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Know someone with a big gut and skinny legs?

Why “they’re probably in trouble,” according to a fat expert.

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Pretend for a moment you could choose where to store the extra calories you’ve eaten. Would you prefer your thighs or your belly?

One place boosts your odds of losing those extra pounds. But it also increases the negative impact of the weight on your health.

Spoiler alert: If you could choose (and you can’t, really), pick your thighs.

The body fat expert explains why.

“We know that if people gain leg fat, they actually gain new fat cells, so they’re sort of stuck with new fat cells,” says Michael Jensen, director of the Obesity Treatment Research Program at the Mayo Clinic in Minnesota.

That’s not true for belly fat.

“At least with modest weight gain, almost all the weight gain in upper body fat is an increase in fat cell size,” says Jensen. “Each fat cell just agrees to store a little bit more”

Here’s the good part.

“That makes upper body fat easier to lose than thigh fat,” Jensen says.

For example, he and his colleagues fed 23 lean men and women an extra 400 to  1,200 calories a day as ice cream shakes, Snickers bars, and Boost Plus energy drinks. After two months, their weight jumped by about eight pounds.

Then for the next two months, the participants cut their calories and boosted their exercise and lost an average of six pounds. What remained was mostly extra leg fat.

“When we look at the loss of that gained weight, upper body fat goes away first and leg fat goes away last, because you created a whole new set of cells there in the legs,” says Jensen. “Once you have a new fat cell, it’s very hard to get rid of it, so it’s the last place you will lose weight.”

And it’s not just a few cells. In another study, Jensen found that 3½ pounds of new leg fat created roughly 2.6 billion new fat cells within two months.

Sure you need that cookie?

But upper body fat cells can’t keep getting bigger and bigger.

“Your fat cells can only get so big,” explains Jensen. “From the smallest fat cell to the biggest fat cell is only about a four-fold increase. And we all know people who have gained more than four times as much fat as they had when they were skinny. So eventually, you have to start recruiting new fat cells.”

Apparently, we all have pre-fat cells (called pre-adipocytes) that are just waiting to be pressed into service whenever we need them. Wonderful.

Storing more fat in your legs is actually healthier.

“People who gain predominantly leg fat tend to have a much better metabolic profile than people who put on a lot of abdominal fat,” notes Jensen. “They’re less likely to get diabetes, less likely to get high cholesterol and high triglycerides, and less likely to get hypertension and sleep apnea.

“My biggest worry is when a patient comes in with a big gut and skinny legs,” he adds. “I know they’re probably in trouble.” Sound like someone you know?

It’s not clear why upper body fat—especially the deep-belly visceral fat—is worse. A possibility: visceral fat cells may send more fat to the liver.

Or a generous layer of visceral fat may be a sign that your subcutaneous fat is faulty.

“One speculation is that people gain visceral fat because the subcutaneous fat in their abdomen and thighs is not doing its job,” says Jensen. “Its job is to sequester fat from the excess calories you ate so that it can’t harm your lean tissue. “

What you don’t want.

And if the subcutaneous fat can’t do its job, the fallback job goes to the visceral fat. And if the visceral fat can’t do its job, the fat starts building up in your liver and muscles and other places where you really, really don’t want it.”

Why?

“Those organs can’t package fat in the safe triglyceride form very well,” explains Jensen. “As a result, the fatty acids—the individual components of triglycerides—can interfere with cell function.” You might end up with non-alcoholic fatty liver disease, for example.

“It’s as though you kept putting gas in the gas tank when it’s full and now it’s running all over the side of your car,” says Jensen. “It’s a bad situation.”

A better strategy: Not eating those extra calories in the first place so that your body doesn’t have to stash it somewhere.

 

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