According to researchers from the University of Colorado Denver, burning fat first and storing carbohydrates for use later in the day slows weight regain and may minimize overeating by inducing a feeling of fullness to the brain.
They insist that exercise prevents the increase in the number of fat cells that occurs during weight regain.
This discovery also challenges the conventional wisdom that the number of fat cells is set and cannot be altered by dietary or lifestyle changes.
These coordinated physiological changes in the brain and the body lower the 'defended' weight, that is, the weight that our physiology drives us to achieve, and suggest that the effects of exercise on these physiological processes may make it easier to stay on a diet.
During the study, the researchers used obesity-prone rats. For the first 16 weeks, the rats ate a high-fat diet, as much as they wanted, and remained sedentary.
They were then placed on a diet. For the following two weeks, the animals ate a low-fat and low-calorie diet, losing about 14pct of their body weight.
The rats maintained the weight loss by dieting for eight more weeks. Half the rats exercised regularly on a treadmill during this period while the other half remained sedentary.
The findings revealed that exercising rates regained less weight and burned more fat early in the day, and more carbohydrates later in the day.
It reduced drive to overeat and enhanced the ability to balance energy intake with energy expended.
The team will do further research to demonstrate that exercise is, indeed, preventing the formation of new fat cells early in relapse and not simply altering the size of pre-existing fat cells.
The study appears in American Journal of Physiology.