ARI SHAPIRO, host:
Some studies coming out today finds that one kind of fat tissue could actually help people lose weight. It's called brown fat, and the studies say it burns off calories quickly, unlike ordinary white fat that stores up calories. Most adults have some hidden pockets of this good fat, and NPR's Richard Knox reports these new findings may lead to new ways to avoid obesity.
RICHARD KNOX: Brown fat looks different from the yellowish-white stuff we think of when we hear the word fat. That's because it's packed with little energy factories that give it a dark color. For decades, scientists have been fascinated by the unique properties of brown fat.
Mr. FRANCESCO CELI (National Institutes of Health): This is probably the only tissue whose purpose is to burn energy. In other words, just to produce heat.
KNOX: That's Francesco Celi of the National Institutes of Health. Like other scientists, he used to think that brown fat was only important to human infants. They can't shiver or move around much, so they need brown fat to keep warm. But everybody thought that people lose brown fat as they grow up. The new studies show, without doubt, that adults have it too.
This is good news, because brown fat, like good cholesterol, is healthy stuff, says Aaron Cypess of Joslin Diabetes Center in Boston.
Mr. AARON CYPESS (Joslin Diabetes Center): We call brown fat good fat, because as far as we know, it does only good things. It is able to take excess calories within the body and burn them up, therefore able to reduce obesity.
KNOX: Cypess and his colleagues examined nearly 2,000 high-tech scans, which highlight tissue that's metabolically active. They found deposits of brown fat in almost everybody. Older people have less, so do obese people, but virtually everybody has some.
Meanwhile, other teams were also finding brown fat in adults. A group at the University of Maastricht in Holland decided to do scans on a couple dozen people after putting them in a chilly room for a couple of hours. They figured that low temperature - about 61 degrees - would activate the brown fat, just as it does in babies, so it would start producing heat.
Mr. VAADER VON MARTIN LICTENBELT(ph) (University of Maastricht): And indeed it worked. We were very surprised to see that much brown fat as we did, and in so many people as we did.
KNOX: That's Vaader von Martin Lictenbelt, who led the team. He wonders if people trying to lose weight might find it easier if they just turned down the thermostat.
Mr. LICTENBELT: Yes, turning down the heater in the house and then you start heating yourself.
KNOX: With your own activated brown fat. There may be something to that. A Scandinavian team reports that putting research subjects in a chilly room for a couple of hours revved up the calorie-burning capacity of their brown fat cells 15 fold. Cypess, the Boston researcher, thinks turning down the heat deserves a closer look as a diet strategy.
Mr. CYPESS: What we need to find out is how many more calories do you burn off if you sit at a home at 60 degrees Fahrenheit versus 72 versus 80. And if in fact it looks like you're burning off way more calories, then that might be a very simple way to lose weight and help your health.
KNOX: But what if people compensated for being chilly by eating more? That possibility has Cypess and others looking to drugs as a way to rev up those brown fat cells. It might not take much.
Mr. CYPESS: We calculate that if you have three ounces' worth, that will be enough to burn up 400 to 500 calories per day.
Mr. CYPESS: Yeah.
(Soundbite of laughter)
KNOX: Clearly, those brown fat cells are powerhouses at burning calories. All three research papers appear in this week's New England Journal of Medicine.
Richard Knox, NPR News, Boston.