Body composition in urban South Asian women; development of a bioelectrical impedance analysis prediction equation

Background: Assessment of body composition plays a significant role in combating chronic disease among South Asians. Accurate assessment of body composition by bioelectrical impedance analysis (BIA) requires population-specific equations which are currently unavailable for urban South Asian women. Aim: To assess validity of direct BIA assessment and selected equations for prediction of total body water (TBW), against Deuterium ((H2O)-H-2) dilution and develop and validate a population-specific TBW equation for urban South Asian women. Subjects and method: Data of 80 urban Sri Lankan women (30-45 years) were used for this analysis. Body composition was assessed by (H2O)-H-2 dilution (reference) and BIA. Available BIA equations were assessed for validity. A new TBW equation was generated and validated. Results: Direct BIA measurements and other equations did not meet validation criteria in predicting TBW. TBW by the new equation (TBW = 3.443 + 0.342 x (height(2)/impedance) + 0.176 x weight) correlated (p<0.001) with TBW by reference method. TBW using the new equation was not significantly different (25.30 +/- 2.4 kg) from the reference (25.32 +/- 2.7 kg). Conclusion: Direct use of TBW by instrument and existing equations are less suitable for this population. The new TBW equation is suitable for body composition assessment in urban South Asian women.