Effect of the Interaction between Mental Stress and Eating Pattern on Body Mass Index Gain in Healthy Japanese Male Workers

BACKGROUND The effect of the interaction between long-term mental stress and eating habits on weight gain has not been confirmed in humans. METHODS A population of 1080 healthy Japanese male local government employees without lifestyle-related diseases at baseline were studied [corrected]. Height and weight were measured and perception of mental stress and the frequency of eating to satiety, drinking, smoking, and exercise were surveyed by means of a questionnaire in both 1997 and 2002. Exposure patterns during this 5-year period were classified as low or high. Information on daily food and energy intake was collected in 2002. The effect of the interaction between stress and the frequency of eating to satiety on change in BMI (DeltaBMI) during this 5-year period was examined by 2-way analysis of variance (ANOVA) and covariance (ANCOVA) adjusted for age, BMI at baseline, and other lifestyle habits. The association between satiation eating and DeltaBMI was compared between participants with high and low levels of stress. RESULTS Stress and satiation eating were not significantly mutually correlated. Two-way ANCOVA showed a significant interaction (F = 4.90, P = 0.03) between mental stress and satiation eating. Among participants with a high level of stress, BMI gain was significantly larger in those who ate to satiety than in those who ate moderately, when DeltaBMI was unadjusted or adjusted for covariates (adjusted mean [SE]: 0.34 +/- 0.06 kg/m(2) vs. 0.12 +/- 0.07 kg/m(2), P = 0.002). Among participants with a low level of stress no such difference was observed. These results were unchanged after further adjustment for energy intake in 2002. CONCLUSION In this population, eating pattern interacted with long-term mental stress to produce a larger body mass gain in satiation eaters than in moderate eaters among participants with a high level of stress, independent of energy intake or other lifestyle habits.