Additional work hours may lead to weight gain by decreasing exercise, causing substitution from meals prepared at home to fast food and pre-prepared processed food, or reducing sleep. Substitution toward unhealthy convenience foods could also influence the weight of one's spouse and children, while longer work hours for adults may further impact child weight by reducing parental supervision. I examine the effects of adult work hours on the body mass index (BMI) and obesity status of adults as well as the overweight status of children. Longer hours increase one's own BMI and probability of being obese, but have a smaller and statistically insignificant effect on these outcomes for one's spouse. Mothers', but not mother's spouse's, work hours affect children's probability of being overweight. My estimates imply that changes in labor force participation account for only 1.4% of the rise in adult obesity in recent decades, but a more substantial 10.4% of the growth in childhood overweight.