The theory that adaptive changes in the resting metabolic rate (RMR) of weight-reduced persons predispose them to regain weight is challenged by new evidence published in The American Journal of Clinical Nutrition. The set point theory holds that the body has a homeostatic feedback system which causes an adaptation in the energy efficiency of metabolic processes during calorie restriction, with the aim of maintaining fixed fat stores and body weight. In a study of 24 overweight postmenopausal women, Weinsier et al. found no significant differences in RMR between the subjects once they had stabilized after weight loss and a control group of never-overweight women. Four years after their weight loss, the overweight subjects had regained an average of 10.9 kg, and their RMR's were not significantly different than they had been previously. The authors conclude that a factor other than changes in metabolic rate must be responsible for weight regain in dieters.
The study involved a group of 24 postmenopausal women who were all overweight and were matched with a control group of 24 never-overweight subjects. The overweight women participated in a series of 10 day study phases, each involving admission to a clinical research center. In stage 1 the overweight subjects consumed an amount of calories suitable to maintain their current weight and match their energy output with their energy intake. In stage 2, they consumed a calorie-restricted diet until they were reduced to normal body weight, with an average weight loss of 13 kg. In stage 3 energy balance was stabilized for the subjects at their new, weight-reduced state. As predicted, the overweight women's RMR decreased significantly in response to dieting, falling 6% within 10 days of calorie restriction and remaining 6% below baseline despite 3-5 months of continued calorie restriction. However, within 10 days of restoring energy balance while remaining in the weight-reduced state, the formerly-overweight subjects' RMR's, after adjustment for body composition, were similar to the RMRs of the never-overweight control group. These findings suggest that the set point theory might have come about through measurements of RMR taken immediately following calorie restriction, but before energy balance had been restored, thus giving the misleading impression that weight-reduced persons were hypometabolic and hence more prone to weight regain.
Weinsier, Roland L et al. Do adaptive changes in metabolic rate favor weight regain in weight-reduced individuals? An examination of the set-point theory. Am J Clin Nut 2000;72:1206-13. For more information please contact: Dr. R L Weinsier at weinsier@shrp.uab.edu. This media release is provided by The American Society for Clinical Nutrition, to provide current information on nutrition-related research. This information should not be construed as medical advice. If you have a medical concern, consult your doctor. To see the complete text of this article, please go to: http://www.faseb.org/ascn/temp/ajcn/November/(11648)weinsier.pdf
Journal
American Journal of Clinical Nutrition