Evaluation of modified multicompartment models to calculate body composition in healthy males.

Body volume was measured by underwater weighing (UWW) or with a skinfold caliper; bone mineral by dual energy X-ray absorptiometry (DXA); and body water by bioelectrical impedance analysis (BIA) in 22 healthy males. The percentage of water and bone mineral in fat-free mass had a significant effect on the calculated amount of fat using a two-compartment model. A three-compartment model based on field-adapted methods (skinfold thickness + BIA) to calculate body fat, correlated significantly with a more complex four-compartment model (UWW + BIA + DXA) (r = 0.95, p < 0.001). The advantages of three- and four-compartment equations are that they reduce the number of assumptions.