Increases in weight during chronic stress are partially associated with a switch in food choice towards increased carbohydrate and saturated fat intake.

We examined if stress associated changes in weight and dietary restraint are associated with changes in the composition of foods consumed. Participants were 38 healthy women on a taught postgraduate university course. Data were obtained at the beginning of the semester and 15 weeks later just prior to a written course exam (the stressor). By using a within subject design, we measured the composition of food consumed, body mass index (BMI), levels of dietary restraint and salivary cortisol. In the larger study from which these data were obtained, it was shown that the effect of increased cortisol secretion on weight gain was mediated by a reduction in dietary restraint. The present data show that increased cortisol secretion, reduced dietary restraint and increased caloric intake, account for 73% of the variance in change in BMI. Further regression analysis indicated that the change in dietary restraint mediated the effect of change in cortisol on change in BMI. Final analysis revealed that the effect of these changes in dietary restraint on weight are partially mediated by increased caloric intake from carbohydrate and saturated fat, that is, a change in dietary composition partially accounts for the link between increased cortisol secretion through heightened hypothalamic-pituitary-adrenal activity resulting in weight gain. These data are consistent with a 'comfort food hypothesis', as they suggest that chronic stress can promote reward associated behaviour through reduced dietary restraint and consumption of food containing more carbohydrate and saturated fat.