Validity of a Multi-compartment Body Composition Model Using Body Volume Derived from Dual-Energy X-ray Absorptiometry

Abstract

Measuring body composition may serve as an important clinical tool in assessing health risks. A four-compartment (4C) model utilizing body mass, body volume (BV), total body water (TBW), and bone mineral content (BMC) is a widely accepted criterion method for predicting body composition. BV is commonly assessed using air displacement plethysmography (BodPod). However, dual-energy x-ray absorptiometry (DXA) has been proposed as an alternative method for BV, reducing time and equipment required for a multi-compartment model. PURPOSE: To assess the validity of a DXA-derived body volume 4C model for calculation of percent body fat (%BF), fat mass (FM), and lean mass (LM). METHODS: A total sample of 126 men and women (Mean ± SD; Age: 35.8 ± 9.4 years; Body Mass: 97.31 ± 20.4 kg; Height: 176.04 ± 9.2 cm) completed a 4C body composition reference assessment, including BV from Bodpod, TBW from bioelectrical impedance spectroscopy, and BMC from DXA. Using a sample of 99 subjects, a DXA-derived body volume 4C model (4C DXA) was created by linearly regressing BodPod BV with DXA FM, LM, and BMC as independent factors. The 4C DXA model was validated in a sub-sample of 27 subjects. RESULTS: The density coefficients of FM, LM, and BMC determined to predict BV were 0.84 (p CONCLUSIONS: The 4C DXA model using the determined coefficients was demonstrated to be a valid method of estimating FM, LM, and %BF when compared to a traditional 4C model. The alternative method of predicting BV using DXA may eliminate the need for a BodPod when using a 4C model to assess body composition.