For years, scientists have known that rodents — and human babies — have different kinds of fat: White fat and brown fat. Brown fat burns calories; white fat just sits around. Now we know that adult humans have brown fat, too. And what if you could turn white fat into brown fat?
Well, one type of fat. Research shows adults have large, active deposits of "brown fat," a type of energy-burner once thought to disappear after infancy. Scientists hope it may lead to ways to fight obesity.