Work and non-work stressors, psychological distress and obesity: evidence from a 14-year study on Canadian workers

OBJECTIVE: This study aimed to evaluate the contribution of work, non-work and individual factors to obesity with regard to gender-related differences, and to clarify the mediating role that psychological distress plays in these dynamics in Canada from 1994 to 2008 using the Canadian National Population Health Survey (NPHS). DESIGN: Longitudinal. SETTINGS: The NPHS is a randomised longitudinal cohort study with biennial interviews of the Canadian adult population from 18 to 64. PARTICIPANTS: 5925 non-obese workers in cycle 1 (49% were women). MEASUREMENTS: Obesity was measured using the body mass index (BMI), with a threshold of BMI >30 kg/m(2). BMI was corrected in accordance with the recommendations of Connor Gorber et al to adjust for gender bias in responses. RESULTS: Of the work characteristics evaluated, only decision authority was associated with obesity for women but not for men. Living as a couple, child-related strains, psychotropic drug use, hypertension, being physically inactive and low psychological distress were obesity risk factors but were not moderated by gender. Overall, psychological distress did not mediate the associations that work factors have on obesity. CONCLUSIONS: Our study suggests that men and women differ little in the extent to which work, non-work and individual factors predict obesity. However, for women, the level of decision authority is associated with a lower obesity risk. In addition, psychological distress did not mediate the contribution of work factors and actually seems, contrary to expectations, to decrease the obesity risk when work, non-work and individual factors are taken into account.