Conventional wisdom has held that the amount of fat cells in any given person is a fixed number, but new research indicates that this may be incorrect. What is more, researchers found that the number of these cells can be reduced before weight regain by exercising.

To attain these findings, researchers fed high-fat, high-calorie diets to obesity-prone rats for a period of 16 weeks, then put them on a diet. Some of the dieting rats were allowed to exercise during this period, while others remained inactive, but all of them lost weight.

The third phase of the experiment is where researchers made their discoveries. All of the rats were allowed to eat all of the low-fat foods that they wanted, but the rats that had exercised manifested less weight gain than those that had not.

Researchers also learned that the inactive rats tended to store fats and burn carbohydrates preferentially. The opposite tendency manifested in the active rats, which contributed to their greater maintained weight loss. Another factor was the development of fewer fat cells.

The study shows that exercise is not only useful in taking weight off, but also keeping it off. A low fat diet may be useful as well, and other recent studies have suggested that the Mediterranean diet’s emphasis on fish, nuts, and vegetables makes it ideal for this purpose.