Population density and obesity in rural China: Mediation effects of car ownership

Low-density built environments contribute to obesity by reducing physical activity. Nevertheless, few studies have explored the relationship between population density and obesity in rural areas and the mediation effect of car ownership. Using 2004–2015 data from the China Health and Nutrition Survey, we examine the association between population density and weight status in Chinese rural areas and identify whether car ownership mediates the association using fixed-effect models and a causal step approach. The results show that population density is positively associated with weight status in rural areas. A higher population density contributes to weight gain through increasing car ownership. However, the mediation effects of car ownership are statistically significant only for young adults. These findings highlight the rural–urban difference in the association between population density and weight status. Hence, policymakers should pay more attention to local contexts when they intervene in the built environment for obesity prevention.