May 7 (HealthDay News) -- Older, overweight women who diet do not experience reduced physical function and should feel free to try to lose weight by reducing their calorie intake, U.S. research shows.

"Our results suggest that losing weight through calorie cutting won't lead to increased disability in older women," lead researcher Dr. Jamehl Demons of Wake Forest University Baptist Medical Center, said in a prepared statement.

When older, overweight women diet they may often gain back some of the weight. But they are still better off than before, noted Dr. Mary F. Lyles, also at Wake Forest and the lead investigator of a second project that examined how dieting affects body composition.

The findings of the two projects -- both part of the larger Diet, Exercise and Metabolism in Older Women (DEMO) study -- were to be presented Friday at the annual meeting of the American Geriatrics Society in Seattle.

Weight loss results in a reduction of both fat and muscle, and people naturally lose muscle mass and physical function as they age. This has led to questions about the safety of older adults dieting in order to lose weight.

Demons' project looked at 23 obese, postmenopausal women, average age 58, who were put on a calorie-reduced diet for five months. They lost an average of 25 pounds, with muscle representing about 35 percent of that weight loss.

"Despite the large amount of muscle loss, their aerobic fitness and their ability to rise from a chair showed a trend toward improvement," said Demons, an assistant professor of internal medicine-gerontology. Furthermore, "Their strength and walking speed did not change. This suggests that their weight loss through dieting wouldn't be expected to lead to increased disability," the researcher said.

Lyles' project looked at body composition before and after 30 women were on a five-month calorie-reduced diet. During that time, the women lost an average of 25 pounds (about 68 percent fat and 32 percent muscle). A year later, the women had regained an average of 11 pounds (about 73 percent fat and 27 percent muscle).