What Does Your Fat Mean?

PHILADELPHIA (CBS) -- People who have complained about having thunder thighs now have a reason to celebrate. New research says fat in the thighs is different from belly fat, and better! Medical Reporter Stephanie Stahl has more details.

Researchers compared thunder thighs to potbellies. Turns out it's not the same kind of fat. This was a different kind of diet study where instead of wanting to lose weight, people packed on the pounds and gorged on goodies.

Candy bars and ice cream, 28 people in the Mayo Clinic study loaded up on fattening treats for eight weeks. Researchers were looking at how body fat grows.

"We used to think that we had a certain number of fat cells you were born with, and that number stayed pretty much the same your while life, just those fat cells would swell or shrink depending on your weight," said Dr. Michael Hirt, an Internist.

Now researchers have a new understanding of fat.

That might help explain why people like Judi Goldstein tend to have certain trouble spots repeatedly.

"I don't gain it in my stomach. I don't gain it in my waist. It's always in my hips and my thighs," said Judi.

The Mayo researchers have discovered that the kind of fat in the lower body is different from what accumulates around the waist. The difference is more fat cells versus fat that grows in size.

"Now we know that fat cells actually can multiply in your thighs, but in your belly they just sort of expand and shrink," said Dr. Hirt.

So for Judi and others who gain weight in their hips and thighs, the number of fat cells actually increase and that decreases the risk for metabolic diseases, like diabetes. While fat around the waist just grows and shrinks, and that's more dangerous.

"The most important type of fat to target is your belly fat because that's the fat that's associated with diabetes and heart attacks and strokes and high blood pressure," said Dr. Hirt.

The people in the study who pigged out for two months gained about eight pounds of body fat, but it was quickly lost once they went back to regular eating.

Reported By: Stephanie Stahl, CBS 3