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‘Brown Fat’ Studies Provide New Medical Insights, Hope For Weight Loss

New studies reveal that "brown fat," a type of fat scientists previously thought disappeared after infancy, can burn large amounts of calories if activated by cold temperatures. An author of one study explains the discovery and its possible medical applications.

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  • JUDY WOODRUFF:

    Well, it may sound like an oxymoron, but our next story is about what you might call "good fat." The fat in question is actually called "brown fat." Its color comes from energy-burning cells containing iron. More importantly, though, those cells burn off calories.

    For years, scientists knew babies had this kind of fat tissue, but thought it largely disappeared as infants grew older. Well, now a trio of studies published in the New England Journal of Medicine shows that brown fat is found — I think I need to take a break, and we'll be right back.

  • JUDY WOODRUFF:

    I'm sorry about that. But the fat in question, as we said, is actually called "brown fat." Its color comes from energy-burning cells containing iron. But the most important thing is those cells burn off calories.

    Now, for years, scientists knew babies had this kind of fat tissue, but they thought it disappeared as infants grew older. But now a trio of studies published in the New England Journal of Medicine shows that brown fat is found among adults, as well.

    There's a lot of attention around the findings. And to help explain it, we turn to an author connected with one of the studies. He is Dr. Ronald Kahn. He's with the Joslin Diabetes Center in Boston.

    Dr. Kahn, thank you very much for being with us.

    First of all, tell us, again, what is brown fat? It doesn't really sound like fat if it's doing good things.

  • DR. RONALD KAHN, Joslin Diabetes Center:

    Well, thank you, Judy. The issue is that the body is mostly filled with white fat. That's the kind of fat that's under our skins or inside our bellies or around our various organs. And that's most of the fat we have.

    But there is a small amount, probably just an ounce or two, of this brown fat. And it does, as you say, look actually brown because of these energy-burning mitochondria that's a part of the cell that burns the energy. And that's the part of fat that we were looking for in these studies.