Frost bites. But it also burns fat.
This year in 2017, researchers from the University of Alaska-Fairbanks and the Center for Space Medicine and Extreme Environments followed eight competitors participating in the Yukon Arctic Ultra, “the longest and coldest ultraendurance event in the world.”
Of the four participants who were able to complete at least 300 miles of the 430-mile race, it was determined that on average they had lost three pounds overall and one pound of body fat. These competitors also saw a significant increase in irisin, the “exercise hormone,” that was not observed in studies done on irisin levels in other strength training exercise studies . (1)
This is an impressive result, but it also describes a very extreme situation that the large majority of us would not come across on a day-to-day basis. Despite this, these researchers’ studies illustrate an interesting relationship between weight loss and cold exposure that’s worth… defrosting, shall we say?
Breaking the Ice on CIT
In the cold, the body produces heat through “cold-induced thermogenesis (CIT),” which mostly describes two processes. One process, shivering, comprises the aptly-named “shivering thermogenesis” and can burn up to 100 calories every 15 minutes… that is, if you are constantly that cold and consistently shivering the whole time. (2) So, while it may seem appealing at first to replace your exercise routine with one hour of constant shivering, bear in mind that it will likely be a very unpleasant experience compared to a workout of only side planks and burpees. Only.
With that said, the action of shivering itself isn’t what researchers are looking for when it comes to fat burn; it’s the fat that acts once we start to shudder.
But First: There’s More than One Kind of Fat. Can I get a WAT, WAT?
There are many flavors of fatty tissue, but for this article we’re going to focus on white adipose tissue (WAT) and brown adipose tissue (BAT). These two types of adipose tissue compose of the fat “organ.” After all, your body fat can be viewed as one large, ever-changing endocrine organ that travels throughout your whole body and deals with appetite control, inflammation, and insulin levels, to name a few.
Humans mostly have white adipose tissue, which have larger adipose cells supplying fatty acids to other types of cells. White adipose tissue also insulates the body, buffers for “lipid energy balance,” and serves as a cuddly, cushion-y organ protector. Brown adipose tissue, its smaller, well-vascularized cousin, is not as common as white adipose tissue, but it is packed with energy-churning mitochondria and has more blood vessels traveling through it. (2)
Nice Things Come in Brown Adipose Heat Packages
Aside from being less ubiquitous, brown adipose tissue also doesn’t collect around the abdomen like white adipose tissue, which often puts one at risk to various conditions such as diabetes and cardiovascular disease. In fact, brown adipose tissue in fact appears to protect against diabetes, with leaner people having higher proportions of brown adipose tissue. And when it comes to burning calories in the cold, scientists have been looking to brown adipose tissue for it uncanny ability to cannibalize other fat cells.
Brown adipose tissue can perform the other process of “cold-induced thermogenesis: “nonshivering thermogenesis.” This means that brown adipose tissue can generate heat without causing us to shiver (although if we’re cold, we’re probably already shivering to begin with.) (3) In order to perform nonshivering thermogenesis, brown adipose tissue takes none other than more adipose to use as energy, resulting in a net loss of body fat, albeit a relatively small amount.
In young to middle-aged humans, the energy expenditure spent on nonshivering thermogenesis ranges from a few percent to 30%, and it has been demonstrated that brown adipose tissue’s impact doesn’t change with changes in diet. (5) This makes brown adipose tissue an ideal weapon against obesity that researchers have been tackling in the fight against obesity and other metabolic diseases.
WA(i)T, There’s More!
It has been recently discovered that brown adipose tissue may not be the only fat tissue with thermoregulating capabilities. White adipose cells, too, might be able to access the magical pathway of cold-induced calorie burning powers by “browning” into a brown adipose cell, a process encouraged by the hormone irisin. Released through exercise and shivering, irisin has also been shown to inhibit fatty tissue formation. (6)
Furthermore, recent studies show white adipose human cells and beige cells, or white adipose cells with some brown adipose cells mixed in, can directly respond to cold with the protein that activates brown adipose tissue’s heat generating capabilities. (7) Although this hasn’t been tested in a clinical setting, this observation could also prove useful in finding new ways to activate cold-induced fat burn, especially in nonshivering thermogenesis.
Ice-Capping It Off
It must be reiterated that shivering or standing in the cold for long periods of time, heaven forbid a 430-mile Arctic trek, would not be the most efficient nor enjoyable alternative to proper diet and exercise. Yet, there’s got to be some use for cold-exposure when it comes to burning off fat and calories, even if it’s just one extra marshmallow in your hot chocolate. In his paper on cold exposure and energy expenditure, for instance, W.D. Lichtenbelt suggests adding cold exposure training to our regime in addition to physical activity and nutrition (5). And with winter fast approaching, there is no better time to do so. Step away from that fireplace for a few moments and put on your winter coat– instead of burning wood, you’ll be burning calories outside!