New York: In what could lead to anti-obesity treatment for the elderly who may not always have the fitness to exercise, researchers have discovered that an existing drug used in transplants may help reduce food consumption and body weight.

Rapamycin, a pharmaceutical used to coat coronary stents and prevent transplant rejection, reduces obesity and preserves lean body mass when given intermittently to older rats, the findings showed.

"We need to be able to intervene with treatments for older adults. They`re going to have health care issues, and not everyone can get up and exercise," said study co-lead author Christy Carter, assistant professor at University of Florida College of Medicine.

"So if you can give them a jump-start or combine rapamycin with other therapies, you could have better health outcomes," Carter said.

Using 25-month-old rats, which are about equivalent to 65-year-old people, the researchers found that body weight dropped by approximately 13 percent after the rats were treated with rapamycin.

The drug targets how the body makes leptin, a hormone produced by fat cells that affects hunger and metabolism.

Rapamycin`s ability to stabilise the rats` leptin level made them lighter, the study said.

It worked so well that the older rats ultimately developed a lean-to-fat ratio similar to that of their younger counterparts, researchers found.

"In this case, we feel like we restored the body composition to that of a young animal," Carter said.

In a second study, researchers found that small, intermittent amounts of rapamycin produced the desired slimming effect in both young and old rats.

"One point that is common is that it seems to work better in animals, old or young, that have more fat," lead authors Philip Scarpace, professor at University of Florida College of Medicine.

The two rapamycin-related studies were published in the Journals of Gerontology as a joint effort of two research teams.