Development and cross-validation of predictive equations of fat-free mass by bioelectrical impedance for Brazilian men aged 20 to 59 years old


  • Roberto Fernandes Costa
  • Kalina Bezerra Masset
  • Elys Costa Sousa
  • Breno Tinoco Cabral
  • Paulo Silva Dantas



The aim of this study was to develop and validate a fat free mass predictive equation by bioelectrical impedance for men of the Brazilian population. A total of 203 males aged 20 to 59 years were randomly divided into two groups: development (102) and cross-validation (101). The standard technique was dual energy radiological Abortometry (DXA). Paired t-test, multiple regression and plot of Bland-Altman were used to test the validity of the proposed model. The equation derived from the study was: FFM = 17.57 + 0.348 (Stature2/ Resistance) + 0.513 Body Mass - 0.283 Abdominal Perimeter + 0.079 Reactance - 0.038 age; concordance correlation coefficient - CCC = 0.937; r2= 0.89; standard error of estimate - SEE = 2.55 kg; pure error - PE = 2.51 kg. Thus, the new equation proposed provides a valid estimate of fat-free mass and is recommended for men with similar characteristics.



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