Assessment of fat-free mass using bioelectrical impedance measurements of the human body

• Published in: The American journal of clinical nutrition Vol. 41; no. 4; pp. 810 - 817
• Main Authors: Lukaski, HC, Johnson, PE, Bolonchuk, WW, Lykken, GI
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.04.1985; American Society for Clinical Nutrition
• Subjects: Adipose Tissue - anatomy & histology; Adult; AGUA; ANALYTICAL METHODS; Applied sciences; Biological and medical sciences; BODY COMPOSITION; Body Water - analysis; EAU; Electric Conductivity; Electrochemistry; Electrodes; Electrodiagnosis. Electric activity recording; Exact sciences and technology; fat-free mass; Human body composition; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Mathematics; Medical sciences; nutritional assessment; Nutritional Physiological Phenomena; Other techniques and industries; POTASIO; POTASSIUM; Potassium - analysis; total body potassium; total body water; WATER; whole body impedance; whole body impedance; fat-free mass; Human body composition; nutritional assessment; total body water; total body potassium; Correlation coefficient; Measurement; Electrical conductivity; Whole body; Densitometry; Body composition; Plethysmography; Electrical impedance
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/41.4.810

A method which involves the measurement of bioelectrical resistive impedance (R) for the estimation of human body composition is described. This method is based upon the principle that the electrical conductivity of the fat-free tissue mass (FFM) is far greater than that of fat. Determinations of R were made in 37 healthy men aged 28.8 ± 7.1 yr (mean ± SD) using an electrical impedance Plethysmograph with a four electrode arrangement that introduces a painless signal (800 µA at 50 kHz) into the body. FFM was assessed by hydrodensitometry and ranged from 44.6–98.1 kg. Total body water (TBW) determined by D2O dilution and total body potassium (TBK) from whole body counting were 50.6 ± 10.3 L and 167.5 ± 38.1 g, respectively. Test-retest correlation coefficient was 0.99 for a single R measurement and the reliability coefficient for a single R measurement over 5 days was 0.99. Linear relationships were found between R values and FFM (r = −0.86), TBW (r = −0.86), and TBK (r = −0.79). Significant (p < 0.01) increases in the correlation coefficients were observed when the predictor Ht2/R was regressed against FFM (r = 0.98), TBW (r = 0.95), and TBK (r = 0.96). These data indicate that the bioelectrical impedance technique is a reliable and valid approach for the estimation of human body composition. This method is safe, noninvasive, provides rapid measurements, requires little operator skill and subject cooperation, and is portable. Further validation of this method is recommended in subjects with abnormal body composition.