Everything You Need to Know About Brown Fat

High-intensity exercise burns calories


We want to lose it. We want to burn it. We want to trim it. We want to melt it off.

But fat isn’t a catch-all evil waiting to gift us with a few more doughy pounds. Recent research shows not all fat is created equal, and in fact, some fat is good for us.

Yes, in our bodies we have fat that helps us lose fat. This miracle flab is called brown fat. Here’s everything you need to know about it. 

What is brown fat?

The typical fat that clings after a few extra donuts is called “white fat.” It’s the stuff we’ve come to know and hate, and its main purpose is to store energy, says Labros Sidossis, a researcher and professor at the University of Texas Medical School.

Brown fat, on the other hand, burns energy at an astonishing clip. It’s packed with mitochondria—the power sources for our cells—which give it a darker shade. While regular white fat passively stores energy from our excess consumption, brown fat actually burns energy.

“We thought for many, many years only small animals and babies had brown fat, and then it would disappear,” Sidossis says. 

But over the past decade, researchers like Sidossis discovered that brown fat doesn’t completely disappear in adult humans, and that it in fact may play an important role in boosting our metabolisms. “The reason it looks darker is because it has many more mitochondria, just like small organs and muscles, and it also has many blood vessels,” Sidossis says. 

What does brown fat do?

Babies and small animals accumulate a large amount of brown fat because it helps regulate the body’s core temperature by producing heat. But in order to produce that heat it has to burn energy, which is why brown fat might actually be good for us.

According to new research from Sidossis and his colleagues, activated brown fat can increase our metabolism by 15%. For a typical adult that means brown fat can burn up to 300 calories a day. 

The best part? You don’t even have to move.

“To burn 300 calories you have to run three miles. If brown fat is activated, it will do the same if you just watch T.V.,” Sidossis says. “This is important for someone who is conscious about losing weight.”

In his latest research, Sidossis also found that brown fat helps regulate blood sugar, an important finding for diabetics. 

How much of your fat is brown fat?

While we can accumulate a large and unhealthy amount of white fat, our bodies only store a few grams of brown fat at the base of our neck—or so we thought. The proportion of brown fat to white fat might not be so disproportionate after all. In fact, we’ve got about 3 times more brown fat than previously believed, accord to brand new research from the Technical University of Munich (TUM).

In the study, published in the Journal of Nuclear Medicine, researchers analyzed about 3,000 PET scans from 1,644 men and women to pinpoint and visualize metabolic activity in the body. The researchers concluded new drugs developed for obesity and diabetes that activate brown fat tissue are expected to be more effective as a result.

How do I activate brown fat?

The latest Munich research shows some people activate brown body fat more than others and might even have more of it in the first place. Intrinsically, women have more active brown fat than men. And thinner, younger people have larger proportions of brown fat. 

Two ways to activate brown fat’s energy burning potential: exercise and cooling down.

In Sidossis’ study, participants who stayed in a mildly cool room—between 60 to 70 degrees—experienced the positive effects of brown fat because it reacted to the change in temperature.

“When we are exposed to cold, our body needs to do something to keep us warm and the first thing it does is produce heat,” Sidossis says. “For brown fat to produce heat it needs fuel.”

The research is so new that Sidossis is unsure why exercise also activates brown fat, but he says the best way to take advantage of it is to either stay cool or get active.

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