Heterogeneous Effects of Working Time Reduction on Overweight: Evidence from France

We examine the impact of a statutory reduction in working time (WTR) on overweight and obesity among white- and blue-collar workers in a large French firm. The firm implemented a 35-hour workweek one year prior to the national reform in all regions except Alsace–Moselle, where statutory WTR were smaller and working-time norms differ. We find that the WTR had heterogeneous effects across workers. Among blue-collar employees, the reform increased the likelihood of being overweight by 6.7 percentage points and reduced obesity by 2.6 percentage point. Heterogeneity by baseline BMI indicates that the increase in overweight among blue-collar workers is driven by individuals initially of normal weight. In contrast, among white-collar workers, individuals who were overweight or obese at baseline exhibit significant reductions in overweight. Overall, the results suggest that the effects of WTR vary systematically with the level of occupational sedentariness.