 Emerging research into a rare kind of fat cell known as brown fat may lead to new medical interventions to fight obesity. Researchers have known for some time of the existence of brown fat in newborn mammals. Unlike the more common white fat, which stores energy, brown fat actually releases energy in order to help heat the body. With the recent discovery that some brown fat cells also exist in adult humans, researchers have begun to wonder whether it might be used to help obese people lose weight. In two studies recently published in the journal Nature , researchers explored the bodily mechanisms that regulate brown fat. In the first, a team of researchers from the Dana-Farber Cancer Institute in Boston built on its previous finding that a specific gene transcription factor known as PRDM16 helps regulate the activity of brown fat cells. When the researchers removed that transcription factor from immature brown fat cells, the cells immediately turned into muscle. 'What we show in this paper is kind of a big shock,' researcher Bruce Spiegelman said. 'We show that brown fat is derived from a muscle-like cell, and that brown fat and white fat are completely different.' Previously, the same team showed that the addition of PRDM16 could cause white fat cells to turn into brown fat. They are now investigating whether a pharmaceutical drug could be used to stimulate the activity of PRDM16 and encourage the body to make more brown fat. In a second study, researchers from the Joslin Diabetes Center, also in Boston, injected a bone growth protein called BMP-7 into the bodies of mice by means of a virus. The mice that had been injected with BMP-7 subsequently developed more brown fat cells and gained less weight than mice that had not been injected. The same result occurred when researchers transplanted BMP-7-treated immature brown fat cells into adult mice. Sources for this story include: www.reuters.com . 