How Accurate Is BMI as a Measure of Obesity?

Body-mass index (BMI) does not distinguish between fat mass and muscle or bone mass, leading some to question its use as a measure of obesity. Excess adiposity is considered a more accurate measure, but it is less convenient because it involves waist circumference measurements or dual-energy x-ray absorptiometry (DEXA) scans. Investigators used 2017–2018 health survey data to assess the concordance of BMI and excess adiposity in 2225 adults (mean age, 39) who had undergone anthropometric and DEXA measurements. Obesity as measured by BMI was defined as ≥30 kg/m² (or ≥27.5 kg/m² in non-Hispanic Asian participants). Standardized criteria were used for excess adiposity as determined by waist circumference (e.g., ≥102 cm for men other than non-H…