Fighting Fat With Fat Fat is fat, right? There’s belly fat, leg fat, even neck fat. But when all is said and done, fat is fat. And the less of it you have the better. Except…for brown fat. Unlike white fat cells that store energy, brown fat burns energy. It’s typically found in hibernating animals and human babies. When it’s cold, brown fat burns calories, which releases heat to keep the body warm. Until recently, scientists thought that as people grew, their brown fat melted away. But it turns out that human adults have some brown fat, too. This discovery is pretty new, so scientists are still figuring out what it means, and whether brown fat can somehow be used to help people lose weight. But there are some promising signs. Studies have shown that lean people tend to have more brown fat, and that the fat is most active in cool temperatures. So it’s possible that people become obese partly because they don’t have enough brown fat to burn excess calories. Scientists are now working on ways to help obese bodies create more brown fat. Experimenting with proteins, Harvard researchers have managed to ramp up production of brown fat cells in mice. Brown fat is no miracle cure for obesity. It’s not clear whether having more brown fat actually does or could lead to more weight loss. And scientists are a long way from being able to increase brown fat stores in people. But at the very least, we’ve learned that not all fat is necessarily bad. Down the road, brown fat may help make people’s lives better.