Comparison of body composition methods in overweight and obese Brazilian women.

OBJECTIVE The purpose of this study was to compare skinfold thickness (SKF) and bioelectrical impedance analysis (BIA) of body composition using three different equations against dual-energy X-ray absorptiometry (DXA) in overweight and obese Brazilian women. SUBJECTS AND METHOD Thirty-four women (age 43.8 +/- 10.9 years; body mass index [BMI] 32.1 +/- 4.3 kg/m(2)) had percentage body fat (BF%), fat mass (FM) and fat-free mass (FFM) estimated by DXA, SKF and BIA (BIA-man: manufacturer's equation; and predictive obesity-specific equations of Segal and of Gray). Regression analysis, Bland-Altman plot analysis and intra-class correlation coefficient (ICC) were used to compare methods. RESULTS Absolute agreement between DXA and BIA-man was poor for all measures of body composition (BF% -6.8% +/- 3.7%, FM -3.1 +/- 3.6 kg, FFM 5.7 +/- 2.8 kg). BIA-Segal equation showed good absolute agreement with DXA for BF% (1.5% +/- 1.5%), FM (1.0 +/- 3.2 kg) and FFM (1.5 +/- 2.6 kg), albeit the limits of agreement were wide. BIA-Gray equation showed good absolute agreement with DXA for FM (2.3 +/- 4.1 kg), and smaller biases for BF% (0.05% +/- 4.4%) and FFM (0.2 +/- 2.9 kg), although wide limits of agreement. BIA-Gray and DXA showed the highest ICC among the pairs of methods. A good absolute agreement was observed between DXA and SKF for BF% (-2.3% +/- 5.8%), FM (0.09 +/- 4.7 kg), and FFM (2.4 +/- 4.4 kg), although limits of agreement were wider and ICC between DXA and SKF for BF% indicated poor degree of reproducibility. CONCLUSION These findings show that both BIA-Segal and BIA-Gray equations are suitable for BF%, FM and FFM estimations in overweight and obese women.