Abstract

A study was conducted to investigate the validity of bioelectrical impedance measurement (BIM) for determining changes in body composition during treatment of obesity with an exercise and iet regimen. Eleven obese women, aged 38 = 57 yr (44 +/- 6.0 yr), participated in a weight reduction study. Before and after the weight reduction period, body composition was measured by the deuterium oxide (D2O) dilution and BIM methods. For both methods, the correlation coefficients were of the same order of magnitude under both pre- and postregimen conditions. Mean weight reduction was 3.59 +/- 1.518 kg and loss of total body fat was estimated to be 4.8 +/- 1.72 kg by the D2= method and 2.5 +/- 1.14 kg by the BIM method. Thus the BIM method underestimated the change in body fat compared with the D2O method. Changes in resistance (R) and height squared divided by R were not significant at the p>0.05 level. However, the mean change in fat-free mass (FFM) found by the D2O method was significantly greater than that found by the BIM method. Furthermore, there was no significant correlation between the changes in FFM estimated by the D2O and BIM methods. These results show that after weight reduction the BIM method overestimates body composition. It is concluded that the BIM method is not a valid approach for measuring the small changes in body composition that occur during treatment of obesity. Verf.-Referat