Comparison of near-infrared light spectroscopy, bioelectrical impedance and tritiated water techniques for the measurement of fat-free mass in humans.
Fat-free mass (FFM) was measured with three different methods: near-infrared spectroscopy, bioelectrical impedance and tritiated water technique, in 76 (39 females/37 males) subjects (age 47 +/- 2 [SEM] years, BMI 26.8 +/- 0.6 kg m-2). From bioelectrical impedance measurements FFM was calculated with manufacturers formula and a formula developed by Deurenberg et al [1]. FFM estimated from tritiated water technique (51.9 +/- 1.1 kg) was significantly lower than measured with near-infrared spectroscopy (57.4 +/- 1.4 kg; p < 0.001) and bioelectrical impedance calculated with manufacturers formula (59.6 +/- 1.5 kg; p < 0.001), but did not differ from the estimation made according to Deurenberg (52.1 +/- 1.2 kg). All the methods were highly intercorrelated, although the correlation coefficients were lower in the obese than lean subjects. Obesity seems to influence the bioimpedance method more than the near-infrared spectroscopy method. The results demonstrate that the near-infrared spectroscopy and the bioelectrical impedance method are simple and reproducible techniques to estimate fat-free mass in normal weight man. Both measurements are based partly on the anthropometric measurements. However, it is necessary to use an adjusted formula to obtain reliable measures of fat-free mass with the bioimpedance method in obese subjects.
Franssila-Kallunki
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Helsinki University Hospital, Fourth Department of Medicine, Finland.
D000273:Adipose Tissue; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D013055:Spectrophotometry, Infrared; D014316:Tritium; D014867:Water
D014867:Water; D014316:Tritium