An alternative to body mass index for standardizing body weight for stature

Although body mass index (BMI) has been adopted by WHO as an international measure of obesity, it lacks a theoretical basis, and empirical evidence suggests it is not valid for all populations. We determined standard weight-for-height using a model calibrated by multivariate analysis of observational data on body dimensions and health status in the USA (NHANES III). A multiple linear regression model based on a simple mathematical formulation accurately described the observed weight variations in this normal adult population. A standardized reference model using just two measurements (upper arm length and sitting height), readily applied in both clinical and research settings using lookup tables, improved explanatory power substantially compared to the best BMI formulation (r(2) increased 16.3% for males, 21.1% for females). Physical dysfunction and self-reported poor health showed strong trends with excess body weight. These findings need confirmation from larger population samples.