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

Abstract

Background:

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 (FFM_BIA/HF) and FF-BIA (FFM_BIA/FF) were 61.3 ± 1.3 kg and 58.1 ± 0.9 kg, respectively (P < 0.001). In subjects with BMI <25 kg/m², FFM_BIA/FF was not significantly different compared to FFM_BIA/HF (+0.2 kg; P = 0.8). However, FFM_BIA/FF was 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. FFM_BIA/FF was the only significant independent predictor of FFM_BIA/HF (P < 0.001) in linear regression analyses using clinical and FF-BIA variables, but introducing BMI in the model added precision.

Conclusion:

FFM_BIA/FF correlates closely with FFM_BIA/HF across all quintiles of BMI, but FF-BIA gives lower FFM in overweight and obese subjects.