Work demands, family demands, and BMI in dual-earners families: A 16-year longitudinal study

Many scholars assert that work and family demands are negatively related to individuals' long-term physical health, but few studies have explicitly examined this relationship. Among these exceptions, most have employed a cross-sectional design that is limited in its ability to establish causality. We use body mass index (BMI) that generally increases during one's lifetime as an indicator of physical health, and seek to explore the amount of control individuals may have on this seemingly inevitable progression. Drawing on conservation of resources theory, we propose that an increase in demands-both in the work realm (e.g., the number of work hours) and in the family realm (e.g., the number of spouse work hours)-is likely to speed up the increase of BMI. Using a nationally representative sample of 4,264 individuals who were part of a dual-earner family between 1994 and 2010, we find that a within-person increase in weekly work hours, an increase in spouse weekly work hours, and an increase in the number of children are all related to a small within-person increase of the BMI growth trajectory. Within-person increase in work responsibility demands is related to a small within-person decrease in the BMI growth trajectory. We discuss implications of the relationships between work and family demands and long-term physical health.