Effects of Transportation Method Choice on Obesity

Studies suggest urban sprawl can be a contributing factor to obesity in the United States. A key channel in which urban sprawl affects obesity is hypothesized to be the changes in individuals' transportation methods. However, there is limited evidence that choosing physically active transportation methods for daily travels yields a significant weight loss. Simple correlations of transportation method choice and weight suffer from endogeneity problems since weight can be a determinant of the transportation method choice. In this paper, I explore the causal relationship between the choice of transportation method and obesity. Unlike previous studies, I address the endogeneity problem by using a two-step instrumental variables approach. I exploit the exogenous variation in transportation method choice caused by adverse weather conditions using the American Time Use Survey and the hourly observations from the National Oceanic and Atmospheric Administration. Corrected for endogeneity, I observe no evidence that choosing more physically active transportation methods results in lower future BMI. Taken as a whole, the calorie-loss benefits through encouraging more physical methods of transportation may not be strong enough in effectively fighting obesity.