[The use of the impedance measurement technic for calculating body fat mass. A validity study]

The body composition of water and fat may be calculated on the basis of measurements of its impedance. Calculations are based on algorithms developed by all measurements of the body compositions of a reference material, by means of standard methods (eg hydrodensiometry, total body water by isotope dilutimetry). A commencial impedance analyser with built-in algorithm for calculation of total body water and body fat mass was evaluated and compared with measurements of the total body water in 42 young men and women. Very good agreement was found (mean values for total water were 34.2 and 33.5, respectively, for women and 46.8 and 47.0, respectively, for men). These calculations of total body water correlated better with the reference values than calculations from four other algorithms published in the literature. Simple anthropometric measurements (skin-fold thickness, BMI) resulted in significantly higher calculations of body fat mass than calculations based on impedance measurement. This study has shown that the technique of impedance measurement has good reliable validity for calculation of the body fat mass and that, on account of its simplicity, the method is suitable for field studies and also individual measurements.