Key result
Using BMI ≥30 kg/m2 to identify obesity in retired football players had poor specificity (0.36), misclassifying 87 of 129 subjects as obese when only 13 were truly obese based on percent body fat.
Why the study?
Does BMI accurately measure obesity compared to DEXA-measured percent body fat in retired football players?
Cross-Sectional (n=129)
Does BMI accurately measure obesity compared to DEXA-measured percent body fat in retired football players?
Effect estimate: Specificity 0.36
BMI is an inaccurate measure of true obesity (percent body fat) in retired professional football players, significantly overestimating obesity prevalence.
BMI misclassification warrants caution in retired football players; leaves open validation of DEXA-based metrics in athlete cohorts.
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/m 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.
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Hyman et al. (2012) conducted a cross-sectional in Obesity (n=129). Body mass index (BMI) vs. Percent body fat (%BF) by dual energy x-ray absorptiometry was evaluated on Specificity of BMI ≥ 30 kg/m2 to identify obesity compared to %BF (Specificity 0.36). Using BMI ≥30 kg/m2 to identify obesity in retired football players had poor specificity (0.36), misclassifying 87 of 129 subjects as obese when only 13 were truly obese based on percent body fat.
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