Work stress, weight gain and weight loss: evidence for bidirectional effects of job strain on body mass index in the Whitehall II study

Abstract

Objective: Previous research has focused on overall associations between work stress and body mass index (BMI) ignoring the possibility that stress may cause some people to eat less and lose weight and others to eat more. Using longitudinal data, we studied whether work stress induced weight loss in lean individuals and weight gain in overweight individuals. Design: Prospective cohort study. Subjects: A total of 7965 British civil servants (5547 men and 2418 women) aged 35–55 at study entry (The Whitehall II study). Measurements: Work stress, indicated by the job strain model and measured as job control, job demands and job strain, was assessed at baseline and BMI at baseline and at 5-year follow-up. Results: In men, the effect of job strain on weight gain and weight loss was dependent on baseline BMI (P⩽0.03). In the leanest quintile (BMI27 kg/m²), these stress indicators were associated with subsequent weight gain. No corresponding interaction was seen among women. Conclusion: Inconsistent findings reported by previous studies of stress and BMI have generally been interpreted to indicate the absence of an association. In light of our results, the possibility of differential effects of work stress should also be taken into account.