Increases in body mass index and waist circumference as outcomes of working overtime.

This epidemiologic study was undertaken to determine whether working overtime is associated with anthropometric indices and serum lipids, risk factors for obesity, in white-collar workers. Non-management white-collar male workers were eligible. Body weight and height, waist circumference, skinfold thickness, serum total cholesterol and triglycerides were measured. Weight, height and waist circumference data obtained 3 years previously were also used. Lifestyle information was obtained by means of a self-administered questionnaire. Overtime hours correlated significantly with the 3-year change in body mass index (r = 0.206, p < 0.0017) and waist circumference (r = 0.218, p = 0.0091), but not with either the most recent anthropometric indices or serum lipids. Overtime hours were also intercorrelated (r = 0.436, p < 0.0001) with dinner time. The present study suggested that working overtime is associated with the increases in BMI and waist circumference over a 3-year period although the associations were weak. Additionally, eating habits of those with working overtime might reflect an intervening effect on the anthropometric changes.