Health Effects of the American Diet: The Case of Immigrants

Michael Insler, United States Naval Academy
Sukanya Basu, Vassar College

We compare body mass index (BMI) of immigrants in the United States to that of natives. We observe that immigrants' BMI converges to natives' the longer they have lived in the U.S. We use data from the National Health and Nutritional Examination Survey, which contains extensive microdata on demographics, health, weight history, nutrition, physical activity, and more. We find that BMI-convergence persists across all age-ranges after controlling for a large set of observable demographic and physical characteristics. The phenomenon is also robust to compositional effects, and it occurs across all income levels. We explore the root causes of this “catch-up effect,” determining that it occurs primarily due to changes in immigrants' nutrition: The longer they live in the U.S., the more likely they are to adopt high fat, high sugar diets. Changes in their physical activity levels are small and thus have little impact on BMI.