Do environmental factors drive obesity? Evidence from international graduate students
利用美国40所公立大学的国际研究生数据，研究发现居住地肥胖率越高，学生体重增加越多，为环境因素影响肥胖提供了因果证据。
International students offer a unique window into the role environmental factors play in driving obesity. Naïve estimates of the relationship between environmental factors and obesity are often plagued by reverse causation, sample selection, and omitted variable bias. In this study, we survey international students at 40 public universities across the United States. We use this unique data to link the weight gain of international students to the prevalence of obesity where they live. We argue that our estimates are less likely to be biased as international students have limited control over the environment to which they are exposed upon arrival in the United States. We find that students living in areas with a higher prevalence of obesity show a biologically important and statistically significantly greater increase in weight as compared to those living in areas with a lower prevalence of obesity. Results provide cautious evidence that environmental characteristics of a region can affect the weight gain of individuals.