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

Abstract

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 microA 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 less than 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.

Short‐term resource allocation during extensive athletic competition

“…It is appreciated that in vivo measurements cannot measure body composition directly, but rather make predictions from other physiological metrics. BIA was chosen because of its speed, simplicity, high precision and suitability for assessing short‐term changes in individuals (Johnson, Bolonchuk, & Lykken, 1985; Roubenoff, 1996; Wells & Fewtrell, 2006). In order to avoid the inherent problems of predicting total body water (TBW), regression equations for converting between impedance and TBW were avoided.…”

Changes in fat-free mass during significant weight loss: a systematic review

“…However, BIA has not been validated in obese subjects or with weight loss and studies using it were excluded from the analysis. 17,18 Estimates of total body potassium (TBK), although indicative of the aqueous volume of lean tissue, were also excluded owing to concern about assumptions of constant TBK/FFM ratio. 19 Finally, although multislice magnetic resonance imaging (MRI) is sensitive to changes in tissue volumes 20 and FFM, 21 it is incompatible with techniques that measure whole body fat and fat free as two compartments.…”

Among inflammation and coagulation markers, PAI-1 is a true component of the metabolic syndrome

“…Hip circumference was measured at the level of the trochanter major and the waist-to-hip ratio (WHR) was calculated. Body composition was determined by bio-impedance analysis as described by Lukaski et al 11 and fat mass percentage was calculated, using the formula of Deurenberg et al 12 Systolic and diastolic blood pressures were determined on the right arm of the patient, after at least 5 min resting, using a mercury sphygmomanometer.…”