Obesity among U.S. rural adults: Assessing selection and causation with prospective cohort data.

Rural adults in the U.S. have disproportionately high rates of obesity, but it is unclear whether this association exists because of selective migration or a contextual effect of the rural environment. Using nationally representative longitudinal data, this study investigates: (1) whether people with obesity select into rural counties, and (2) whether living in a rural area increases body weight after accounting for selection bias. Results indicate that people with obesity are less likely to move to a different county than people without obesity even after controlling for individual and household differences. Next, individual fixed effects regression models, which implicitly control for all time-constant variables, are used to produce a more robust estimate of the effect of rural residence on body weight. Rural residence predicts a significant increase in probability of obesity and body mass index. These results suggest that the association between rural residence and obesity in the United States is likely bidirectional.