Objective: To compare bioelectrical impedance analysis (BIA) of body composition using three different methods against DXA in overweight and obese men.
Research Methods and Procedures: Forty-three healthy overweight or obese men (ages 25 to 60 years; BMI, 28 to 43 kg/m2) underwent BIA assessment of body composition using the ImpediMed SFB7 (version 6; ImpediMed, Ltd., Eight Mile Plains, Queensland, Australia) in multifrequency mode (Imp-MF) and DF50 single-frequency mode (Imp-SF) and the Tanita UltimateScale (Tanita Corp., Tokyo, Japan). Validity was assessed by comparison against DXA using linear regression and limits of agreement analysis.
Results: All three BIA methods showed good relative agreement with DXA [Imp-MF: fat mass (FM), r2 = 0.81; fat-free mass (FFM), r2 = 0.81; percentage body fat (BF%), r2 = 0.69; Imp-SF: FM, r2 = 0.65; FFM, r2 = 0.76; BF%, r2 = 0.40; Tanita: BF%, r2 = 0.44; all p < 0.001]. Absolute agreement between DXA and Imp-MF was poor, as indicated by a large bias and wide limits of agreement (bias, ±1.96 standard deviation; FM, −6.6 ± 7.7 kg; FFM, 8.0 ± 7.1 kg; BF%, −7.0 ± 6.6%). Imp-SF and Tanita exhibited a smaller bias but wide limits of agreement (Imp-SF: FM, −1.1 ± 8.5 kg; FFM, 2.5 ± 7.9 kg; BF%, −1.7 ± 7.3% Tanita: BF%, 1.2 ± 9.5%).
Discussion: Compared with DXA, Imp-MF produced large bias and wide limits of agreement, and its accuracy estimating body composition in overweight or obese men was poor. Imp-SF and Tanita demonstrated little bias and may be useful for group comparisons, but their utility for assessment of body composition in individuals is limited.