The Paleo/Primal community has been abuzz with talk about cold plunges and brown adipose tissue. Mark Sisson’s site covers some of the interesting findings from the effects of cold exposure in conducting a quantified self type of experiment.
Tim Ferriss, in his 2010 book The Four Hour Body, describes a method of weight loss that he called Cold Therapy that uses ice packs on the upper neck that helps to enhance metabolism. His experiments ran the gamut from full ice baths, to cold showers, to walking in the cold, to simple ice packs, to sleeping in your birthday suit. The crazy thing is that Scottish showers, and other methods of Cold Therapy, have been used by people throughout history for health benefits. The modern conveniences of hot water have mostly removed the positive consequences of cold therapy.
After some of my own experimentation in early 2011 with the various types of Cold Therapy outlined in 4HB, I set out to determine what caused this phenomenon. My research has led me mostly to two items:
- The physiologic responses caused by contact with cold
- And potentially more important, the presence of brown adipose tissue
I’ll cover each item individually.
The natural response to cold is to maintain homeostasis. For your body to perform correctly your body really needs to be right at 98 degrees. In response to cold arteries and veins will constrict to reduce heat loss caused by the additional skin surface area in the extremities. Skeletal muscle will also begin to shiver which expends energy and warms up the body. This is boring almost common sense kind of stuff. The next section is the more interesting one.
Brown Adipose Tissue
Brown adipose tissue, also known as Brown Fat, is a specialized type of muscle tissue commonly found in infants and hibernating mammals. Brown fat is a misnomer since is actually closely related related to skeletal muscle and is brown because of its high concentration of mitochondria. If you’ve forgotten high school science, mitochondria are basically the power plants of cells. They take “fuel” and turn them into energy that the body can use in the form of ATP.
Brown fat in hibernating mammals is used to help regulate energy expenditure during hibernation. In a human infant brown fat helps babies to regulate body heat due to their increased risk of death from hypothermia since the high concentration of energy producing mitochondria creates heat as a byproduct of the process. Why would infants be at a high risk of hypothermia? Here is a list of reasons:
- The higher ratio of body surface (proportional to heat loss) to body volume (proportional to heat production)
- The higher proportional surface area of the head
- The low amount of musculature and the inability or reluctance to shiver
- A lack of thermal insulation, e.g., subcutaneous fat and fine body hair (especially in prematurely born children)
- The inability to move away from cold areas, air currents or heat-draining materials
- The inability to use additional ways of keeping warm (e.g., drying their skin, putting on clothing, moving into warmer areas, or performing physical exercise)
- The nervous system is not fully developed and does not respond quickly and/or properly to cold (e.g., by contracting blood vessels in and just below the skin). (Note that contracting these blood vessels has disadvantages, such as reducing immunity in the skin which could allow a skin or internal infection to develop, and perhaps reducing the rate at which the skin can heal.)
Brown fat in babies is known to be concentrated in the neck, upper shoulders, and upper back. How about adults? It was originally thought that brown fat all but disappeared in adults as they are more easily able to adapt and can shiver to provide body heat. Recent studies have shown that brown fat does exist in adults, but since adults have a better ability to regulate body heat, brown fat is much less prevalent and it “hides” in the absence of cold exposure.
Things should start sounding familiar at this point. The exact location of brown fat can be pinpointed by injecting a tracer and conducting PET scans typically after some sort of cold exposure. Below is a rendering of where brown fat is located in the body.
Surprise! Brown fat is still located in the same areas as infants; neck, upper shoulders, and upper back. Specifically on the posterior of the neck, above the shoulder blades, and in pockets down the spinal cord through the middle back. Things should start sounding familiar to what Tim Ferriss was promoting in his book, although it looks like he missed a couple spots.
Drug companies are starting to catch on to the benefits of brown fat in adults and are starting to work on pharmaceuticals that will increase brown fat concentrations. Any of these developments are probably in a very pre-trial form and will likely have some nasty side effects. I personally wouldn’t trust a drug company cocktail even if it existed now given their track record and incentives.
As I’ve noted above, there are plenty of natural ways that will stimulate brown fat using some sort of cold therapy. I’ve experimented with the method described in 4HB which basically said to get an ice pack and place it on your neck and upper shoulders while laying down.
I did this for a while but it is extremely inconvenient. After sitting at my desk at work for 9 hours the last thing I want to do is lay down. I need to move, but still do my daily cold therapy. So I started using an UnderArmour compression shirt that would hold the ice pack in place while I could stand up and move around freely. This was better but was suboptimal as I’ve found out because I was still missing cold exposure to several brown fat pockets, particularly in the middle to lower back and above the shoulder blades. This led me to hack together a prototype sleeveless compression shirt that placed ice packs strategically throughout the neck, shoulders, and upper back to provide maximum stimuli to brown fat pockets.
What I like about this shirt is that I can move around freely while still getting cold exposure. Additionally I can just throw the entire shirt in the freezer when I’m done with it. If I had two I could just switch shirts quickly and easily. I’m talking with a textile/fashion designer to bring this into production if there is demand for something like this. If you have any interest please comment below on your experiences and suggestions.
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