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Make Heat, Not Fat

Jealous of those skinny people who eat constantly but seem to just burn it off? Now scientists have discovered a way to mimic their metabolism. By introducing a protein that turns fat to heat, they kept well-fed mice slim.

Mice keep warm by converting fat from deposits called brown adipose tissue into heat. A protein called Ucp stokes this biochemical furnace--inspiring researchers to wonder whether Ucp could help obese people burn off extra calories instead of storing them as fat.

To test the idea, a team led by physiologist Clay Semenkovich of the Washington University School of Medicine in St. Louis, Missouri, engineered mice to produce Ucp in skeletal muscle, in addition to the Ucp normally produced in brown adipose tissue. When fed the same high-fat diet, mice with extra Ucp ate just as heartily as their normal counterparts, but weighed up to 32% less. Moreover, the Ucp mice showed other signs of good health: They had lower levels of sugars and lipids in their blood, and they were less likely to develop symptoms of diabetes, the researchers report in the October issue of Nature Medicine.

The study "is a proof of principle" that the Ucp protein could potentially be used to fight obesity in humans, says Leslie Kozak, a molecular geneticist at the Pennington Biomedical Research Center in Baton Rouge, Louisiana. He points out that the altered mice didn't suffer from elevated body temperatures, a deadly side effect of other proteins that turn fat into heat.

Related sites
Clay Semenkovich's Web site