 2. Changes in the eating-related self-determination index and its specific forms of regulation in men and women in response to
the 12-week nutritional intervention program and at follow-up (continued)
Men
Women
Gender
Gender x
Gender
Time
differences
time
differences
effect
adjusted for
Variables
interaction
Mean
SD
Mean
SD
baseline value
P
P
P
External regulation
0.23
0.0454
0.86
Baseline §
1.95
1.05
1.63
0.72
Δ 0-3 months
-0.16
0.72
-0.04
0.60
Δ 0-6 months
-0.10
0.83
0.04
0.73
Δ 0-9 months
-0.03
0.83
0.17
0.70
Amotivation
0.10
0.002
0.70
Baseline
1.38
0.49
1.22
0.42
Δ 0-3 months
-0.15 *
0.52
0.01
0.42
Δ 0-6 months
-0.19 *
0.52
-0.09
0.44
Δ 0-9 months
-0.09
0.58
0.09
0.41
Eating related selfdetermination index
0.04
0.0002
0.97
Baseline §
21.33
6.43
25.08
6.58
Δ 0-3 months
3.17 *
5.83
1.43 ¶
4.20
Δ 0-6 months
3.31 *
5.66
1.56 ¶
4.48
Δ 0-9 months
1.85 *
6.89
-0.13
3.96
SD, Standard deviation.
Δ 0-3 months, Changes from baseline to the end of the 12-week nutritional intervention; Δ 0-6 months, Changes from
baseline to 3-month post intervention; Δ 0-9 months, Changes from baseline to 6-month post intervention.
§ Mean value significantly different between men and women (P ≤ 0.05, Student's t test).
P
0.45
0.43
0.49
203
In men, for T = 0, Δ 0-3 months, Δ 0-6 months and Δ 0-9 months, n =63, 56, 49 and 44, except for integrated regulation
(n =62, 55, 48 and 43 respectively).
In women, for intrinsic motivation (n=59, 49,44 and 44); integrated regulation (n =59, 49, 43 and 43); identified regulation
(n =58, 49, 43 and 43); introjected regulation (n =59, 50, 44 and 44); external regulation (n =59, 49, 43 and 44); amotivation
(n =59, 50, 44 and 44); Eating related self-determination index (n =59, 50, 44 and 44).
204
Table 3. Associations between changes in eating-related self-determined motivation and changes in the Medscore and
in BMI in men and women
Δ Eating-related SDI (0-3 months)
Men (n =56)
Δ Eating-related SDI (0-9 months)
Women (n =50)
Men (n =44)
Women (n =44)
r
P
r
P
r
P
r
P
Δ Medscore (0-3 months)
0.41
0.002
-0.08
0.57
-
-
-
-
Δ Medscore (0-9 months)
-
-
-
-
0.39
0.009
-0.03
0.84
-0.26
0.0562
-0.22
0.13
-
-
-
-
0.03
-0.40
0.007
Δ BMI (0-3 months)
Δ BMI (0-9 months)
-0.33
Δ 0-3 months, Changes from baseline to the end of the 12-week nutritional intervention;
Δ 0-9 months, Changes from baseline to 6-month post intervention.
Eating-related SDI, eating-related self-determination index.
For Δ Medscore (0-9 months) in women, n =43.
205
CHAPITRE 7 :
Changements de la qualité de vie liée à la santé suivant
une intervention nutritionnelle visant l’adoption de
l’alimentation méditerranéenne : évaluation des
différences de genre chez des hommes et des femmes
présentant des facteurs de risque cardiovasculaire
Vicky Leblanc, Catherine Bégin, Louise Corneau, Sylvie Dodin, Simone Lemieux
Soumis à Journal of Nutrition Education and Behavior, 2015
(soumis le 24 mai 2015)
207
Changes in health-related quality of life following a nutritional intervention
promoting the Mediterranean diet: examination of gender differences in men and
women presenting risk factors for cardiovascular disease
Vicky Leblanc1, Catherine Bégin2, Louise Corneau1, Sylvie Dodin1,3, and Simone
Lemieux1.
1
2
3
2440 Hochelaga Blvd
Phone: (418) 656-2131 ext.: 3637
Fax: (418) 656-5877
Keywords : Gender differences, Mediterranean diet, Self-determined motivation,
Cardiovascular risk, Health-related quality of life.
Abbreviations: HRQOL, Health-related quality of life; CVD, Cardiovascular diseases;
MedDiet, Mediterranean diet; SDT, Self-Determination Theory; MI, Motivational
interviewing; FFQ, Food frequency questionnaire; Medscore, Mediterranean score; SDI,
Self-determination index.
209
RÉSUMÉ
Cette étude avait pour objectif de déterminer les différences de genre dans les changements
liés à la perception de la qualité de vie suivant une intervention nutritionnelle visant
l’adoption de l’alimentation méditerranéenne et basée sur la théorie de l’autodétermination,
et à identifier les facteurs prédisant ces changements chez les hommes et les femmes.
Soixante-quatre hommes et 59 femmes préménopausées à risque de maladies
cardiovasculaires ont pris part à l’intervention de 12 semaines. Le questionnaire SF-36 a été
complété afin d’évaluer la qualité de vie. Aucune différence de genre n’a été observée
quant à la perception de la qualité de vie en réponse à l’intervention et au suivi. Le niveau
de qualité de vie observé à trois mois suivant la fin de l’intervention était significativement
plus élevé qu’au départ chez les hommes et les femmes. Une augmentation de la motivation
autodéterminée spécifique au contexte alimentaire prédisait l’amélioration de la qualité de
vie chez les hommes, alors que chez les femmes, une qualité de vie élevée au départ
prédisait une amélioration moindre. Malgré les changements semblables liés à la qualité de
vie chez les hommes et les femmes, les facteurs prédisant ces changements différeraient
selon le genre.
211
ABSTRACT
Few studies have assessed how improvement in the quality of the diet without a focus on
weight control is related to health-related quality of life (HRQOL). This study aimed at
determining gender differences in changes in perceived HRQOL following a 12-week
nutritional intervention program promoting the Mediterranean diet and based on the SelfDetermination Theory, and to identify factors predicting these changes, in men and women
separately. A sample of 64 men and 59 premenopausal women presenting risk factors for
cardiovascular disease were recruited in the Quebec City metropolitan area, Canada.
HRQOL was assessed with the SF-36 Health Survey. All measurements were performed
before and after the 12-week nutritional intervention program, and then 3 and 6 months
after the end of the nutritional intervention (6 and 9-month follow-up, respectively). No
gender difference was observed for changes in the global HRQOL. A significant time effect
was found for both men and women in the global HRQOL score (P = 0.006), more
specifically with higher scores at 6-month follow-up compared to baseline (P = 0.01).
Increases in eating-related self-determined motivation predicted improvements in global
HRQOL (ß = 0.54, r2 = 0.10, P = 0.03) at 6-month follow-up in men. In women, level of
perceived HRQOL at baseline predicted changes in HRQOL (ß = -0.17, r2 = 0.11, P = 0.03)
at 6-month follow-up. Similar changes in perceived HRQOL were found in men and
women in response to our nutritional intervention, but factors predicting those changes
were not the same in men and women.
213
INTRODUCTION
Evidence supports the undermining effect of chronic diseases and related risk factors on
level of perceived health-related quality of life (HRQOL)
(1, 2)
. In this regard, changing
eating habits is an essential aspect in the prevention of chronic diseases, more particularly
cardiovascular diseases (CVD) (3, 4). The Mediterranean diet (MedDiet) is recognized as one
of the best models of healthy eating providing protection against chronic diseases, such as
CVD
(5, 6)
. According to a cross-sectional study among the Spanish population, adherence
to the MedDiet was associated with higher level of perceived HRQOL
(7)
. Among non-
Mediterranean populations, although health benefits following the adoption of the MedDiet
principles have been reported
(8, 9)
, the impact of adhering to this food pattern on HRQOL
has never been assessed.
In the context of lifestyle interventions, benefit of weight loss on HRQOL changes has been
considerably explored in the literature
(10, 11)
, but to our knowledge, HRQOL changes in
response to dietary modifications, without a focus on weight control, remains unknown.
Moreover, as self-determined motivation has been previously associated with healthier
(12)
dietary intakes
, it could be suggested that nutritional interventions supporting
individuals’ autonomy and competency in their dietary changes, may contribute to
beneficial HRQOL changes. Finally, considering the differences found in the level of
perceived HRQOL between Canadian men and women, with men reporting better HRQOL
than women
(13)
, and also the existence of gender differences in eating habits
eating behaviors
(14, 15)
and
(16)
, assessment of HRQOL changes in response to a nutritional
intervention is relevant but has to be evaluated using a gender approach. The objective of
this study was therefore to determine gender differences in changes in the level of
perceived HRQOL following a 12-week nutritional intervention program promoting the
MedDiet and based on the Self-Determination Theory, and to identify factors predicting
these changes, among Canadian men and women presenting risk factors for CVD.
215
METHODOLOGY
Recruitment of participants and Study design
between 25 and 50 years old, presenting risk factors for cardiovascular disease, and were
recruited through different media advertisements in the Quebec City Metropolitan area,
Canada. Further details related to participants’ recruitment have been reported previously
(17)
. All subjects voluntarily agreed to participate in the research project and written
informed consent was obtained from all men and women prior to their participation in the
study. This study was approved by the Laval University Research Ethics Committee.
The 12-week nutritional program was based on the Self-Determination Theory (SDT) and
used a motivational interviewing (MI) approach. Details about the nutritional intervention
have been reported elsewhere
(17)
but briefly, the study was conducted into small groups
(from January 2010 to November 2012) and the nutritional intervention program included
three group sessions, three individual sessions and four follow-up phone calls with a
registered dietitian (Figure 1). This clinical trial was registered at www.clinicaltrials.gov as
NCT01852721.
intervention program (t = 3 months), and then 3 and 6 months after the end of the
nutritional intervention (6 and 9-month follow-up, respectively).
216
Health-related quality of life
Health-related quality of life (HRQOL) was assessed with the Medical Outcomes Study 36item Short Form (SF-36v2 Standard, Canada (French) Version 2.0) Health Survey (18). This
questionnaire assesses eight different domains. Physical functioning (10 items) measures
limitations in physical activities (e.g., climbing stairs); physical (4 items) and emotional (3
items) role domains assess problems with work or other daily activities because of physical
health or emotional problems; bodily pain (2 items) examines limitations as a result of pain;
vitality (4 items) assesses energy and tiredness; social functioning (2 items) measures the
effect of physical and emotional health on normal social activities; mental health (5 items)
assesses happiness, nervousness and depression; and general health perceptions domain (5
items) assesses personal health and the expectation of changes in health. All domains are
scored on a scale from 0 to 100, where 100 represents the highest level of HRQOL.
Summary scores for a physical and mental components were aggregated from z-score
transformations of the eight domains and transformed to a mean of 50 with a standard
deviation of 10 (19).
Dietary Variables
(20)
dietitian. The FFQ is based on typical foods available in Quebec and contains 91 items and
terms of day, week or month. As previously described
(8)
, a Mediterranean score
(Medscore) was calculated based on the FFQ and allowed to assess the level of adherence
to the Mediterranean food pattern, which can vary between 0 and 44 points. Components of
the Medscore are: grains (whole and refined); fruits (whole and juices); vegetables (whole
and juices); legumes, nuts and seeds; olive oil (including olives); dairy products; fish
(including seafoods); poultry; eggs; sweets and red meat/processed meat. A high
consumption of food groups promoted by the Mediterranean diet (bottom of the pyramid)
(e.g., legumes) contributed to increase the Medscore, whereas a high consumption of food
groups at the top of the Mediterranean pyramid (e.g., red meat) contributed to decrease the
Medscore, as previously described (8).
217
The Regulation of Eating Behaviors Scale
(12)
people close to me insist that I do”), and amotivation (e.g., “I don’t know why I bother”)
(21)
. Each item was measured on a 7-point Likert scale, which allowed calculation of the
eating-related self-determination index (SDI) (22).
Anthropometric Profile
Body weight was measured to the nearest 0.1 kg while height and waist circumference were
measured to the nearest millimeter, according to standardized procedures (23) .
All analyses were performed using SAS statistical software (version 9.2, SAS Institute Inc.,
Cary, NC). Variables are presented in tables as means with standard deviations. MIXED
models for repeated measurements, which allow the inclusion of participants with missing
data at some time points (24), were performed to determine gender, time and gender by time
interaction effects on dependent variables measured. When significant gender by time
interactions were observed, simple effects between times and gender were tested to
determine precisely the location of the main interaction effect. Pairwise differences
between and within gender were further tested with the Tukey-Kramer adjustment. Pearson
correlation allowed testing the associations between changes in key variables under study
and changes in level of perceived HRQOL in men and women. Key variables identified
were the Medscore (indicator of adherence to dietary recommendations promoted through
218
the intervention), eating-related SDI (indicator of motivational mechanism through which
behavioral changes should occur according to our theoretical framework) and body weight
(which has been repeatedly identified as a predictor of HRQOL and which is likely to
decrease in response to a satiating diet such as the MedDiet, even if there is no focus on
weight in the intervention. Then, multiple regression analyses were performed in men and
women separately to determine the respective contribution of variables associated with
changes in perceived HRQOL using a stepwise model procedure. For those analyses, level
of HRQOL at baseline was also entered into the model. For variables not normally
distributed, a transformation was performed but these variables are presented as raw data in
the tables. The probability level for significance used for the interpretation of all statistical
analyses was set at a  level of P  0.05.
RESULTS
Characteristics of men and women at baseline have been reported previously
(17)
. In sum,
men and women were about the same age, but men had higher body weight and waist
circumference and a more deteriorated metabolic profile than women. Moreover, diet
quality as represented by the Medscore was similar in men and women at baseline.
Level of perceived HRQOL in men and women at baseline
Table 1 shows level of perceived HRQOL in men and women at baseline. No significant
gender difference was observed in the global HRQOL score and neither in the eight
different domains nor in the two summary scales (physical component and mental
component).
Changes in perceived HRQOL in men and women, in response to the nutritional
intervention and at follow-up
Changes in perceived HRQOL in men and women are presented in Table 2. No gender
difference was observed for changes in the global HRQOL score and for its eight different
domains as well as for the two summary scales (physical component and mental
219
component). However, a significant time effect was found for both men and women in the
global HRQOL score (P = 0.006), more specifically with significant increases at 3 months
after the end of the nutritional intervention (6-month follow-up) (P = 0.01). Similarly, a
significant time effect was observed in vitality (P = 0.03), with scores significantly higher
at 6-month follow-up compared to baseline (P = 0.05). A significant time effect was also
noted for physical functioning (P = 0.0003), with scores significantly higher at 6-month
follow-up compared to baseline (P = 0.01). As for general health, a trend for a gender by
time interaction was observed (P = 0.08), with scores significantly higher at 6-month
follow-up compared to baseline in both genders but which tend to be larger in men than in
women. As for the two summary scales, a significant time effect was observed in the
mental component only (P = 0.03).
Factors predicting changes in HRQOL at 6-month follow-up, according to gender
As most of the changes in HRQOL reached significance at 6-month follow-up, correlation
analysis was performed between changes in key variables (i.e., changes in the Medscore,
eating-related SDI and body weight) and changes in the global HRQOL score from baseline
to 6-month follow-up (3 months after the end of the intervention). As shown in Table 3,
changes in the Medscore and changes in eating-related SDI were significantly and
positively associated with changes in the global HRQOL score in men only (P = 0.05 and P
= 0.03, respectively). In women, no significant correlation was observed between changes
in key variables and changes in global HRQOL. In both genders, no association was found
between changes in body weight and changes in HRQOL. Regression analyses revealed
that increases in eating-related SDI predicted improvements in global HRQOL (ß = 0.54, r2
= 0.10, P = 0.03) at 6-month follow-up, over and above level of perceived HRQOL at
baseline, in men. In women, only the level of perceived HRQOL at baseline was found to
be a significant predictor of changes in HRQOL in women, i.e., a greater level of perceived
HRQOL at baseline predicted less improvement in global HRQOL (ß = -0.17, r2 = 0.11, P
= 0.03) at 6-month follow-up.
220
DISCUSSION
The aim of our study was to document changes in the level of perceived HRQOL following
a 12-week nutritional intervention program promoting the MedDiet and based on the SelfDetermination Theory, and to identify significant predictors related to these changes, in
men and women distinctively. The intervention led to perception of a better HRQOL
overall and to improvement in different domains of HRQOL, i.e. vitality, physical
functioning and general health, in both men and women. Although men and women showed
similar changes related to perceived HRQOL, we found that factors predicting those
changes were not the same in men and women.
No gender difference was found in perceived level of HRQOL and its different domains at
baseline and neither following the nutritional intervention. Despite similar changes in
HRQOL in both genders, we wanted to determine if factors contributing to those changes
were similar in men and women as gender differences in determinants of HRQOL have
been previously reported in the context of CVD
(25, 26)
. Contrary to other studies
(10, 11)
,
decreases in body weight observed in our study were not associated with improvement in
HRQOL. We found that greater increases in eating-related self-determined motivation, i.e.
internalization of motivational factors related to the adoption of healthy eating, predicted
improvement in overall HRQOL in men. Moreover, despite a positive univariate
association between a greater adherence to the MedDiet and improvement in HRQOL, an
increase in adherence to the MedDiet was not an independent predictor of HRQOL in men.
Our results suggest that the process of change in eating-related self-determined motivation,
rather than dietary changes per se, led to improvement in global HRQOL in men. The SelfDetermination Theory postulates that satisfaction of the needs for autonomy, competency
and relatedness fosters the development of self-determined motivation and favour wellbeing
(21)
. Accordingly, our intervention was based on Self-Determination Theory and
aimed to support individuals’ needs for autonomy, competency and relatedness regarding
the regulation of eating, in order to promote eating-related self-determined motivation,
which has been found to predict improvement in HRQOL in men. Similar findings have
221
been observed regarding self-determined motivation and quality of life in studies promoting
physical activity
(27, 28)
. Our results thus underline the importance to consider motivational
factors in the context of a nutritional approach targeting men. In women, level of HRQOL
at baseline was the only significant predictor related to global HRQOL, with a greater level
of HRQOL at baseline leading to more limited improvement in global HRQOL. These
results suggest that assessment of characteristics related to HRQOL before the beginning of
the intervention seems relevant to determine the potential of improvement in HRQOL
following a nutritional intervention in women. It is important to underline that this
association between baseline HRQOL and changes in HRQOL was not observed in men,
suggesting that a higher level of HRQOL at baseline would not act as a barrier to
improvement in men. Nevertheless, questions remain regarding other factors related to our
nutritional intervention that could not be captured in the present study and that could have
influenced changes observed in HRQOL in women.
Although our findings cannot be extrapolated to the general Canadian population,
originality of this paper arises from the fact that the impact of nutritional interventions on
changes in HRQOL has rarely been assessed without focusing on weight control. Although
positive changes in HRQOL were observed in response to our nutritional intervention and
could represent meaningful information for health professionals, interpretation of our
findings as regard to clinical implications remains limited as no consensus seems to exist
regarding what is a clinically meaningful change in HRQOL
(29)
. Despite the fact that
improvement in CVD risk factors should remain the cornerstone in the development of
nutritional approaches in the context of CVD prevention, HRQOL should be assessed as it
can provide additional health-related information about the clients. Although it is usually
suggested that changes in dietary habits can favor an improvement in HRQOL, it also has
to be kept in mind that an improvement in HRQOL can in turn favour a better adherence to
dietary recommendations, as previously reported (30, 31).
In conclusion, despite similar beneficial changes in perceived HRQOL in men and women
in response to our nutritional intervention program, gender differences were found in
factors predicting those changes. These results suggest that a gender approach should be
222
used when aiming at improving HRQOL through intervention modalities.
ACKNOWLEDGEMENTS
AUTHORSHIP
design of the study as well as to the interpretation of data; L.C. and S.D. contributed to the
conception and design of the study; S.L. (corresponding author) was responsible for the
conception and design of the study and contributed to the interpretation of data. All of the
authors have read and approved the final version of the manuscript submitted for
publication.
223
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Table 1. Characteristics of health-related quality of life in men and women at baseline
Physical functioning
Role functioning: Physical
Bodily pain
General health
Vitality
Social functioning
Role functioning: Emotional
Mental health
Global health-related quality of life score
Physical component scale
Mental component scale
SD : Standard deviation.
228
Men
Baseline
n = 64
91.7
86.8
78.9
70.2
58.9
85.9
82.4
68.1
77.9
52.6
44.9
SD
9.8
17.2
18.6
16.5
14.6
17.3
21.6
9.7
10.6
6.0
7.8
Women
Baseline
SD
n = 59
89.7
11.2
85.7
18.4
76.1
21.9
72.6
16.6
57.7
12.8
81.4
19.3
83.1
19.4
67.5
11.5
76.7
11.0
52.1
7.7
44.4
7.8
Table 2. Changes in health-related quality of life in men and women in response to the 12-week nutritional intervention program (T=3
months), and at 6 and 9-month follow-up
Men
Variables
Physical functioning
Baseline
T=3 months
T=6 months
T=9 months
Role functioning: Physical
Baseline
T=3 months
T=6 months
T=9 months
Bodily pain
Baseline
T=3 months
T=6 months
T=9 months
General health
Baseline
T=3 months
T=6 months
T=9 months
Mean
91.7
93.1
94.1 *
94.7 *
86.8
84.5
88.5
86.0
78.9
80.5
81.4
82.4
70.2
74.6 *
75.7 *
74.5
Women
SD
9.8
9.9
7.5
5.9
17.2
21.5
18.0
19.7
18.6
22.0
18.0
20.1
16.5
18.2
16.9
18.4
Mean
89.7
90.2
92.5 *
91.4 *
85.7
84.4
86.1
81.7
76.1
79.2
79.9
77.2
72.6
73.2 *
72.6 *
73.8
Gender differences Time effect
SD
Gender x time
interaction
P
P
P
0.19
< 0.0001
0.88
0.47
0.07
0.86
0.29
0.46
0.82
0.77
0.01
0.08
11.2
13.5
11.5
15.9
18.4
17.7
19.1
21.4
21.9
21.4
18.3
21.5
16.6
16.0
15.2
16.3
229
Table 2. Changes in health-related quality of life in men and women in response to the 12-week nutritional intervention
program (T=3 months), and at the 6 and 9-month follow-up (continued)
Men
Women
Gender x time
interaction
Variables
Mean
SD
Mean
SD
P
P
P
Vitality
Baseline
T=3 months
T=6 months
T=9 months
Social functioning
Baseline
T=3 months
T=6 months
T=9 months
Role functioning: Emotional
Baseline
T=3 months
T=6 months
T=9 months
Mental health
Baseline
T=3 months
T=6 months
T=9 months
230
58.9
61.1
63.4 *
62.0
85.9
86.8
89.3
88.7
82.4
83.3
85.5
83.1
68.1
69.0
70.2
70.3
14.6
13.2
12.0
14.5
17.3
19.7
14.9
17.4
21.6
21.3
21.0
21.7
9.7
10.2
9.8
11.1
57.7
60.7
59.2 *
58.0
81.4
84.9
86.4
83.2
83.1
84.0
84.3
79.2
67.5
67.6
69.1
65.0
0.32
0.03
0.46
0.24
0.07
0.80
0.64
0.16
0.90
0.24
0.29
0.13
12.8
13.5
13.6
14.5
19.3
20.1
18.0
20.2
19.4
20.4
18.2
24.1
11.5
12.4
11.1
14.0
Table 2. Changes in health-related quality of life in men and women in response to the 12-week nutritional intervention
program (T=3 months), and at the 6 and 9-month follow-up (continued)
Men
Women
Gender x time
interaction
Variables
Mean
SD
Mean
SD
P
P
P
0.36
0.01
0.74
Global quality of life score
Baseline
77.9
10.6
76.7
11.0
T=3 months
79.0
12.2
78.1
12.9
T=6 months
81.0 *
11.6
78.8 *
11.4
T=9 months
80.2
12.0
76.2
14.6
Physical component scale
0.60
0.12
0.91
Baseline
52.6
6.0
52.1
7.7
T=3 months
53.3
7.3
52.6
7.2
T=6 months
54.0
5.3
53.1
7.2
T=9 months
53.9
6.0
52.9
8.4
Mental component scale
0.39
0.03
0.67
Baseline
44.9
7.8
44.4
7.8
T=3 months
45.6
7.7
45.3
8.0
T=6 months
46.6
7.6
45.6
7.6
T=9 months
46.0 ¶
8.6
43.3 ¶
9.5
Proc Mixed procedure performed with n= 63, 57, 49 and 44 men and n= 59, 49, 44 and 44 women, at baseline (t= 0), 3, 6
and 9 months respectively. T=3 months : end of the intervention; T=6 months : 3 months after the end of the intervention;
T=9 months : 6 months after the end of the intervention.
SD: Standard déviation.
* Mean value significantly different than baseline value according to gender at P ≤ 0.05.
¶ Trend for a significant decrease compared to the mean value at 6 months (3-month post intervention) at P = 0.08.
231
Table 3. Associations between changes in the Medscore, eating-related self-determined motivation and body weight and changes in
global HRQOL in men and women from baseline to 6-month follow-up*
Δ Medscore
Δ Eating-related SDI
Δ Body weight
r
P
r
P
r
P
Δ Global HRQOL in men
0.28
0.05
0.31
0.03
-0.007
0.96
Δ Global HRQOL in women
-0.10
0.50
0.08
0.63
0.20
0.18
* 6-month follow-up : 3 months after the end of the intervention.
Pearson correlation performed with n= 49 men and n= 44 women.
Δ: Changes from baseline (t=0) to 3-month post intervention.
232
CHAPITRE 8 :
Conclusion générale
233
Malgré une diminution du taux de mortalité lié aux MCV dans la population canadienne
dans les dernières décennies (Agence de la santé publique du Canada, 2015), plusieurs
individus sont encore touchés par ces maladies, ce qui soutient le besoin de continuer à
déployer des efforts en prévention. L’adoption de saines habitudes alimentaires constitue
un aspect primordial dans la prévention des MCV et l’alimentation méditerranéenne est
reconnue comme une référence à cet égard, notamment en raison de ses bienfaits sur la
santé cardiovasculaire. Dans un contexte de changement des habitudes et comportements
alimentaires, la motivation est reconnue comme un facteur déterminant, mais peu d’études
ont évalué l’importance de la qualité de la motivation dans les changements alimentaires
jusqu’à maintenant. À cet égard, la théorie de l’autodétermination soutient que le maintien
d’un comportement est le résultat du niveau de motivation autodéterminée d’un individu
(Deci & Ryan, 1985; Ryan & Deci, 2000). Des études ont d’ailleurs démontré qu’un
comportement régulé via une motivation autodéterminée prédispose au maintien de saines
habitudes alimentaires à long terme (Pelletier et al., 2004; Williams et al., 1996). D’autre
part, des différences relatives au genre sont rapportées à l’égard des habitudes et
comportements alimentaires, ce qui supporte la nécessité de considérer les hommes et les
femmes distinctement dans le contexte d’une intervention nutritionnelle.
Considérant le potentiel de l’alimentation méditerranéenne dans la prévention de MCV,
mais également la difficulté pour certains individus à adhérer aux recommandations
alimentaires, il s’avérait impératif d’examiner les différences entre les hommes et les
femmes quant à l’impact de facteurs liés à la motivation dans la réponse à une intervention
nutritionnelle visant l’adoption de l’alimentation méditerranéenne. Dans le cadre de cette
thèse, notre principal objectif visait à déterminer les différences entre les hommes et les
femmes dans leur réponse à un programme d’éducation en nutrition de 12 semaines visant
l’adoption d’une alimentation de type méditerranéen et basé sur la théorie de
l’autodétermination,
plus
spécifiquement
dans
les
changements
alimentaires,
anthropométriques, métaboliques et liés à la qualité de vie. Globalement, nos travaux ont
démontré que le programme d’éducation en nutrition basé sur une approche motivationnelle
a contribué à l’amélioration des apports alimentaires et à la diminution de facteurs de risque
cardiovasculaire, plus particulièrement chez les hommes. De plus, le fait que les niveaux
235
d’activité physique soient demeurés stables tout au long de l’intervention à la fois chez les
hommes et les femmes permet de confirmer l’impact positif de notre intervention
nutritionnelle sur la diminution des facteurs de risque cardiovasculaire, via une
amélioration des apports alimentaires.
Dans un premier temps, nos résultats ont permis de caractériser les hommes et les femmes
selon leur profil motivationnel, ainsi que leurs apports et comportements alimentaires avant
le début de l’intervention nutritionnelle. Tel que présumé, les femmes démontraient un
niveau de motivation autodéterminée plus élevé que les hommes, sans compter que leur
motivation était associée à une alimentation plus saine et à un profil anthropométrique plus
favorable, ce qui n’était pas le cas chez les hommes. Nos résultats observés chez les
femmes concordent avec les travaux de Pelletier et al. rapportant qu’une motivation
autodéterminée plus élevée est associée à des apports et comportements alimentaires
prédisposant à une régulation plus saine du poids chez les femmes (Pelletier et al., 2004).
Le fait de constater que les hommes et les femmes ne présentent pas le même niveau de
motivation autodéterminée au départ suggère que leurs facteurs de motivation à l’égard de
l’alimentation ne sont pas les mêmes, ce qui confirme la pertinence d’évaluer la qualité de
la motivation et de considérer les différentes caractéristiques des individus, dont le genre,
dès le début d’une démarche nutritionnelle, afin de mieux répondre à leurs besoins.
À notre connaissance, aucune étude ne semble avoir examiné la relation entre la motivation
autodéterminée à l’égard de l’alimentation et la qualité de l’alimentation selon le genre
jusqu’à maintenant, ce qui ne permet pas de comparer nos résultats à la littérature.
Cependant, on peut supposer que l’implication plus importante des femmes dans la
préparation des repas rapportée dans notre étude pourrait en partie expliquer le niveau de
motivation autodéterminée plus élevé chez ces dernières. En effet, les femmes demeurent
les personnes principalement en charge de la préparation des repas pour la famille avec
environ le double du temps consacré à cette tâche en comparaison avec les hommes (Blake
et al., 2009; Murcott, 2000). Certains auteurs suggèrent toutefois une diminution de l’écart
entre les hommes et les femmes quant au rôle attribué pour la préparation des repas, avec
20% des couples mariés affirmant partager la responsabilité de cuisiner pour la famille
236
(Blake et al., 2009; Murcott, 2000). Ces données amènent à penser que les rôles et
responsabilités attribués aux hommes et aux femmes dans la société sont en processus de
changement, et que le portrait quant aux facteurs de motivation pourrait aussi changer
advenant le cas où l’implication des hommes augmentait dans le contexte de l’alimentation.
Nos travaux ont démontré que les hommes et les femmes augmentaient de façon similaire
leur adhésion à l’alimentation méditerranéenne en réponse à l’intervention nutritionnelle,
mais avec une amélioration plus prononcée de certaines composantes alimentaires, ce qui
confirme notre hypothèse de départ. Des limites semblables ont été observées chez les
hommes et les femmes face au maintien des changements alimentaires après l’intervention
nutritionnelle de 12 semaines. En parallèle, le programme d’éducation en nutrition qui
visait à promouvoir la motivation autodéterminée a mené à une amélioration globale plus
importante de la motivation autodéterminée chez les hommes que chez les femmes, avec un
retour vers les valeurs de départ au cours de la période de suivi chez les hommes et les
femmes. Par ailleurs, dans le cadre de notre intervention, une augmentation de la
motivation autodéterminée était associée à une meilleure adhésion à l’alimentation
méditerranéenne chez les hommes seulement.
Le fait que les femmes présentaient une alimentation se rapprochant davantage des
principes de l’alimentation méditerranéenne avant l’intervention peut expliquer en partie
l’amélioration plus limitée de certains changements alimentaires spécifiques en
comparaison avec les hommes, en réponse à l’intervention. Nos observations concordent
avec les travaux de Zazpe et al. qui ont démontré un meilleur succès de leur intervention en
termes de changements alimentaires auprès des hommes qu’auprès des femmes (Zazpe et
al., 2010). Par contre, la présence de différences entre les hommes et les femmes demeure
malgré l’ajustement pour les valeurs de départ, ce qui indique que d’autres facteurs liés au
genre sont impliqués dans le potentiel des changements alimentaires en réponse à
l’intervention.
237
Considérant que le programme d’éducation en nutrition a mené à une augmentation plus
importante de la motivation autodéterminée chez les hommes que chez les femmes, et
qu’une association entre les changements de motivation et les changements dans l’adhésion
à l’alimentation méditerranéenne a été observée chez les hommes seulement, on peut
émettre l’hypothèse selon laquelle des aspects de l’intervention ont été plus appropriés afin
d’améliorer la qualité de l’alimentation chez les hommes. D’abord, l’intervention était
basée sur une approche motivationnelle visant essentiellement à soutenir la satisfaction des
besoins d’autonomie, de compétence et du sentiment d’attachement des hommes et des
femmes. En ce sens, certaines études évoquent l’importance pour les hommes de se sentir
autonomes dans leur démarche dans un contexte de prévention de MCV (Addis & Mahalik,
2003; Mroz et al., 2011). D’autre part, il est possible que les hommes aient davantage
bénéficié de certains outils utilisés via l’approche motivationnelle dans leur processus de
changement. En effet, des évidences soutiennent que les hommes seraient plus ambivalents
que les femmes à l’égard des choix alimentaires sains (Povey et al., 2001; Sparks et al.,
2001) et seraient plus nombreux à ne pas savoir comment prendre action afin de maintenir
un bon état de santé (Haidinger et al., 2012). Dans le contexte de l’intervention, la balance
décisionnelle, soit un outil visant à résoudre l’ambivalence face au changement par
l’exploration des avantages et désavantages perçus au changement, constituait un outil
utilisé lors de la première rencontre individuelle. La balance décisionnelle pouvait être
réutlisée aux rencontres subséquentes selon les besoins spécifiques des individus, par
exemple en présence d’ambivalence. Les hommes et les femmes devaient également
compléter un plan d’action afin de formuler en détails leurs objectifs de changements
alimentaires ainsi que les stratégies favorables potentielles pour y parvenir, soit un autre
outil du programme d’intervention. Le plan d’action fut utilisé tout au long de
l’intervention, avec le soutien nécessaire de la part de la nutritionniste. En définitive, il est
probable que l’approche en soi ainsi que les outils d’intervention utilisés se soient avérés
plus appropriés pour les hommes et favorables aux changements alimentaires.
L’amélioration plus limitée de la motivation autodéterminée chez les femmes s’explique
possiblement en raison de leur niveau de motivation plus élevé au départ. Il est ainsi
probable que l’impact de l’approche motivationnelle visant à soutenir la satisfaction des
238
besoins psychologiques ait été plus limité chez les femmes, ce qui ne peut toutefois pas être
affirmé avec certitude. Afin de mieux comprendre les changements de motivation observés
chez les hommes et les femmes, il aurait été intéressant de pouvoir évaluer la satisfaction
des besoins d’autonomie, de compétence et du sentiment d’attachement non seulement
avant l’intervention, mais également suite à l’intervention. Pour ce faire, il serait approprié
de développer un questionnaire permettant d’évaluer la satisfaction de ces besoins dans le
contexte spécifique de l’alimentation. La disponibilité d’un tel questionnaire aurait permis
d’interpréter plus clairement l’impact de l’intervention sur les changements de motivation
et les changements alimentaires.
Nos résultats permettent de confirmer partiellement notre hypothèse de départ qui suggérait
que les hommes et les femmes qui amélioreraient leur niveau de motivation autodéterminée
augmenteraient davantage leur niveau d’adhésion à l’alimentation méditerranéenne. Il
demeure difficile d’expliquer l’absence d’association chez les femmes à cet égard, mais il
semble que le niveau de motivation autodéterminée plus élevé au départ ne permette pas
d’expliquer ces résultats. Néanmoins, il est possible que les facteurs de motivation aient été
plus conscients et plus clairement identifiés dès le départ chez les femmes, ce qui pourrait
expliquer la présence d’une amélioration de leur adhésion à l’alimentation méditerranéenne
en réponse à l’intervention, indépendamment des changements de motivation. En appui à
ces propos, nos travaux ont permis de constater que les femmes ayant un niveau de
motivation autodéterminée plus élevé au départ présentaient une meilleure adhésion aux
principes de l’alimentation méditerranéenne à la fin de l’intervention nutritionnelle. À cet
égard, certaines stratégies post-motivationnelles visant à faciliter le passage de l’intention à
l’action des personnes déjà motivées à agir, par exemple l’élaboration d’un plan d’action,
sont proposées dans la littérature (Godin, 2012), ce qui soutient l’idée que les femmes
peuvent tout de même avoir tiré profit du programme d’éducation en nutrition pour
modifier leurs habitudes alimentaires. De plus, il est à noter que certains facteurs
modérateurs pourraient influencer l’efficacité de l’activation des intentions, notamment les
habitudes (Godin, 2012). D’autre part, le contexte familial pourrait s’avérer un autre facteur
important ayant pu limiter l’impact des changements de motivation autodéterminée dans la
mise en action, c’est-à-dire dans l’adoption de changements alimentaires sains. Plus
239
spécifiquement, selon certains auteurs les femmes sont plus susceptibles de sacrifier leurs
habitudes alimentaires afin de satisfaire les préférences alimentaires de leur famille
(Sarkadi & Rosenqvist, 2002). De plus, des travaux menés dans le contexte de la prise en
charge du diabète suggèrent que les femmes soutiennent leur conjoint dans les changements
alimentaires effectués alors que les hommes démontrent un soutien moindre envers leur
conjointe à cet égard (Wong et al., 2005; Sandberg et al., 2006). Enfin, les femmes
déplorent davantage le manque de soutien et la présence de pression de la part de la famille
concernant l’alimentation. Ces données amènent à penser que le contexte familial pourrait
exercer une influence plus importante sur les habitudes alimentaires des femmes que des
hommes. Dans le cadre de notre étude, plusieurs facteurs peuvent être mis en cause et avoir
brouillé l’association entre les changements de motivation autodéterminée et les
changements dans l’adhésion à l’alimentation méditerranéenne chez les femmes,
notamment le contexte familial. Considérant que les femmes de notre étude étaient
davantage en charge de l’achat et de la préparation des aliments comparativement aux
hommes, il est possible que ces dernières aient accordé une importance plus grande que les
hommes à l’acceptabilité de l’alimentation méditerranéenne par les autres membres de la
famille, et que cela ait pu contrecarrer les effets des changements de motivation dans
l’amélioration de l’alimentation et possiblement limiter l’ampleur des changements
alimentaires notés chez les femmes. Il serait intéressant dans des études futures d’examiner
plus spécifiquement l’impact de diverses variables modératrices et médiatrices, par
exemple le concept de l’habitude et le contexte familial, afin de clarifier si certains facteurs
permettent d’expliquer qu’une augmentation de la motivation autodéterminée ne se traduit
pas directement par une amélioration de la qualité de l’alimentation chez les femmes.
Nos observations permettent de mettre en lumière les difficultés éprouvées par les hommes
et les femmes à maintenir les changements alimentaires une fois l’intervention terminée.
Plusieurs éléments peuvent être mis en cause afin d’expliquer le retour vers les valeurs de
départ de certaines composantes de l’alimentation méditerranéenne. Il est possible que
certains changements alimentaires aient été difficiles à maintenir en raison du fait qu’ils
consistaient soit à intégrer des aliments qui étaient peu familiers, soit à diminuer la
consommation d’aliments qui occupaient une place importante dans leur alimentation au
240
départ. D’autre part, la transition entre la fin du programme d’éducation en nutrition
intensif de 12 semaines et la période de suivi, où aucun contact supplémentaire n’avait lieu
entre l’intervenant et les participants, a pu être perçue comme trop drastique et aussi avoir
contribué à limiter le maintien des changements alimentaires. Outre ces aspects d’ordre
individuel, certains facteurs environnementaux propres au contexte québécois peuvent avoir
influencé la capacité des hommes et des femmes à maintenir l’adhésion à l’alimentation
méditerranéenne, comme par exemple la disponibilité et l’accessibilité plus limitées
d’aliments fréquemment consommés traditionnellement dans les pays méditerranéens.
Quoiqu’il en soit, à la fin de la période de suivi, le niveau d’adhésion à l’alimentation
méditerranéenne était plus élevé qu’au départ chez les hommes, ce qui permet de confirmer
l’impact positif de l’intervention nutritionnelle sur l’amélioration de la qualité de
l’alimentation, plus particulièrement chez les hommes.
D’ailleurs, les changements anthropométriques et métaboliques observés permettent
d’appuyer les effets plus importants de l’intervention nutritionnelle dans l’adoption de
l’alimentation méditerranéenne chez les hommes. Cependant, aucune différence liée au
genre n’a été notée en ce qui a trait au changement dans la perception du niveau de qualité
de vie relative à la santé, ce qui confirme partiellement notre hypothèse de départ, qui
suggérait que les hommes bénéficieraient davantage du programme d’éducation en nutrition
visant l’adoption d’une alimentation de type méditerranéen par une amélioration plus
importante de leur profil métabolique et de leur niveau de qualité de vie. Nos résultats
amènent à penser que les changements physiologiques observés découlent des effets
rassasiants attribués à l’alimentation méditerranéenne (Schroder et al., 2004), mais aussi
possiblement des changements notés dans les comportements alimentaires des hommes
puisque ceux ayant le plus diminué leur niveau de désinhibition avaient tendance à avoir
davantage diminué leur poids corporel. Enfin, sans pouvoir définir leur contribution exacte,
il est probable qu’une partie de nos résultats s’expliquent par la présence de différences
sexuelles. Plus précisément, des études soutiennent qu’en réponse à des changements dans
les habitudes de vie, les hommes sont plus susceptibles que les femmes de diminuer leur
circonférence de la taille, via une mobilisation préférentielle du tissu adipeux abdominal
(Lemieux et al., 1993; Smith & Zachwieja, 1999). Par ailleurs, il est bien établi dans la
241
littérature qu’une diminution du tissu adipeux abdominal contribue à l’amélioration de
certains facteurs de risque liés aux MCV (Bastien et al., 2014). Ces travaux concordent
avec nos résultats observés chez les hommes, ce qui souligne l’importance de considérer le
sexe, au-delà des différences relatives au genre, dans le contexte de la régulation des
apports alimentaires et de l’impact potentiel d’une intervention nutritionnelle sur la santé
cardiovasculaire.
Concernant plus spécifiquement les hommes, plusieurs évidences indiquent que ces
derniers constituent une population difficile à rejoindre dans le contexte d’une démarche
visant l’amélioration des comportements et habitudes alimentaires, et ce, malgré le fait
qu’ils présentent une prévalence de MCV plus élevée que les femmes (Taylor et al., 2013).
La littérature soutient la pertinence de s’intéresser plus particulièrement aux intérêts des
hommes dans le but de développer des interventions nutritionnelles adaptées à leurs
besoins. Dans cet ordre d’idées, nos résultats permettent de confirmer la faisabilité pour les
hommes d’adhérer aux principes de l’alimentation méditerranéenne dans le contexte
québécois. De telles données ont été précédemment rapportées chez les femmes (Goulet et
al., 2003), mais la faisabilité d’adopter l’alimentation méditerranéenne chez les hommes
québécois demeurait non documentée jusqu’maintenant. De plus, le recours à l’entretien
motivationnel dans le contexte d’une intervention nutritionnelle développée selon les
construits de la théorie de l’autodétermination semble une approche clinique prometteuse,
plus particulièrement auprès des hommes. Cette hypothèse est d’ailleurs soutenue par les
travaux de Maindal et al. rapportant qu’un programme d’intervention nutritionnelle mené
auprès de personnes diabétiques et visant à favoriser la motivation autodéterminée, le
sentiment de compétence et l’expérimentation à travers des rencontres individuelles et de
groupe, s’avère plus bénéfique aux hommes qu’aux femmes (Maindal et al., 2011).
En termes de perspectives futures de recherche, nos travaux soulignent la pertinence de
s’intéresser plus particulièrement au type, mais également à la durée du soutien offert au
cours d’une intervention nutritionnelle visant des changements alimentaires durables à la
fois chez les hommes et chez les femmes. La théorie de l’autodétermination postule que le
succès d’un changement de comportement ainsi que le maintien du comportement à long
242
terme est prédit en partie par la qualité de l’environnement social d’une personne (Deci et
al., 1994). À ce sujet, certaines études indiquent que les individus démontrent une
régulation davantage autodéterminée lorsque les personnes importantes dans leur
environnement social, par exemple les parents, le conjoint ou les amis, soutiennent la
satisfaction de leurs besoins psychologiques fondamentaux (Gorin et al., 2014; Pelletier &
Dion, 2007; Williams et al., 2004). D’ailleurs, certaines évidences indiquent que le soutien
à l’autonomie provenant d’une personne significative pourrait augmenter l’engagement au
changement et les probabilités de rester impliqué dans un processus de changement de
comportement (Gorin et al., 2014; Miller et al., 1995). Une étude de Steptoe et al. abonde
dans le même sens en indiquant que le soutien social perçu de la part de la famille, d’amis
et de collègues avant une intervention prédit l’augmentation de la consommation de fruits
et de légumes lors du suivi à 12 mois (Steptoe et al., 2004). Dans le cadre d’études futures,
il pourrait s’avérer profitable d’impliquer les personnes significatives dans la démarche
nutritionnelle dès le départ, en plus d’offrir le soutien d’une nutritionniste. Cette stratégie
permettrait d’outiller la personne significative afin que celle-ci soit en mesure de continuer
à épauler l’individu une fois l’intervention terminée. Cette forme de soutien pourrait
également être envisagée en pratique clinique dans l’optique de changements durables
requérant peu de ressources professionnelles. D’autre part, l’impact d’une intervention
moins intense mais prolongée, les effets d’une transition plus progressive entre la fin de
l’intervention et la période de suivi, et le potentiel de la création d’un réseau de soutien
social en lien avec l’adoption d’une saine alimentation et la prévention de la santé
cardiovasculaire mériteraient aussi d’être explorés davantage, et selon le genre.
Au-delà du soutien offert à l’individu, d’autres aspects sont susceptibles de favoriser le
maintien des changements alimentaires et l’amélioration de la santé chez les hommes et les
femmes. Afin d’améliorer l’efficacité des interventions nutritionnelles, dans le contexte de
société actuelle où les ressources sont limitées, il est primordial de raffiner nos cibles
d’intervention auprès des individus. Pour ce faire, il serait pertinent dans un premier temps
de recueillir des données de nature qualitative afin de mieux identifier les barrières et
facteurs facilitants liés aux changements alimentaires, plus particulièrement pour le
maintien à long terme, et selon le genre. Par ailleurs, on peut penser que les interventions
243
globales, c’est-à-dire celles qui permettent de modifier plusieurs habitudes de vie au cours
d’une même intervention, par exemple en intégrant la composante d’activité physique aux
changements alimentaires, pourraient accroître l’impact sur la santé. De plus, certaines
études suggèrent de favoriser les interventions de groupe puisqu’elles permettent d’offrir un
soutien adéquat et exigent moins de ressources financières et humaines qu’un suivi
individuel (Endevelt et al., 2015; Yank et al., 2013). Enfin, les diverses technologies telles
que le Web et le téléphone cellulaire devraient être davantage exploitées puisqu’elles
constituent des outils permettant d’offrir un soutien prolongé aux individus à moindre coût,
et qui peuvent également optimiser les communications entre les membres d’un même
réseau social. D’un autre côté, puisque les déterminants d’une saine alimentation relèvent
d’une part de l’individu, mais aussi du contexte de vie dans lequel celui-ci évolue, tout
porte à croire que des efforts doivent continuer à être investis en santé publique afin
d’améliorer la disponibilité et l’accessibilité à des aliments sains, pour ainsi optimiser les
impacts des interventions nutritionnelles et favoriser le maintien de leurs effets à long
terme.
Certaines implications pour la pratique clinique en nutrition découlent des travaux
présentés dans cette thèse. Nos travaux ont permis de démontrer qu’une intervention
nutritionnelle non restrictive, non axée sur la perte de poids et adaptée aux besoins et
préférences des hommes et des femmes engendre des impacts positifs sur la qualité de
l’alimentation et certains facteurs de risque associés aux MCV. Toutefois, nos résultats ont
démontré que les hommes et les femmes répondaient différemment au programme
d’éducation en nutrition de 12 semaines, ce qui soutient la pertinence de considérer le genre
et le sexe dans le développement des interventions nutritionnelles. Dans un autre ordre
d’idées, afin de soutenir les hommes et les femmes dans l’adoption de saines habitudes
alimentaires à long terme, il semble souhaitable d’opter pour des approches nutritionnelles
qui accordent non seulement une importance à l’amélioration des apports alimentaires, mais
également à la régulation de comportements alimentaires sains et au niveau de qualité de
vie relative à la santé. Le choix d’une intervention nutritionnelle soutenant la motivation
autodéterminée et visant l’adoption des principes de l’alimentation méditerranéenne semble
concorder avec cette vision.
244
Une des principales forces se rapportant à l’intervention nutritionnelle développée pour ce
projet de recherche relève de la flexibilité de l’approche motivationnelle. En effet, une telle
approche possède un important potentiel de spécificité permettant de tenir compte des
besoins, habiletés et ressources des hommes et des femmes et a permis de déterminer des
objectifs de changements alimentaires qui tenaient compte de leur contexte social et de leur
niveau socioéconomique. Cette approche individualisée permet donc de rejoindre et
d’intervenir auprès d’une grande partie de la population. Il serait néanmoins intéressant
dans une étude future d’évaluer l’impact d’une telle approche sur le risque cardiovasculaire
chez des hommes et des femmes présentant des caractéristiques différentes, par exemple un
niveau socioéconomique plus faible ou une santé métabolique plus détériorée.
Certaines limites en lien avec l’interprétation des travaux présentés dans cette thèse
méritent d’être considérées, notamment le fait que l’échantillon n’était pas représentatif de
la population générale. En effet, les hommes et les femmes recrutés dans ce projet de
recherche présentaient des habitudes alimentaires concordant davantage avec les
recommandations du Guide alimentaire canadien et démontraient nécessairement un
minimum de motivation au début de l’intervention. Par ailleurs, il importe de garder en tête
que dans le cadre de cette étude, le concept du genre a été utilisé de manière dichotomique
afin d’améliorer la compréhension de son impact dans un contexte d’intervention
nutritionnelle. Cependant, il est évident que le portrait des hommes et des femmes à l’égard
de leurs rôles, responsabilités et croyances dans le contexte de l’alimentation n’est pas
complètement dissociable l’un de l’autre, et donc qu’en réalité le concept du genre devrait
plutôt être considéré selon un continuum (Institute of Gender and Health, 2012).
En définitive, cette thèse a permis de mettre en lumière les différences entre les hommes et
les femmes quant à l’impact d’une intervention nutritionnelle basée sur une approche
motivationnelle. Plus précisément, nos travaux ont permis de démontrer que le programme
d’éducation
en
nutrition
de
12
semaines
visant
l’adoption
de
l’alimentation
méditerranéenne et ayant recours à l’entretien motivationnel a engendré des changements
plus prononcés à long terme dans les habitudes alimentaires chez les hommes que chez les
femmes, contribuant ainsi à une amélioration plus importante du profil métabolique chez
les hommes.
245
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266
ANNEXE :
Score méditerranéen
267
Score méditerranéen
Pointage
0
1
2
3
4
Produits céréaliers à
grains entiers 1
< 1 portion/jour
1-2 portions/jour
3-4 portions/jour
5-6 portions/jour
≥ 7 portions/jour
Légumes 2
< 1 portion/jour
1 portion/jour
2 portions/jour
3 portions/jour
≥ 4 portions/jour
Fruits 3
< 1 portion/jour
1 portion/jour
2 portions/jour
3 portions/jour
≥ 4 portions/jour
Légumineuses, noix et
graines 4
< 0,5 portion/jour
0,5 portion/jour
1 portion/jour
2 portions/jour
> 2 portions/jour
Huile d’olive, olives et
margarine à base d’huile
d’olive 5
< 1 fois/jour
1 fois/jour
2 fois/jour
3 fois/jour
≥ 4 fois/jour
Lait et produits laitiers 6
< 1 portion/jour ou
> 4 portions/jour
4 portions/jour
1 portion/jour
2-3 portions/jour
Poissons et fruits de mer
(autres que panés) 7
Jamais
< 1 portion/sem
1 portion/sem
2 portions/sem
≥ 3 portions/sem
Volailles (autres que
panées) 7
Jamais
< 1 portion/sem
1 portion/sem ou
≥ 4 portions/sem
2 portions/sem
3 portions/sem
Oeufs
≥ 7/sem
Sucreries 8
≥ 7 fois/sem
5-6 fois/sem
3-4 fois/sem
1-2 fois/sem
< 1/sem
Viandes rouges, abats
et charcuteries 7
≥ 7 portions/sem
5-6 portions/sem
3-4 portions/sem
1-2 portions/sem
< 1 fois/sem
5-6/sem
0-4/sem
Pour les produits céréaliers, une portion équivaut à une tranche de pain, ½ tasse de pâtes alimentaires, de riz ou de
couscous, et 30 g de céréales. Le mode alimentaire méditerranéen favorise les grains entiers. Par conséquent, un
maximum d’un point est attribué à la consommation de produits céréaliers raffinés (par exemple, pain blanc ou
céréales raffinées).
1
Pour les légumes, une portion équivaut à ½ tasse ou un légume de taille moyenne. Le mode alimentaire
méditerranéen favorise les légumes frais. Par conséquent, un maximum d’un point est attribué à la consommation
d’une portion de jus de légume (½ tasse).
2
Pour les fruits, une portion équivaut à ½ tasse ou un fruit de taille moyenne. Le mode alimentaire méditerranéen
favorise les fruits frais. Par conséquent, un maximum d’un point est attribué à la consommation d’une portion de
jus de fruit (½ tasse).
3
Pour les légumineuses, noix et graines, une portion équivaut à ½ tasse de légumineuses, ¼ tasse de noix ou
graines et à 100 g de tofu.
4
Pour l’huile d’olive, un point est attribué pour chaque usage de cette huile. Le mode alimentaire méditerranéen
favorise l’utilisation de l’huile d’olive comme principale source de matières grasses. Par conséquent, un maximum
d’un point est attribué à la consommation d’huile de canola ou de margarine faite à partir de cette huile.
5
Pour le lait et les produits laitiers, une portion équivaut à une tasse de lait ou de boisson de soya enrichie, 50 g de
fromage, ou 175 g de yogourt.
6
7
Pour les viandes rouges, abats et charcuteries, les volailles et le poisson, une portion équivaut à 75 g.
Pour les sucreries, une portion équivaut, par exemple, à 1/12 de gâteau, 1/6 de tarte ou une barre de chocolat de
format habituel.
8
269

Adoption de l`alimentation méditerranéenne basée sur la théorie de

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