Does body mass index adequately capture the relation of body composition and body size to health outcomes?

Body mass index (BMI) has become the most commonly used index of body composition in epidemiologic research. It has displaced weight, height, and other measures of body composition. In this paper, the authors show that use of BMI alone does not always capture adequately the joint relation of body composition and body size to health outcomes, and that such use often represents implausible restrictions on the relation. Use of body mass index and height or weight and height will often be needed to describe this relation and to control confounding by these variables.