By Dr. Farooq Achmad

It is known since long that there are two types of fat found in humans; white and brown. White (or yellow) is the form of fat that everybody knows. Brown is the one less people know about. An infant has predominantly brown fat in his body. However, as he grows up, the brown fat gradually changes into white.

The striking difference between the two is not in their colors but in their impact on body weight; while the excess white fat causes obesity, the brown does just the opposite: it burn calories and hence contributes to reduce obesity! Although the primary function of brown fat in infants and rodent seems to be generation of heat, it indirectly helps reduce obesity by way of burning body’s energy fuel.

Until recently, adults were believed not having brown fat in their bodies. New findings, with hi-tech PET-CT Scan however suggest the presence of brown fat in adult as well. PET-CT Scan, which is best at pin-pointing any biochemical activity going on anywhere in the body, has helped researchers discover the minimal hidden depots of brown fat in adult.

Not only brown fat has been shown to be present in adults, but studies also point out that when it is cold, it sucks white fat out of its depots and burn it out as fuel.

The best evidence for the effects of brown fat is from earlier studies in mice, says Leslie P. Kozak, a professor of molecular genetics at the Pennington Biomedical Research Center of Louisiana State University.

In a recently study, Dr. Kozak put mice predisposed to obesity in a cold room, 41 degrees, for a week. The animals activated their brown fat. As a result, they lost 14 percent of their weight, which constituted 47 percent of their body fat, while eating a high-fat diet with two and a half times more calories than they had consumed at room temperature.

"That’s just by going out in the cold, without any drug treatment," Dr. Kozak said. But, he cautioned, mice, small animals with a comparatively huge surface area, are easily chilled. "Put the mouse in the cold," he added, "and it becomes a heat producing machine."

Another study by Dr. André Carpenters, an endocrinologist and his co-researchers at the University of Sherbrooke in Quebec, reports that brown fat can burn ordinary fat and that glucose is not a major source of fuel for these cells.

“We have proof that this tissue burns calories — yes, indeed it does," Dr. Carpentier said. “But what happens over the long term is unknown.

"The thing about brown fat is that it takes a very small amount to burn a lot of energy," says another researcher, Dr. C. Ronald Kahn, head of the section on obesity and hormone action at the Joslin Diabetes Center in Boston.

Exposure to severe cold can likely have harmful effects. Researchers are striving to find out some safe way to stimulate the dormant brown fat: "If a drug that stimulates brown fat could be developed, said Dr. Claude Bouchard of the Pennington Biomedical Research Center, it would be the first obesity drug to affect energy expenditure rather than appetite."

Readers please be informed that although these initial findings about the positive role of brown fat as well as the discovery that cold environment can stimulate brown fat are very encouraging, researchers think much more research needs to be done before they can reach at a definite conclusion.

Hence our advice: DON’T START TRYING IT RIGHT AWAY!