Patient Preference and Adherence (Nov 2016)
Body image discrepancy and subjective norm as mediators and moderators of the relationship between body mass index and quality of life
Abstract
Benoit Pétré,1 André J Scheen,2 Olivier Ziegler,3 Anne-Françoise Donneau,1 Nadia Dardenne,1 Eddy Husson,1 Adelin Albert,1 Michèle Guillaume1 1Department of Public Health, University of Liège, Liège, Belgium; 2Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, CHU Sart Tilman, University of Liège, Liège, Belgium; 3Department of Diabetes, Metabolic Diseases and Nutrition, Nancy University Hospital, Nancy, France Background and objective: Despite the strength and consistency of the relationship between body mass index (BMI) and quality of life (QoL), a reduction in BMI does not necessarily lead to an improvement in QoL. Between-subject variability indicates the presence of mediators and moderators in the BMI–QoL association. This study aimed to examine the roles of body image discrepancy (BID) and subjective norm (SN) as potential mediators and moderators. Subjects and methods: In 2012, 3,016 volunteers (aged ≥18 years) participated in a community-based survey conducted in the French-speaking region of Belgium. Participation was enhanced using a large multimedia campaign (which was supported by a large network of recruiters) that employed the nonstigmatizing slogan, “Whatever your weight, your opinion will count”. Participants were invited to complete a web-based questionnaire on their weight-related experiences. Self-reported measures were used to calculate each participant’s BMI, BID, SN, and QoL (a French obesity-specific QoL questionnaire was used to calculate the participants’ physical dimension of QoL scores [PHY-QoL], psychosocial dimension of QoL scores [PSY/SOC-QoL], and their total scores). The covariates included gender, age, subjective economic status, level of education, household size, and perceived health. The mediation/moderation tests were based on Hayes’ method. Results: Tests showed that the relationships between BMI and PHY-QoL, PSY/SOC-QoL, and TOT-QoL were partially mediated by BID in both males and females and by SN in females. Moreover, BID was a moderator of the relationship between BMI and PSY/SOC-QoL in males and females. SN was a moderator of the relationship between BMI and PSY/SOC-QoL in males and between BMI and total scores in males (when used without BID in the models). Conclusion: BID and SN should be considered as important factors in obesity management strategies. The study shows that targeting BMI only is not sufficient to improve the QoL of overweight and obese subjects, and that other variables, including perceptual factors, should be considered. Keywords: obesity, quality of life, mediators and moderators, body image
