Comparison of Foot-to-Foot and Hand-to-Foot Bioelectrical Impedance Methods in a Population with a Wide Range of Body Mass Indices.

AbstractBackground:Several techniques are currently used for measurement of body composition. Bioelectrical impedance assessment (BIA) is a simple, noninvasive method of assessing body composition. We aimed to compare multifrequency hand-to-foot (HF-BIA) and foot-to-foot (FF-BIA) bioelectrical impedance analysis techniques to assess fat-free mass (FFM) in a population with a wide range of body mass indices (BMI).Methods:This was a cross-sectional study of 198 adult subjects. Anthropometric and BIA measures (HF-BIA with Hydra ICF/ECF, Xitron Technologies and FF-BIA with Tanita, model TBF-300A) were recorded after a 12-h fast.Results:Participants had a mean age of 42 years and BMI of 33.5 ± 0.7 (range, 17.7–65.6) kg/m2. Mean FFM with HF-BIA (FFMBIA/HF) and FF-BIA (FFMBIA/FF) were 61.3 ± 1.3 kg and 58.1 ± 0.9 kg, respectively (P< 0.001). In subjects with BMI <25 kg/m2, FFMBIA/FFwas not significantly different compared to FFMBIA/HF(+0.2 kg; P= 0.8). However, FFMBIA/FFwas significantly lower in subjects with BMI 25–30 kg/m2(−2.0 kg; P= 0.009), 30–34 kg/m2(−1.8 kg; P= 0.04), 34–42 kg/m2(−4.7 kg; P< 0.001) and >42 kg/m2(−8.0 kg; P= 0.001). Pearson correlations between both methods were very high for FFM (r= 0.92), fat mass (r= 0.91), and % fat mass (r= 0.85), all P< 0.001. Correlation coefficients for FFM were high in each quintile of BMI. FFMBIA/FFwas the only significant independent predictor of FFMBIA/HF(P< 0.001) in linear regression analyses using clinical and FF-BIA variables, but introducing BMI in the model added precision.Conclusion:FFMBIA/FFcorrelates closely with FFMBIA/HFacross all quintiles of BMI, but FF-BIA gives lower FFM in overweight and obese subjects. [ABSTRACT FROM AUTHOR]