29 January 2009

Why "brown fat" may be good for you


When it comes to our food, we are used to thinking about “good fat” and “bad fat.” Unsaturated fat… promotes health and keeps cholesterol in check; saturated fat… is less healthy and should be consumed with caution; and trans fat… is practically poison, clogging the arteries and contributing to hypertension and heart disease.

But the body, too, has good fat and bad fat… When most of us think of fat tissue, what we really have in mind is white fat, which stores excess calories and tends to accumulate with too much food and too little physical activity…

Brown fat, on the other hand, is “metabolically hyperactive…” Instead of socking away stored energy for later use, brown-fat cells burn energy. With one of the highest rates of oxidative metabolism of any kind of cell in the body, and a very high density of mitochondria, “brown fat is the superathlete of mitochondrial biology…” It is the sheer density of mitochondria—the cellular powerhouses that convert glucose (blood sugar) into a form of chemical energy that the body can use—that gives these cells their brown color…

Infants have a significant amount of brown fat; it generates body heat. The medical community had long recognized this thermogenic function and wished for a way to harness it, in adults, to burn off excess calories as heat…
Recent studies have shown that some brown fat cells can persist in the body until adulthood. Researchers are now trying to stimulate these brown fat cells to proliferate as an adjunct method for weight control. Details at the link.

(The photomicrograph shows small brown-fat cells interspersed among larger white-fat cells.)

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