Pathways linking BMI trajectories and mental health in an adult population-based cohort: role of emotional eating and body dissatisfaction.

backgroundOverweight and obesity are associated with poor mental health, and the association is bidirectional. Few studies have examined the association between weight change and mental health over time. We aimed to provide further insight into the association between weight gain and mental health, with a focus on emotional eating and body dissatisfaction as mediating factors.

methodsHeight and weight were self-reported upon registration, and in Spring 2022, 2023, and 2024 in the Specchio cohort (Geneva, Switzerland). BMI trajectories were estimated by (1) mixed-effects models to calculate participants' personal slopes (increase in BMI score per year), and (2) testing the odds of an upward BMI category transition from baseline to last follow-up. The associations of behavioural and psychosocial factors with BMI trajectories (slopes and transitions), and BMI trajectories with mental health outcomes were estimated using regressions adjusted for age, sex, education, and physical health condition. Structural equation modelling was used to test mediating pathways.

resultsAmong 7388 participants (59% women, mean age 51 years), factors associated with increasing BMI over 4 years included financial hardship, short sleep duration, less physical activity, more leisure screen time, depressive and anxiety symptoms, and emotional eating (β range [95% CI] = 0.03 [0, 0.05]-0.12 [0.09, 0.15]). Increasing BMI was associated with body dissatisfaction (β = 0.36 [0.33, 0.38]) and poorer quality of life (β = -0.06 [-0.09, -0.03]) at 4-year follow-up after adjustment for anxiety and depressive symptoms at baseline. Emotional eating partly mediated the association between anxiety and depressive symptoms at baseline and increasing BMI, and between financial hardship and increasing BMI. Body dissatisfaction and poorer self-rated health partly mediated the association between increasing BMI and quality of life at follow-up.

conclusionsEmotional eating and body dissatisfaction contribute to the association between BMI trajectories and mental health and should be considered in weight management and mental health promotion strategies.