Throughout the interior spaces of humans and other warm-blooded creatures is a special type of tissue known as brown fat, which may hold the secret to diets and weight-loss programs of the future. Unlike ordinary “white” fat, in which the body stores excess calories, brown fat can burn calories to heat up the body. It’s one of the things that helps keep wild critters warm on cold nights. Investigating how brown fat works in mice, a team of researchers at the University of California, San Francisco has uncovered what may be a holdover from our evolutionary past: in response to cold, tiny immune cells known as macrophages can switch on the brown fat, inducing it to burn energy to make heat.
