Essays on health economics:trans fat policies, commuting, physical activity, and body mass index in the US

This thesis is made up of three empirical essays on obesity and chronic disease risk in the United States. Specifically, it examines health effects of trans fat reduction policies, the relationship between commuting and body mass index (BMI), and commuting and physical activity tradeoffs among individuals with differing levels of BMI. Chapter 2 examines the effects on individual-level measures of health from trans fat reduction policies in commercially prepared foods. Difference-in-difference estimation is used to identify changes in blood cholesterol levels prior to and after implementation of a series of related policies among restaurant meal consumers and non-consumers. Individuals with higher levels of consumption were found to have healthier cholesterol levels following implementation of the policies, while non-consumers saw less marked declines in cholesterol. Results remained robust to testing other obesity-related health measures less affected by trans fat consumption. Chapter 3 examines the relationship between active and sedentary commuting and BMI. Contrary to recent literature, this work finds little evidence of a relationship between increased sedentary commuting and higher BMI; instead this work suggests the link between commuting and poor health in the literature may be explained by a strong relationship between active commuting and lower BMI. These findings suggest further work is needed disentangle active and sedentary commuting choices. Chapter 4 revisits the relationship between sedentary commuting and physical activity to examine two issues. First, to find evidence of causality in this relationship and second, to examine whether this relationship varies by heterogeneity in health status. This work uses a two-part model of time use to examine both physical activity participation and duration decisions. Among healthy-weight and overweight individuals, commuting is associated with a decrease in participation, but not with duration of physical activities. However, among the obese, no significant relationship is observed. Results for nonobese males are robust to an instrumental variables approach (IV), however the instrument is not predictive of commuting behavior among obese males or among women, suggesting that determinants of commuting may be different for groups with differing health status