What Is Brown Fat? Can It Help Your Body Lose Weight?

If you are among the millions of Americans trying to become healthier and shed unwanted pounds, you probably aren’t wondering if one type of body fat is better than another. But many studies show that brown fat in your body might be a secret weapon for weight loss.

Brown fat, also called brown adipose tissue, is a special kind of body fat that helps you produce heat when you get cold. It’s why you normally don’t freeze to death when playing in the snow or walking in an icy wind.

What makes brown fat special is that it contains many more mitochondria than white fat. These mitochondria are the "engines" in brown fat that burn calories to produce heat. Numerous studies have shown that cold exposure increases the amount of brown fat that is present in the body, thereby potentially increasing the number of calories a body burns.

Can brown fat help you lose weight?

Brown fat has generated much interest among researchers because it appears to use regular body fat as fuel. This is especially true if a person is doing physical activity, because studies show exercise stimulates the hormones that activate brown fat to work its magic.

While research is ongoing, and we still need more understanding of how brown fat is activated to burn calories, scientists are hopeful. In the future it's possible that harnessing the calorie-burning power of brown fat, as well as developing medications that trigger the body’s creation of more brown fat, will be promising options for new, innovative weight-loss therapies.

But fat is fat, right?

Not exactly. Most of us have both white fat and brown fat in our bodies. Very simply, white fat stores energy and calories while brown fat burns energy and calories.

Because brown fat burns calories to generate heat, it is often referred to as the “good” fat. Infants have a lot of brown fat, but the levels of brown fat decrease as we become adults. Adults who have comparatively more brown fat tend to be younger and slender and have normal blood sugar levels.

But white fat isn’t all bad. As mentioned, it stores calories we need, helps protect our internal organs by providing a cushion, and (like brown fat) it secretes beneficial hormones (more on that below). But an excess of white fat, especially in the belly area, can cause health problems that lead to an increased risk of heart disease, hypertension, diabetes and other diseases.

Hormones and fat

Far from simply storing calories and releasing energy, both white fat and brown fat play an important part in endocrine function by producing certain hormones that help regulate glucose, cholesterol and metabolism.

There have been many studies in the recent past (mostly on mice) and more are underway (on people, too) that examine several types of hormones that are secreted by, or work closely with, fat cells — especially brown fat. Many of these hormones play key roles in maintaining health or causing disease. Here is just a sampling of some of the research.

• In a study of morbidly obese mice from the mid-1990’s, researchers discovered the mice didn’t have a hormone called leptin, which is secreted by fat cells. Without leptin to regulate their appetite, the animals were always famished and grew to nearly twice as large as control mice.
• A 2012 study found that hormones produced by the heart, called cardiac natriuretic peptides, caused regular energy-storing white fat cells to turn into energy-burning brown fat in mice. When the mice were put into a cold environment, they created more of the heart hormone, which turned on the brown fat, causing it to burn more calories.
• A study from 2016 showed that exercise may aid in weight control and fend off diabetes by improving the ability of fat cells to burn calories, by boosting levels of a hormone called irisin, which is produced during exercise. Research think irisin may help turn ordinary white fat tissue into much more metabolically active brown fat; irisin essentially helps white fat mimic brown fat’s positive effects.
• In 2018, researchers from Germany and Finland found that brown fat interacts with a gut hormone called secretin that tells the brain the body is full during a meal, which helps control food intake. Basically, when brown fat and secretin work together, the brain stops feeling hungry.

If ongoing studies show the same results in humans, fat tissue and hormones may hold a very important key to effective weight loss.

Do we know yet how to activate brown fat in humans?

While numerous studies have shown cold exposure increases the amount of brown fat that is present in the body, which translates into the body burning more calories, it’s still unclear how much cold a person has to be exposed to in order to increase his or her body’s levels of beneficial brown fat.

It might be another decade before there is concrete research showing how to increase and activate our brown fat stores with cold, but in the interim, researchers already know one thing: exercise is most likely key. If you want to start activating your own brown calorie-burning machine, start by sticking to an exercise routine.