Validity of the 4-compartment model using dual energy X-ray absorptiometry-derived body volume in overweight individuals.

The purpose of the present study was to assess the validity of dual-energy X-ray absorptiometry (DXA) to estimate body volume (BV) for use in a 4-compartment (4C) body composition model in an overweight/obese population. Body composition of 61 overweight/obese adults (age: 37.3 ± 10.0 years; height: 170.2 ± 9.5 cm; body mass: 97.1 ± 17.4 kg) was measured by 2 methods: a criterion 4C model and a DXA-derived BV 4C model. For both models, bioelectrical impedance spectroscopy was used to estimate total body water; total body bone mineral content was measured by a full-body DXA scan. For the criterion 4C model, BV was derived from air displacement plethysmography; for the DXA-4C model, BV was derived from previously published coefficients. Total error (TE) and standard error of the estimate (SEE) values for BV (TE = 1.11 L; SEE = 0.01 L) and body fat percentage (%fat) (TE = 2.92%; SEE = 0.32%) represented good to very good agreement between models. The DXA-derived measures of body composition (BV: 96.6 ± 18.1 L; %fat: 39.5% ± 8.1%; fat mass: 38.5 ± 11.9 kg), were significantly greater (p < 0.001) than 4C criterion measures (BV: 95.7 ± 17.6 L; %fat: 37.0% ± 7.6%; FM: 36.0 ± 10.8 kg) with the exception of lean mass, which was significantly lower (p < 0.001; DXA-4C: 58.2 ± 11.2 kg; criterion 4C: 60.7 ± 12.0 kg). Although small statistically significant mean differences were observed, TE and SEE results support the use of the DXA-4C method, which requires less time and equipment, for valid estimates of body composition in overweight/obese individuals.