A thermograph of brown-like fat implanted in anesthetized animal at room temperature. The implant, shown in area A, is significantly warmer compared with the control region in area B. Photo by Kevin Tharp and Andreas Stahl/University of California Berkeley

BERKELEY, Calif., Aug. 20 (UPI) -- Researchers grew "healthy" beige fat and injected it into mice, finding that it slashed the amount of weight they gained while on a high-fat diet, as well as lowering their levels of blood glucose and circulating fatty acids.

Beige fat is similar to the better known energy-burning brown fat, but is produced within white fat after exposure to cold and other situations. Brown fat serves as a heat generator, burning calories along the way.


"This is figuratively and literally a hot area of research right now," said Andreas Stahl, an associate professor of nutritional sciences and toxicology at the University of California Berkeley, in a press release. "We are the first to implant in mice an artificial brown-fat depot and show that it has the expected effects on body temperature and beneficial effects on metabolism."

Previous research suggested stem cells take growth cues from their environment, becoming fat in soft environments and bone in more stiff environments. With this in mind, the researchers took stem cells from white fat and added them to a hydrogel containing protein sequences associated with brown-fat growth and function, injecting the gel under the skin of mice before it thickened.

Initially, the researchers noted that the internal temperatures of the mice were on average half a degree warmer than those that didn't receive an injection. The mice also were put on a high-fat diet during the experiment. Three weeks in, the mice that received the injections had gained half as much weight as the other mice, and they had lower blood glucose and circulating fatty acids in their bodies.

"This is a feasibility study, but the results were very encouraging," Stahl said. "It is the first time an optimized 3D environment has been created to stimulate the growth of brown-like fat. Given the negative health effects of obesity, research into the role of brown fat should continue to see if these findings would be effective in humans."

The study is published in Diabetes.

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