Researchers used signaling molecules to activate immune cells called macrophages that live in the unhealthy white fat tissue of mice. When the macrophages were activated, some of that white fat tissue converted to brown fat, causing the mice to burn up to 12% more energy and lose weight without moving more or eating less. (For an adult human eating 2,000 calories a day, that’s equivalent to slightly more than 200 calories.) Previously, researchers believed that when the brain’s nervous system sensed cold temperatures, it triggered the growth of warming brown fat. “But it’s not the brain that’s doing it. Instead, the brain senses the cold and talks to the immune system to make the fat,” says lead study author Ajay Chawla, MD, PhD, an associate professor of medicine at the University of California San Francisco Cardiovascular Research Institute. And now that we know how brown fat is made, we have the power to change fat tissue that stores energy into fat tissue that burns energy—at least, that is, in mice. But major health organizations like the National Institute of Diabetes and Digestive and Kidney Diseases are invested in learning how to target brown fat in humans, which could attack the root cause of the obesity epidemic, Chawla says. “The pathway in mice likely isn’t the same pathway in humans, but we’ve arrived at a proven principle, which gives us a way to go forward.” More from Prevention: 50 Ways To Lose 10 Pounds
