Techniques used in the measurement of body composition: an overview with emphasis on bioelectrical impedance analysis.

The study of human body composition is now a distinct research area consisting of three interconnected parts: the five-level model and associated rules that govern the relations between components, body-composition methodology, and biological factors that influence body composition. In this overview we summarize fundamental concepts that relate to the five-level model and body-composition methods. We show how these concepts can be used to outline the essential features needed to critically evaluate the bioelectrical impedance analysis method. Body-composition research is a rapidly expanding area and in-depth systematic evaluation of new methods is a vital aspect of the field's growth.