ÍNDICE DE MASSA GORDA RELATIVA (RFM) E BIOIMPEDÂNCIA ELÉTRICA NA ESTIMATIVA DA GORDURA CORPORAL EM ADULTOS: DIFERENÇAS ENTRE AS ESTIMATIVAS MÉDIAS DOS MÉTODOS AVALIADOS

Abstract

Assessment of body composition is essential for identifying alterations associated with cardiometabolic risk, since body mass index (BMI) does not adequately distinguish between fat mass and fat-free mass. In this context, relative fat mass (RFM) has been proposed as an anthropometric alternative for estimating body adiposity, standing out as an accessible and easy-to-apply indicator. The present study aimed to evaluate differences in mean body fat percentage estimates obtained by RFM and by tetrapolar and octapolar bioelectrical impedance analysis in adults. This descriptive, cross-sectional study with a quantitative approach was conducted with 67 adults (39 women and 28 men) recruited in Campo Grande, Mato Grosso do Sul, Brazil. Body composition was assessed using tetrapolar bioelectrical impedance analysis (Biodynamics 450) and octapolar bioelectrical impedance analysis (Tanita BC-418), while RFM was calculated from standardized anthropometric measurements. Differences in mean body fat percentage estimates were analyzed using repeated-measures ANOVA, stratified by sex (α = 0.05). Statistically significant differences were observed among the methods, with a greater magnitude in females (F = 14.5; p < 0.001; η²p = 0.277) than in males (F = 3.61; p = 0.050; η²p = 0.118). The findings indicate differences in mean estimates among the methods evaluated, with distinct patterns according to sex. It should be emphasized that the analyses performed allow the identification of differences between mean estimates but do not constitute a formal assessment of agreement between methods. Keywords.: body composition; bioelectrical impedance analysis; anthropometry.