News & Research

By: Felicia Breedy

31-July-2009 – Results of a new study indicate that the current methods used to estimate obesity, body mass index (BMI) and waistline circumference, may overestimate the incidence of obesity in African-Americans. Samuel Dagogo-Jack, MD, the recipient of a Mentor-Based Postdoctoral Fellowship Award from the American Diabetes Association, was highlighted in the June 22, 2009 issue of ScienceDaily. Dr. Dagogo-Jack and his postdoctoral fellow, Nicoleta Ionica, MD, compared the indirect measure of body fat, BMI, to body fat directly measured in the same patient using DEXA. They compared the correlation of these two measurements in both Caucasians and African-Americans. The correlation between DEXA-measured total fat and BMI was higher in whites than in blacks. 

BMI is an indirect method of estimating body fat, while waist circumference identifies abdominal obesity. BMI ranges identify a person who is underweight (less than 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9) or obese (more than 30). Waist measurements of greater than 40 inches in men and 35 inches in women are defined as obese. Increased waist circumference can indicate an increased risk for complications such as heart disease and diabetes. More time-consuming and expensive methods, such as the DEXA bone density scan or the computer tomography (CT), can directly measure the total body fat in a given region.

Non-diabetic research participants had a range of body weights and had one or both parents diagnosed with type 2 diabetes. The higher correlation of DEXA measured total body fat to BMI for Caucasians compared to African-Americans was also found for comparison of directly measured abdominal fat and waist circumference. This is a significant finding given that national data reports that African-Americans have higher rates of obesity and type 2 diabetes than Caucasians. Dr. Dagogo-Jack explains that African-Americans may have a higher muscle mass and this could explain the dissociation of BMI compared to body fat in the study data. Confirming research results in a larger study population is needed and could indicate the need to develop ethnic-specific values for obesity measures.

Results were presented June 16 at the Endocrine Society's 91st Annual Meeting in Washington, D.C. To read the news summary, select the following link: http://www.endo-society.org/media/press/upload/DAGOGO-JACK_FINAL.pdf