Can Brown Fat Fuel Your Fat-Fighting Furnace?

For body fat, color matters
thermometer and sun

Most of the fat in your body is like a storage unit: When you eat a cheeseburger, the excess calories move in and stay until you need them for fuel.

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But what if you could turn that storage unit into a furnace — and burn the fat for heat?

That’s what a special kind of fat — brown fat — does.

All of us have at least two kinds of fat naturally. White fat is the storage unit, and brown fat is the furnace room, says Jonathan Mark Brown, PhD, a researcher in Cleveland Clinic Lerner Research Institute’s Department of Cellular and Molecular Medicine. Now, researchers are trying to see if they can reduce the white fat by stoking the fire inside brown fat and expanding its reach inside white fat, a process researchers call “beiging” fat.

“This is really a renaissance of thinking on brown fat,” Dr. Brown says. “There’s little doubt that activating brown fat can burn a lot of energy. And there’s good evidence in animal studies that if you ramp up brown fat activation, you can protect against obesity and its comorbidities, like cardiovascular disease, diabetes and cancer.”

Baby brown fat lives on

Scientists have known about brown fat for a century, but it wasn’t until earlier this century that they discovered it survives past childhood. Brown fat burns other fat to create heat for a very good reason: When you’re born, your body can’t efficiently warm itself by shivering. So brown fat’s heating mechanism is the only one you have as a baby.

For a long time, researchers thought people lost brown fat as we aged. But in 2009, several studies published in the New England Journal of Medicine discovered brown fat below the shoulder blades and in the upper torsos of adults. The race to find the best ways to stoke brown fat began.

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Since then, scientists have been trying to learn more about brown fat, to get it to burn more energy and to activate or create beige fat in white fat deposits.

“This is really a renaissance of thinking on brown fat. There’s little doubt that activating brown fat can burn a lot of energy.”

Research ramps up

Brown notes there’s early evidence that brown fat isn’t as active in obese people as it is in others. It could be, he says, that lower brown fat activation leads to weight gain — or the weight gain itself could somehow disarm brown fat’s furnace. If researchers can find a way to intervene, it could ease the weight loss journey for millions of Americans.

Researchers also are trying to expand brown fat’s reach, either by converting white fat cells to brown fat-like cells or by making brown fat grow. Two 2012 studies found that the hormone irisin, normally released after exercise, can make white fat behave more like brown fat.

Yet other research shows that cold temperatures may stimulate brown fat naturally. A 2012 study showed that when people soaked in a bath calibrated to 64.4 degrees Fahrenheit daily, they burned an additional 250 calories a day for two weeks. Another study, released last year, found that men who sat in 63-degree rooms for two hours a day for six weeks burned 289 more calories than those who didn’t.

The results are promising—but don’t reach for your thermostat just yet, Brown cautions.

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The jury is still out

Dr. Brown points out that most of the research so far has been among small groups of men or animals, meaning we don’t yet know how it will translate to the population as a whole. It’s also one small piece in a much larger obesity puzzle.

“My opinion on this is that the jury is still out,” Dr. Brown says. “Obesity is a very complicated condition, driven by lots of different genes and lots of factors in our environment.”

In the next five years, Brown says he expects the research to get more exact and to include more human studies—an exciting prospect. In the meantime, though, he suggests you do what has already been proven to work: eat a healthier diet, including plenty of fruits and vegetables, and get the benefits of brown fat by exercising.

“It’s important to find something that activates brown [fat] tissue but avoids off-target effects on other organs,” he says. “But the age-old philosophy of fewer calories in and moving more is probably still the No. 1 way to combat obesity.”

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