Rapid weight loss and lean tissue: evidence for comparable body composition and metabolic rate in differing rates of weight loss.

In assessing the desirability of very low calorie diets (VLCD) it is important to assess whether the additional calorie deprivation associated with a VLCD is within the range of physiological adaptation of normal people: specifically that the overweight person will return to normality in terms of body composition and metabolic rate. Comparison of fat free mass (FFM) and resting metabolic rate (RMR) change was made between two groups of dieting female subjects, whose weight loss was 1.9 kg/week (group A) and 1.1 kg/week (group B) over 8 weeks of diet. Body composition studies showed an equivalent FFM/Wt loss of 0.42 and 0.44 in the high and low weight loss groups respectively. As expected from the greater loss of weight, resting metabolic rate fell further in group A, but the RMR/FFM ratio remained the same (group A 21.3; group B 22.1). There is no evidence to suggest that the rate of weight loss achieved by VLCD is associated with any detriment to body composition or metabolic rate.