Brown fat helps control bodyweight and may help explain why some people are more prone toward obesity than others. Brown fat is a highly thermogenic fat cell that dissipates energy as heat instead of storing it as fat. Hibernating animals have large amounts of brown fat to keep them warm during the winter. Recent studies have shown that humans also have brown fat, located mainly around the heart and spine and interspersed with white fat cells. A Dutch study found that activating brown fat lowers cholesterol, and protects the body against atherosclerosis in the coronary arteries of the heart and blood vessels of other tissues. Brown fat activation increases in response to cold environments and metformin (Glucophage), a drug used to treat type 2 diabetes.
Source: Nature Communications, published online March 10, 2015