Disparate Body Composition Outcomes for Underwater Weighing, Dual-Energy X-Ray Absorptiometry, and Two Bioelectrical Impedance Devices in Overweight Young Adults

Introduction: As the prevalence of obesity rises, so does the need for reliable Body Composition (BC) methods.Many methods of BC analysis exist, however validity between methods has been questioned.Uncertainty exists within the scientific literature about which laboratory method and field measurement is applicable for the overweight population to estimate Percent Body Fat (% BF).There is scarce research comparing Hydrostatic Weighing (HW) and Dual Energy X-Ray Absorptiometry (DXA) with field methods in overweight individuals.The purpose of this study was to compare HW and DXA with Multi-Frequency (MF-BIA) and a Single-Frequency (SF-BIA) Bioelectrical Impedance (BIA) device.Methods: Twenty-five overweight and obese adults (BMI 30.1 ± 4.1 kg/ m 2 , 13 males, 12 females, ages 24.6 ± 4.7y) were randomly assessed by vertical SF-BIA, and supine MF-BIA against DXA and lastly HW.All participants followed standardized pre-testing guidelines for BC assessment.Agreement was assessed using a 2 (group) x 4 (method) RMANOVA and post-hoc t-tests were applied as appropriate.All methods of body composition were used and compared to DXA and HW.Results: Significant main effects between BC methods were observed F (1, 23) = 63.8, p < 0.001).Where % BF values were higher using the DXA (34.2 ± 10.6 %) vs. HW (28.2 ± 9.3 %) (p < 0.001).Additionally, % BF values were higher using the MF-BIA (30.9 ± 58.8 %) compared to the SF-BIA (26.2 ± 8.0%) (p < 0.001).%BF values were significantly correlated between SF-BIA and HW (p < 0.05, r = 0.902) as well as between MF-BIA and DXA (p < 0.05, r = 0.709).Conclusions: Differences in %BF were evident when comparing the vertical SF-BIA and supine MF-BIA with HW and DXA.The field method SF-BIA was found to correlate with the laboratory method HW.Whereas the field method MF-BIA was found to correlate with DXA.