The Fenland Study is supported by Medical Research Council (MRC) grant MC_U106179471 (to NJW). This work was supported by MRC grants MC_UU_12015/2 (to NJW), MC_UU_12015/1 (to KKO). Genotyping was supported by MRC grant MC_PC_13046. The EDEN study is supported by the Foundation for Medical Research (FRM); French Ministry of Research: Federative Research Institutes and Cohort Program; Human Nutrition National Research Program, French National Institute of Health and Medical Research; Diabetes National Research Program [through a collaboration with the French Association of Diabetic Patients (AFD)]; French Ministry of Health; French Agency for Environment Security (AFSSET); French National Institute for Population Health Surveillance (InVS); Paris-Sud University; French National Institute for Health Education (INPES); Nestlé Mutuelle Générale de l’Education Nationale (MGEN); Francophone Association for the Study of Diabetes and Metabolism (ALFEDIAM); National Agency for Research (ANR nonthematic program); and National Institute for Research in Public Health (IRESP: TGIR health cohorts 2008 program). The EDEN study authors received no specific funding for this work.

Abstract

Background: Many genetic variants show highly robust associations with body mass index (BMI). However, the mechanisms through which genetic susceptibility to obesity operates are not well understood. Potentially modifiable mechanisms, including eating behaviors, are of particular interest to public health.

Objective: Here we explore whether eating behaviors mediate or modify genetic susceptibility to obesity.

Design: Genetic risk scores for BMI (BMI-GRSs) were calculated for 3515 and 2154 adults in the Fenland and EDEN (Etude des déterminants pré et postnatals de la santé et du développement de l'enfant) population-based cohort studies, respectively. The eating behaviors—emotional eating, uncontrolled eating, and cognitive restraint—were measured through the use of a validated questionnaire. The mediating effect of each eating behavior on the association between the BMI-GRS and measured BMI was assessed by using the Sobel test. In addition, we tested for interactions between each eating behavior and the BMI-GRS on BMI.

Results: The association between the BMI-GRS and BMI was mediated by both emotional eating (EDEN: P-Sobel = 0.01; Fenland: P-Sobel = 0.02) and uncontrolled eating (EDEN: P-Sobel = 0.04; Fenland: P-Sobel = 0.0006) in both sexes combined. Cognitive restraint did not mediate this association (P-Sobel > 0.10), except among EDEN women (P-Sobel = 0.0009). Cognitive restraint modified the relation between the BMI-GRS and BMI among men (EDEN: P-interaction = 0.0001; Fenland: P-interaction = 0.04) and Fenland women (P-interaction = 0.0004). By tertiles of cognitive restraint, the association between the BMI-GRS and BMI was strongest in the lowest tertile of cognitive restraint, and weakest in the highest tertile.

Conclusions: Genetic susceptibility to obesity was partially mediated by the “appetitive” eating behavior traits (uncontrolled and emotional eating) and, in 3 of the 4 population groups studied, was modified by cognitive restraint. High levels of cognitive control over eating appear to attenuate the genetic susceptibility to obesity. Future research into interventions designed to support restraint may help to protect genetically susceptible individuals from weight gain.