Sex-specific Variability In Body Composition Estimations By Bioelectrical Impedance Analysis As Compared To Dual Energy X-ray Absorptiometry And Hydrostatic Weighing.

Abstract

Estimations of body composition in overweight and obese adults can be made using techniques such as hydrostatic weighing (HW), dual energy X-ray absorptiometry (DXA), single frequency vertical (SF-BIA) and multi-frequency supine (MF-BIA) bioelectrical impedance analyses. PURPOSE: The purpose of this study was to determine if sex-specific differences would be apparent in BIA estimations of body fat (%BF) when compared to DXA and HW for overweight and obese adults. METHODS: In a single session, 13 men (29.4±3.6 kg/m2) and 12 women (30.8±4.6 kg/m2) consented and were randomly assessed by DXA, vertical SF-BIA, and supine MF-BIA; HW was performed last. A 2 (sex) x 4 (method) RMANOVA was used. Post-hoc t-tests were applied as appropriate. Analyses were performed via SPSS v23 with significance at the .05 level. RESULTS: There were significant main effects for method (F(1,23) =52.244, p< .001) and sex (F(1,23)=42.39, p< .001); men were consistently leaner than women. For the men (26.23±6.0 yr), MF-BIA (25.1±7.1%BF) and SF-BIA (20.1±5.7%BF) were similar to HW (20.8±6.1%BF; p=.123 and .368, respectively). Compared to DXA (25.5±6.6%BF), MF-BIA was similar (p=0.863, but SF-BIA underestimated DXA %BF (p<.001). CONCLUSIONS: Sex-specific similarities and differences in %BF are evident when comparing vertical SF-BIA and supine MF-BIA to HW and DXA. For the men, MF-BIA, but not SF-BIA, yielded similar results to HW and DXA. For the women, MF-BIA was similar to HW, but, like SF-BIA, was significantly lower than DXA. For this sample, MF-BIA appears interchangeable with DXA (men) and HW (both sexes).