Weight regain after dieting can be avoided with low-intensity exercise
Weight regain associated with metabolic changes that occur after dieting can be avoided through a program of low-intensity exercise, according to a study by van Aggel-Leijssen et al., published in the American Journal of Clinical Nutrition. While dieting, men who did not exercise lost about the same amount of fat mass as the group that exercised. However,2 weeks after returning to an energy-balanced diet at a reduced weight, the non-exercising group had a lower rate of fat metabolism, a change that could predispose them to weight gain.
Forty obese men averaging 39 years old participated in an energy restriction program for 10 weeks at Maastricht University in the Netherlands. The "diet only" group followed a protein-enriched low calorie liquid formula diet for 10 weeks; at the same time the "diet-plus-exercise" group added a low-intensity exercise training program 4 times a week during the diet, and for 2 weeks afterward. Each exercise session consisted of cycling, walking or water jogging at 40% of aerobic capacity. The two groups of men lost an average of12.6 and 12.5 kg. of fat mass respectively, and changes in body mass index and postdiet aerobic capacity were similar between the two groups. The respiratory exchange rate (RER), a gauge of fat metabolism, was determined before and 2 weeks after the diet by measuring carbon dioxide production and oxygen consumption while the men cycled on an ergometer at 50% of their aerobic capacity. In the diet-only group, RER was lower than it had been before the diet, whereas in the diet-and-exercise group, changes in RER did not differ significantly before and after the diet. The administration of propranolol, a drug that stimulates lipid metabolism, produced less of a response in the diet-only group 2 weeks after the diet than it had before the diet, indicating a decline in fat metabolism. On the other hand, in the diet-plus-exercise group, the response to propranolol was similar both after the diet and before, indicating that the prediet fat oxidation rates had not changed.
The results of the study suggest that low-intensity exercise training during weight loss maintains fat oxidation by maintaining the sensitivity of the central nervous system, which tends to be reduced after weight loss alone. The effects of continuing exercise training in the long term on sustained weight loss merit further investigation.
van Aggel-Leijssen, Dorien P.C., et al. Short-term effects of weight loss with or without low-intensity exercise training on fat metabolism in obese men. Am J Clin Nutr;73:523-31.
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/ajcn/March/11710-Aggel-Leijssen.pdf