Differences in Body Mass Index (BMI) Trends Across American Ethnicities

This study aims to determine if there are differences in body mass index (BMI) across ethnic groups in the United States. Modern medicine is increasingly going the way of personalized medicine, and existing literature has begun to suggest that cultural differences may have an effect on physical health. Initially, this study was to explore anorexia nervosa prevalence, but the data is simply not there; this led to a shift in focus to exploring health differences in terms of BMI. The data analyzed is from the National Health and Nutritional Examination Survey (NHANES) collected by the Centers of Disease Control and Prevention (CDC) from 1999-2013. The subjects used were aged 13-25, and the ethnicities compared were African American, Caucasian American, Mexican American, Other Hispanic American, Asian American, and Other (including multiracial). Statistical tests were run through the software program SAS and included ANOVA tests, t-tests, and z-tests. It was found that there are differences across ethnicities, and that there are far more differences among females than among males. Asian American males and Mexican American males appear to be the groups that caused males to have significant differences. Asian Americans were also found to have the lowest average BMI by far. On the other hand, African Americans and Mexican Americans appeared to have the highest average BMIs. Although these findings and others detailed in the paper are intriguing, the BMI data is not strictly normal, and is still not normalized even by transforming the variable into a log of BMI. The data is still right skewed, and must be attacked in the future with different transformations and non-parametric tests to increase the accuracy and strength of these findings.