Full Papers

Behaviour, Appetite and Obesity

Body mass index bias in defining obesity of diverse young adults: the Training Intervention and Genetics of Exercise Response (TIGER) Study

Andrew S. Jackson^a1 c1, Kenneth J. Ellis^a2, Brian K. McFarlin^a1, Mary H. Sailors^a2 and Molly S. Bray^a2

^a1 Department of Health and Human Performance, The University of Houston, 3855 Holman Street, Houston, TX 77204-6015, USA

^a2 USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, USA

Abstract

The BMI cut-score used to define overweight and obesity was derived primarily using data from Caucasian men and women. The present study evaluated the racial/ethnic bias of BMI to estimate the adiposity of young men and women (aged 17–35 years) using dual-energy X-ray absorptiometry (DXA) determination of percentage body fat (DXA-BF%) as the referent standard. The samples were 806 women and 509 men who were tested from one to three times over 9 months providing 1300 observations for women and 820 observations for men. Linear mixed models (LMM) regression showed that with age and BMI controlled, DXA-BF% of African-American (AA) men and women, Asian-Indian men and women, Hispanic women and Asian women significantly differed from non-Hispanic white (NHW) men and women. For the same BMI of NHW women, the DXA-BF% of AA women was 1·76 % lower, but higher for Hispanic (1·65 %), Asian (2·65 %) and Asian-Indian (5·98 %) women. For the same BMI of NHW men, DXA-BF% of AA men was 4·59 % lower and 4·29 % higher for Asian-Indian men. Using the recommended BMI cut-scores to define overweight and obesity systematically overestimated overweight and obesity prevalence for AA men and women, and underestimated prevalence for Asian-Indian men and women, Asian women and Hispanic women. The present study extends the generalisability of research documenting the racial/ethnic bias of the universal overweight and obesity BMI cut-scores.

(Received October 20 2008)

(Revised January 29 2009)

(Accepted March 05 2009)

(Online publication April 06 2009)

Key Words:

• Percentage body fat;
• BMI;
• Overweight;
• Obesity;
• Diversity

Correspondence:

^c1 Corresponding author: Dr Andrew S. Jackson, fax +1713 743 9860, email udde@mac.com

Footnotes

Abbreviations: AA, African-American; BF%, percentage body fat; DXA, dual-energy X-ray absorptiometry; DXA-BF%, dual-energy X-ray absorptiometry determination of body fat percentage; LMM, linear mixed model; NHANES, National Health and Nutrition Examination Survey; NHW, non-Hispanic white; TIGER, Training Intervention and Genetics of Exercise Response