Recent studies show that most adults have unexpectedly large and active deposits of a calorie-burning type of fat that biologists once thought disappeared after infancy.
The persistence of brown fat suggests a potential new strategy to fight obesity, which is epidemic in the United States and increasing rapidly in the developing world. In addition to eating less and exercising more, people may one day be able to stimulate their bodies to get rid of stored energy — in the form of ordinary fat — purely as heat.
“It is, in a sense, the discovery of a new organ,” said Sven Enerback, a researcher at the University of Goteborg in Sweden and the lead author of one of three studies appearing today in the New England Journal of Medicine.
At the moment, however, the only safe way to activate brown fat is to stay chilly, right at the verge of shivering, for prolonged periods. That reproduces the conditions that led to the evolution of brown fat — namely, life-threatening cold in babies and small furry animals that cannot put on clothes to keep themselves warm.
The three studies add to the emerging view that brown fat is involved in the body’s complicated energy balance and may play a role in diseases such as Type 2 diabetes that can arise when that balance is thrown off.
