Diagnostic Performance of BMI and Waist Circumference in Detecting Excess Adiposity

Objective This study compared the diagnostic performance of BMI, waist circumference (WC), and Lancet Commission (LC) criteria for assessing excess adiposity measured by dual‐energy X‐ray absorptiometry (DEXA) in US adults. Methods Using 2011–2018 NHANES data, we included 10,747 adults aged 20–59 years with relevant data. We evaluated the diagnostic performance (sensitivity, specificity, positive and negative predictive values [PPV, NPV], area under the curve [AUC]) of BMI thresholds, waist‐based measures, and LC criteria for excess adiposity, as defined by DEXA. Results The weighted prevalence of DEXA‐defined excess adiposity was 36.4%. CDC BMI thresholds demonstrated 74.6% sensitivity and 82.2% specificity (PPV, 67.0%; NPV, 87.0%). Waist‐based measures showed higher sensitivity and lower specificity than BMI; NHLBI WC thresholds produced 88.5% sensitivity and 66.7% specificity. LC criteria performed variably: BMI plus ≥ 1 waist measure had 74.6% sensitivity and 82.2% specificity, whereas ≥ 2 waist measures had 88.5% sensitivity and 66.8% specificity. The AUC values were 0.876 for BMI, 0.882 for WC, 0.887 for waist to height ratio, and 0.715 for waist to hip ratio. Conclusions Waist‐based definitions were more sensitive than BMI, whereas BMI provided greater specificity. LC criteria performed comparably to existing definitions. Incorporating WC into screening may improve the detection of excess adiposity.