Brown Fat continued...
Brown fat is now thought to be more like muscle than like white fat. When activated, brown fat burns white fat.
Although leaner adults have more brown fat than heavier people, even their brown fat cells are greatly outnumbered by white fat cells. "A 150-pound person might have 20 or 30 pounds of fat," Cypess says. "They are only going to have 2 or 3 ounces of brown fat."
But that 2 ounces, he says, if maximally stimulated, could burn off 300 to 500 calories a day -- enough to lose up to a pound in a week.
"You might give people a drug that increases brown fat," he says. "We're working on one."
But even if the drug to stimulate brown fat pans out, Cypess warns, it won't be a cure-all for weight issues. It may, however, help a person achieve more weight loss combined with a sound diet and exercise regimen.
White fat is much more plentiful than brown, experts agree. The job of white fat is to store energy and produce hormones that are then secreted into the bloodstream.
Small fat cells produce a "good guy" hormone called adiponectin, which makes the liver and muscles sensitive to the hormone insulin, in the process making us less susceptible to diabetes and heart disease.
When people become fat, the production of adiponectin slows down or shuts down, setting them up for disease, according to Fried and others.
Subcutaneous fat is found directly under the skin. It's the fat that's measured using skin-fold calipers to estimate your total body fat.
In terms of overall health, subcutaneous fat in the thighs and buttocks, for instance, may not be as bad and may have some potential benefits, says Cypess. "It may not cause as many problems" as other types of fat, specifically the deeper, visceral fat, he says.
But subcutaneous fat cells on the belly may be another story, says Fried. There's emerging evidence that the danger of big bellies lies not only in the deep visceral fat but also the subcutaneous fat.