Get Out and Get (Brown) Fat: Using the Autumn Temperatures to Your Advantage

As we move fully into Fall, the temperatures drop, daylight hours shorten, and we spend more time inside - where it’s warm, well-lit, and Netflix is available on a 24-hour basis. When we go outside, we put on more layers and thicker clothing to maintain a comfortable body temperature. But did our ancestors (at least a few thousand years ago) pop down to a Paleolithic Old Navy and pick up the latest mastodon fleece? Probably not. What they did was simple - they let their bodies self-adjust to the cold by burning an energy-rich internal fuel source. That fuel source is brown fat. And, opposed to the “white fat” that most of us are trying to lose, this brown fat is something you want.

But what are the differences between white fat (white adipose tissue, or WAT) and brown fat (brown adipose tissue, or BAT)? 

WAT is stored in various places around the body - most notably and visibly in and around the internal organs. One benefit of WAT is that it does insulate a bit, which can help retain warmth. But there are other healthier ways our fat can keep us warm. And that’s where BAT comes in.

BAT is termed “brown” because of the color given to it by the iron-rich mitochondria1 that are packed into the fat cells. These dense concentrations of mitochondria mean a dense concentration of energy. Energy your body can efficiently burn to keep warm.

Brown fat is stored around the shoulders and neck. For many years, it was thought that only infants had brown fat, which we now know is not the case. This may be because our bodies can convert, or “recruit” white fat and turn it into brown fat. This process can be accelerated via cold exposure.

And it doesn’t have to be that cold for the process to be effected. A 2015 study published in Diabetes2 indicated that as little as two hours of exposure each day to temperatures around 66˚F can convert some recruitable fat. For those hardy souls that employ cold showers or ice baths as a regular practice, this is an added benefit. If using the cold showers, try and direct the cold water onto the neck and upper back for maximum BAT development.

It has been shown that mice with higher levels of BAT burn more calories than those with lower amounts, and there doesn’t seem to be any indications that humans behave in a different way. But how do we gain or recruit more BAT? One way is through exercise. Irisin is a hormone produced during intense exercise (think HIIT or interval training) that helps to convert white fat into brown fat3. Irisin (which has many other benefits4) also inhibits the initial formation of fat cells, further increasing the ratio of WAT to BAT. Other ways to increase irisin production include saunas, supplementation with CoQ10 and Holy Basil, and a high-fat diet.

But, back to the cold. With outside temperatures dropping, this is the perfect time to take advantage of the natural environment for health improvements. Taking the dog out for a walk? Try it in a t-shirt and shorts. Shivering stimulates irisin levels, and can mimic the effects of intense exercise5. Or at the least, wear just enough to feel the cold - as stated, even a moderate drop in temperatures will cause the BAT recruitment to active. You could go for a run in the cold, or deliver a double-whammy to irisin production by doing a sprinting session every week (which is a great idea in any climate). A post-workout walk in the cold can do wonders for recovery as well. The cold helps by constricting blood vessels and flushing waste products out of the muscles, slowing down the metabolism, and reducing tissue breakdown and swelling. Although for those trying to increase muscle development, it’s worth noting that some research seems to indicate that icing muscles soon after maximum effort (i.e. a one-rep max situation) curbs inflammation, and inhibits the growth of muscle fiber and muscle regeneration.

Another excellent benefit to cold exposure is the effect it has on sleep quality (see our previous post, “Sleep. How to get more sleep, get better sleep, and keep the sleep you get.” Our bodies naturally drop in core temperature when we fall asleep. Kick-starting the process via cold exposure can help us fall asleep faster and more deeply.

One catch to the lower temperatures - our appetite tends to increase, which can result in a higher caloric intake. Taking a walk outdoors before eating may help to counteract that increase.

Bottom line, cold exposure has many benefits. And again, you don’t need to go jump in a local lake to enjoy them (although it certainly wouldn’t hurt - much). You have the ability to decide what your comfort levels are, but we highly recommend pushing out of your comfort zone a little bit at a time. Start finishing your hot shower with 5 seconds of cold water. The next week, make it to 10 seconds, the next, 15. Soon you’ll be under the cold for minutes at a time, recruiting BAT like crazy, and have the best sleep of your life. What have you got to lose? 

Citation Links:

1Mitochondrion - Wikipedia 

2Brown and Beige Fat: Molecular Parts of a Thermogenic Machine Diabetes 2015;64:2346–2351 

3Is irisin a human exercise gene?Nature. 2012 Aug 30 The 9+ Benefits of Irisin And How To Increase It Naturally To Burn Fat, You Could Exercise … or Shiver

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Published on November 9, 2019.