Validity Of Body Composition Measures By Inbody 770 Bioelectrical Impedance Analyzer

Abstract

PURPOSE: To test the validity of InBody 770 bioimpedance analyzer (IB770) against isotope dilution (D2O) for total body water (TBW) and against DXA for percent body fat (PBF). METHODS: Fifty-eight apparently healthy women (mean age 21.2 ±2.6 years, BMI 26.7 ±6.3) visited the Exercise Science Physiology Laboratory at KSU after an overnight fast. Subjects were given a 10g deuterium oxide solution (Cambridge Laboratories) to drink within 5 minutes and were asked to remain still in a reclining chair for 4 hours before providing a urine sample. Subjects were assessed via DXA for PBF and IB770 for both TBW and PBF. Frozen urine samples were shipped to an external laboratory for TBW assessment by mass spectroscopy. One extreme outlier was excluded from analysis due to probable D2O measurement error. Correlation analyses were used to assess the validity of TBW and PBF measures from IB770 compared to those from D20 and DXA. RESULTS: TBW estimates from IB770 were similar to those from D20 (32.6 ±5.9 vs. 32.3 ±6.0, respectively). PBF estimates from IB770 were also consistent with those from DXA (35.1 ±9.1 vs. 35.8 ±8.5, respectively). T-tests indicated that there were no significant differences among these measures (p>0.05 for both). IB770 measures for TBW and PBF were strongly correlated with D20 (r=.976, p<0.001) and DXA (r=.961, p<0.001), respectively. CONCLUSIONS: These data suggest that IB770 is a valid method for estimating TBW and PBF and may be appropriate for use as an alternative to D20 and DXA in a young female population.