Development and cross-validation of predictive equations for fat-free mass and lean soft tissue mass by bioelectrical impedance in Brazilian women

• Published in: European journal of clinical nutrition 2022-02, Vol.76 (2), p.288-296
• Main Authors: Costa, Roberto Fernandes da, Masset, Kalina Veruska da Silva Bezerra, Silva, Analiza M., Cabral, Breno Guilherme de Araújo Tinoco, Dantas, Paulo Moreira Silva
• Format: Article
• Language: English
• Subjects: 692/700/139/1735; 692/700/2814; 692/700/2817; Absorptiometry, Photon; Adult; Bioelectricity; Body Composition; Body fat; Body Mass Index; Brazil; Clinical Nutrition; Cross-Sectional Studies; Dual energy X-ray absorptiometry; Electric Impedance; Epidemiology; Exercise; Fat-free body mass; Female; Humans; Hydration; Impedance; Internal Medicine; Laboratories; Mathematical models; Medicine; Medicine & Public Health; Metabolic Diseases; Middle Aged; Physical education; Population; Public Health; Reproducibility of Results; Soft tissues; Validity; Weight; Womens health; Young Adult
• ISSN: 0954-3007; 1476-5640
• DOI: 10.1038/s41430-021-00946-x

Background/Objectives Bioelectrical impedance is one of the most used clinical techniques to assess body composition; however, it is necessary that the available predictive equations are valid for the evaluated subjects. This study aimed to develop and cross-validate equations for fat-free mass (FFM) and lean soft tissue mass (LSTM) by bioelectrical impedance for Brazilian women, in addition to test the validity of other available equations. Subjects/Methods Cross-sectional study with 222 women aged 20–59 years, randomly divided into two groups: development and cross-validation. The standard technique for assessing fat mass, FFM and LSTM was dual energy X-ray absorptiometry. Paired t test, multiple regression, and Bland–Altman plots were used to test the validity of the proposed models, as well as to perform cross-validation of the models. Results The equations derived in this study were: FFM = 16.284 + 0.442 × (Height 2 /Resistance) − 0.13 × age + 0.302 × Weight − 0.121 × Waist Circumference; r 2  = 0.86; SEE = 2.32 kg; and LSTM = 14.732 + 0.427 × (Height 2 /Resistance) − 0.125 × age + 0.291 × Weight − 0.115 × Waist Circumference; r 2  = 0.92; SEE = 2.29 kg. In addition, the new equation for FFM showed better agreement when compared to another equation developed for a Brazilian population. Conclusions The newly developed equations provide a valid FFM and LSTM estimation and are recommended for Brazilian women with similar characteristics.