Objective: To assess the accuracy of body mass index (BMI) as a measure of obesity compared with percent body fat (%BF) directly measured by dual energy x-ray absorptiometry among retired football players.
Methods: The level of agreement between BMI and %BF as measures of obesity was assessed by sensitivity, specificity, and the kappa statistic among 129 retired football players. Logistic regression was used to investigate the association between obesity and selected comorbidities.
Results: Using BMI 30 kg/m2 or higher to identify obesity had poor specificity (0.36): 87 of 129 subjects were classified as obese, yet only 13 were truly obese based on %BF. Although BMI did not reliably indicate true %BF-obesity, BMI-obesity was significantly correlated with lineman position (P < 0.0001), years played (P = 0.03), and obstructive sleep apnea (P = 0.0005).
Conclusions: Percent body fat measured by dual energy x-ray absorptiometry provides a more accurate measure of obesity than does BMI among retired football players.
From the Division of General Internal Medicine (Dr Hyman), Department of Medicine; Department of Environmental Health Science (Ms Dang), School of Public Health; and Department of Family Medicine (Dr Liu), David Geffen School of Medicine, University of California, Los Angeles.
Address correspondence to: Yihang Liu, MD, MA, MS, UCLA Family Medicine, 10880 Wilshire, Suite 1800, Los Angeles, CA 90024 (email@example.com).
This project was supported in part by the nonprofit Veritas Medicus Fund of the American Academy of Disability Evaluating Physicians.
The authors declare there is no conflict of interest.