Comparison of three equations for predicting the body fat by bioimpedance in young obese females

Abstract

Introduction: The bioelectrical impedance (BIA) has been widely used for monitoring body composition of individuals of different ages and nutritional statuses. However, it is unknown which of the equations for children and adolescents is the most recommended to be used for adolescents who are overweight. Objective: To assess the agreement of the BIA method using three different equations with dual energy X-ray absorptiometry (DXA) for analysis of body composition in overweight and obesity. Methods: Twenty-seven female adolescents with overweight or obesity were included in this study. The percentage of body fat (%BF), fat mass (FM) and fat-free mass (FFM) were evaluated by DXA and BIA using the equations proposed by Houtkooper, Schaefer and Deurenberg. Oneway ANOVA, Bland-Altman plots and the intraclass correlation coefficient were used for comparison and verification of the agreement among the methods. Results: BIA using the equation proposed by Houtkooper was the only one that showed no statistically significant difference in the estimating %BF, FM and FFM compared to DXA and showed good agreement with DXA in estimating %BF (-1.9±3.29), FM (1.5±2.59) and FFM (1.4±2.60) and good reproducibility for %BF (0.81), FM (0.96) and FFM (0.89). The Schaefer and Deurenberg equations showed less agreement with DXA, overestimating the MG and underestimating the FFM, and presented moderate to low reproducibility in most measures of body composition. Conclusion: When we compared the three equations proposed to BIA with DXA, we find that the Houtkooper equation was the best agreed with DXA and showed good reproducibility for estimate %BF, FM and FFM in female adolescents with overweight and obesity.