BMI may overestimate body fatness in youth with Down syndrome

By Linda Bandini, PhD
University of Massachusetts Medical School

Body mass index (BMI) is a way to screen for overweight and obesity. Little research has been done to determine whether the specific cut-offs (in the BMI scale) used to identify overweight and obesity in the general population are appropriate for identifying obesity in youth with Down syndrome (DS).

What did you do in your research?
The aim was to determine how valid the BMI is, to identify excess fat in youth with DS. We measured body composition in youth with DS, specifically how much of their body was fat and how much was lean body mass. We weighed and measured participants’ height, and used these to calculate their BMI. We compared the cut-off points for overweight and obesity based on their BMI to the amount of actual fat in their body.

What did you find out?
Youth with BMI in the range for obesity also had excessive body fat. However, many youth with BMI in the overweight range did not have high body fat.

What are the take-home messages?
For youth with DS, those with a BMI in the range for obesity will likely have excess body fat. However, for those youth with a BMI in the overweight range, many will not have excess body fat. Further research is needed on a larger population to confirm these findings and to determine if these cut-off points are associated with adverse health outcomes in youth with DS.

To learn more about these findings contact
Linda Bandini.

Full Journal Article
L. G. Bandini, L., Fleming, R., Scampini, R., Gleason, J., & Must, A. (2012). Is body mass index a useful measure of excess body fatness in adolescents and young adults with Down syndrome? Journal of Intellectual Disability Research, in press. Epub ahead of print.