Associations of job strain and working overtime with adverse health behaviors and obesity: Evidence from the Whitehall II Study, Helsinki Health Study, and the Japanese Civil Servants Study

Adverse health behaviors and obesity are key determinants of major chronic diseases. Evidence on work-related determinants of these behavioral risk factors is inconclusive, and comparative studies are especially lacking. We aimed to examine the associations between job strain, working overtime, adverse health behaviors, and obesity among 45-60-year-old white-collar employees of the Whitehall II Study from London (n = 3397), Helsinki Health Study (n = 6070), and the Japanese Civil Servants Study (n = 2213). Comparable data from all three cohorts were pooled, and logistic regression analysis was used, stratified by cohort and sex. Models were adjusted for age, occupational class, and marital status. Outcomes were unhealthy food habits, physical inactivity, heavy drinking, smoking, and obesity. In London, men reporting passive work were more likely to be physically inactive. A similar association was repeated among women in Helsinki. Additionally, high job strain was associated with physical inactivity among men in London and women in Helsinki. In London, women reporting passive work were less likely to be heavy drinkers and smokers. In Japan, men working overtime reported less smoking, whereas those with high job strain were more likely to smoke. Among men in Helsinki the association between working overtime and non-smoking was also suggested, but it reached statistical significance in the age-adjusted model only. Obesity was associated with working overtime among women in London. In conclusion, job strain and working overtime had some, albeit mostly weak and inconsistent, associations with adverse health behaviors and obesity in these middle-aged white-collar employee cohorts from Britain, Finland, and Japan.