What Is Brown Fat and Why Do We Want It?


As the year 2020 progresses, and we continue to deal with mask mandates, a pandemic, and trying to stay healthy, it’s worth looking into how we can stimulate our bodies to be stronger and more resilient. Today, we’ll be talking about brown fat, or brown adipose tissue (BAT), what it does, and how it can help our bodies be strong and healthy.

What is Brown Fat?

Brown fat, or brown adipose tissue (BAT), is metabolically active fat that is turned on when your body gets cold. It produces heat to keep your body warm in colder temperatures. It contains many more mitochondria than white fat, which are the iron rich engines that burn calories and produce heat in brown fat. Researchers have become interested in studying it because it appears to be able to use regular body fat as fuel. As your body uses BAT to combat the cold temperatures, it burns calories (thermogenesis), creating heat without shivering. Babies, who have not yet developed the ability to shiver to maintain their body temperature, rely on the thermogenic deposits of brown fat in the neck and around the shoulders to stay warm. Initially, researchers assumed that BAT disappears during childhood, never to return. We now know, however, that adults in fact do have brown fat, and that we can stimulate our bodies to produce more.

Why do we want it?

A 2011 study found that brown adipose tissue can fuel itself with triglycerides taken directly from the bloodstream – those same triglycerides that increase the risk of cardiovascular disease and are known to increase the chances of developing metabolic syndrome leading to Type 2 Diabetes. It was also found that the BAT cells draw sugar molecules from the blood, which could also help reduce the risk for this type of diabetes.

Stimulating your brown fat is connected with acclimating to lower temperatures, which is great for those of us living in colder climates with seasonal changes. In one study, participants remained inactive for 3 hours while wearing a cold suit circulating water that was 64.4 degrees Fahrenheit. This was cold enough to lower their body temperature without causing too much shivering. Using this approach meant that researchers could be sure that the extra calories burned during the testing time were expended by the brown fat cells rather than the extra muscle action of shivering. Participants burned an extra 250 calories compared with what the would have used up during 3 hours of inactivity at warmer ambient temperatures. Though that may not sound like a lot of calories, an extra 250 per day over a period of 2 weeks would consume enough energy to allow the person to lose a pound of fat.

With this in mind, an increasing number of bio-tech companies are trying to develop ways to multiply the number of brown fat cells in the body – or even to boost their activity. They are also looking into transforming white fat cells (they really look more yellow) into tissue that behaves more like brown adipose tissue – something they call “beige” or “brite” fat.

How do we get it?

But you don’t need to rely on those bio-tech companies – you can stimulate your own body to produce more brown fat right now. Exposing your body to cool and cold temperatures helps to recruit more BAT cells. Just two hours of exposure each day to temperatures around 66 degrees F may be enough to turn some fat to brown. Taking a cold shower, cold water dousing, an ice bath, turning the thermostat down a few degrees, or going outside in cold weather are other ways to cool your body and stimulate the brown fat recruitment. As fall arrives, and the mask mandate continues, we will have as many classes outside as we can, and here in Wisconsin, the temps are in the 60’s right now – perfect for activating your brown fat cells! Additionally, there is a hormone called irisin, which is released from muscle cells after exercise, that coaxes white fat to behave like brown fat. Exercise has been show to increase UCP1 gene activity, the gene that appears to guide the conversion of white to brown fat.

More reading/sources:

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Written by Melissa Abramovich, ACE CPT, NASM CGT, AAHFRP Medical Exercise Specialist at Elite Sports Club-River Glen

Melissa Abramovich went into Personal Training and Group Exercise instruction after successfully losing 140 pounds through healthy diet and exercise. Her desire to help others drove her forward into a career helping others to make healthier choices. She is an ACE certified personal trainer and now also a Medical Exercise Specialist (AAHFRP), helping clients with a myriad of health issues at Elite Sports Clubs. She holds a Bachelor’s degree, and many group exercise related certifications as well.

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