Washington - Researchers have figured out how to remove fat from one part of the body and make it grow in another part -- at least in mice -- and say their findings could benefit health as well as beauty.

Their findings also shed light on how and why stressed-out people so often gain weight.

"We don't think this is something that would be used for gross obesity, but for reshaping the body for use with pockets of fat ... that would be all very good," said Dr. Zofia Zukowska of Georgetown University Medical Center in Washington, who led the study.

Their findings are based on a naturally produced chemical messenger or neurotransmitter called neuropeptide Y, or NPY -- long linked with appetite, weight gain and obesity.

Zukowska said her findings in mice suggest that NPY helps make some body fat more dangerous than other kinds. Controlling it could help slow some of the more dangerous side effects of obesity such as heart disease and diabetes, her team reported in the journal Nature Medicine.

Manipulating NPY offers a new tool for plastic surgeons. "You could take the fat from your buttocks and put it in your breasts and cheeks," she said.

NPY attaches to a receptor, a molecular doorway, in fat cells that is called neuropeptide Y2 receptor, or Y2R. It activates fat cells and some of cells in the blood vessels found in fat tissue.

Oppressive Commute

For the research, Zukowska's team first tried to stress mice in a way that would duplicate human life.

They made them stand in cold puddles -- akin to riding a bus with wet feet in the winter. They also put the mice with aggressive mice that might act similarly to an angry human boss.

Half the stressed mice got a normal mouse diet and half got a high-fat, high-sugar diet. "What I like to call the American diet," Zukowska said.

The stressed mice given a normal diet lost weight. Those on the "American" diet gained weight, more weight than would be expected given how much they ate. And their bodies were producing extra NPY.

Zukowska believes that NPY helps the body lay down fat, rich in blood vessels. "It is the bad kind of obesity because it leads to diabetes, hypertension, cardiovascular disease and strokes -- what we call metabolic syndrome," she said.

When the researchers injected a drug that blocks Y2R -- the doorway NPY uses to get into cells -- the mice lost 40 percent of their belly fat. Not only that, but signs of diabetes and other ill effects disappeared.

"It had a profound effect on overall metabolism," Zukowska said.

Her team also made NPY into a slow-release pellet. When they placed this pellet under the skin of thin rhesus monkeys, they grew pockets of fat around the pellets. Such treatments may help replace the fat lost in people's faces as they age.

They used a drug made by privately owned Boehringer Ingelheim to do this, and have a license for its use in this way, but Zukowska said her team may look for other drugs that have the same effect. It has not yet been tested in humans.

Zukowska noted that some clinics claim to already offer such treatments, but said they use bile acids that kill tissue and may cause infection. "There isn't anything on the market right now that could be used to melt the fat that is scientifically proven," she said.