Techniques for the measurement of body composition: a practical guide.

This paper discusses some of the practical aspects of both reference body composition methods (densitometry, isotope dilution methods, in vivo neutron activation analysis, dual energy X-ray absorptiometry, computerized tomographic scanning and magnetic resonance imaging) and bedsides or field techniques (weight and height indices, skinfold thicknesses impedance/resistance, near infra-red interactance and 24 hour creatinine excretion). Some techniques measure gross composition, in terms of fat and fat-free mass, or the components of fat-free tissue, such as water, mineral and protein, while other methods measure the mass of individual tissues, organs or body segments. The choice of a specific method for a particular study depends on various considerations including accuracy, precision, subject acceptability, convenience, cost, radiation exposure, and the need for observer training. The relative advantages and disadvantages of each method are discussed with these considerations in mind.