THE RELATION OF FAT-FREE BODY TO HEIGHT IN OBESE WOMEN DURING WEIGHT LOSS665

Obese individuals have an expanded fat mass. In addition, they may also have a greater fat-free mass (FFM) than their non-obese counterparts. The purpose of this investigation was to examine the relation of FFM to height in the obese before and after significant weight loss. Seventeen obese women participated in a very low calorie diet program (420-800 kcal/day) for 12 weeks. Measures of body weight (BW), body density (BD) (hydrostatic weighing), total body bone mineral content (BMC) (dual-energy radiography, QDR-Hololgic), and total body water (TBW) (deuterium dilution) were obtained. Percent fat was calculated from BD using a multi-component model. Estimates of FFM were calculated as BW - fat weight. Data for height and FFM at baseline and after weight loss were plotted in comparison to the regression line and standard deviations from equations developed by Lohman & Slaughter (1980) predicting the relation of FFM to height using data for non-athletic women. There was a significant decrease in BW (16.62 kg), fat mass (12.05 kg), and FFM (4.58 kg) over the 12 week diet period. At baseline, 14 of the 17 women had a FFM to height relationship of greater than 2 SD's above the mean predicted value, suggesting that the subjects had a greater FFM than would be expected based on height. After weight loss, only 4 of the 17 women had a FFM to height relationship greater than 2 SD's above the mean predicted value. No values fell below the mean predicted FFM for height. These results suggest that some portion of the larger FFM may have been the result of being obese and that the relation of FFM to height tends to normalize with weight loss.