How many times have you been nagged with the comment 'you'll catch a cold outside, put a jacket on'. Well, what if I told you that's not necessarily true... what if it was the exact opposite and actually being cold and shivering is good for you? I'm sure you've heard friends and family members talking about their newfound love for Wim Hof or maybe stumbling upon extravagant others on social media submerging themselves into an ice lake in the depths of winter. There is method to the madness I promise... chances are they are participating in cold thermogenesis to reap the physiological and metabolic benefits.
So, what is cold thermogenesis and what are the benefits?
Firstly, let's take a look at what thermogenesis is...In simple, thermogenesis means the generation of heat. It plays a significant role in regulating your body's temperature as well as directly affecting your metabolism through eating, breathing and exercising.
Our body functions optimally at a temperature of about 37°C and with a slight increase or decrease from as little as 5 degrees, our body goes out of whack. In response to this change, our Hypothalamus is straight to the rescue. Located in the centre of the brain, the Hypothalamus is responsible for thermoregulation, or in other words maintaining and balancing our ideal body temperature. When you are cold your body shivers, causing your muscles to contract repeatedly. This generates heat and increases your metabolic rate. In fact, shivering for 15 minutes can burn roughly around 100 calories. The muscles respond by secreting a hormone called Irisin that stimulates heat production. Irisin is a thermogenic protein that promotes energy expenditure by white adipose tissue (WAT) browning. In other words, turning white fat into brown fat.
What does this mean?
You have two types of fat in your body. The first is white fat which we are familiar with, it sits around your hips, waist and belly waiting to be utilised for energy. It stores the most amount of energy in large fat droplets that accumulate all around the body. However, in humans, too much white fat is bad and can lead to obesity. The second, and more preferable is brown fat or brown adipose tissue (BAT) which stores energy in much smaller quantities. It is predominantly filled with iron-rich mitochondria and when this type of fat burns calories, it creates heat without shivering, also known as cold thermogenesis. When BAT is triggered it directly mobilises the energy stored in white fat to generate heat. Studies show that people who have higher levels of brown fat typically have lower body weight and significantly reduce their risk of developing diabetes and obesity.
Originally, scientists believed that only babies had this type of brown fat and it diminished by the time you arrived at adulthood. Research now suggests that adults actually hold small reserves of this brown fat. It is found predominantly around the shoulders, neck and spinal cord. You can further recruit BAT under the right circumstances, enabling you to actually convert white fat into brown fat through exercising and exposing yourself to cold temperatures. Which brings us nicely to cold thermogenesis.
Cold Thermogenesis involves regularly exposing your body in either a cold shower or bath, splashing cold water on your face, wearing body cooling gear or if you’re going all out… a cryotherapy chamber. In order to activate the thermogenic response, you can use Ray Cronise’s Shiver system which is a 5 minute cold shower at the beginning or end of your day, alternating 20 seconds of freezing water to 10 seconds warm water. Repeat this for a total of 10 times. If you are feeling a little more hardcore and fancy submerging yourself into a freezing lake or pool, make sure you build yourself up to this point over time.
Now that we understand that cold thermogenesis occurs when your body is below its optimum temperature, it can be summarised that this cold exposure stimulates brown fat to burn white fat, ultimately burning more calories. However, this is not the only health benefit. During prolonged cold exposure there is an increase of the hormone adiponectin, its main function is to assist fat burning but it also sends the blood glucose stored within fat into the muscles, optimising and reducing time recovery from exercise. Cold exposure can also reduce inflammation post resistance training, you may already be an advocate for ice baths or cold showers to help elicit muscle soreness or DOMS. This method for recovery will not only reduce swelling but it increases circulation of blood to the muscles. Switching from hot to cold improves lymphatic flow. The lymphatic system is responsible for carrying waste products from immune-related activity. Causing your body to repeatedly contract when shivering assists metabolic waste products out of your body.
Additionally, cold thermogenesis can improve your sleep. Most of us have unfortunately experienced a restless night when you were too hot in your bed. Your body has an optimal sleep temperature of around 16-18°C but sometimes, depending on your day you may struggle to cool down effectively before bedtime. A cold shower before bed can help reset your body temperature, beginning the cool-down phase. This triggers the release of melatonin, the hormone that regulates sleep, sending your body into its natural sleep cascade.
Finally, is the effect it can have on your immune system. Immersing yourself into a cold environment puts slight stress on your body that shocks your body into a fight or flight response and forces you to breathe differently. Studies have shown that a cold shower can activate and elevate levels of two important virus-fighting cytokines.
If you feel like this is something you would like to incorporate into your daily routine to reap the metabolic and physiological benefits then my top tip would be not to overdo it. Start small and build yourself up to it! It is also important to understand that this is not simply a singular method for fat loss. This does not outweigh the benefits of consuming a whole food nutrient-dense diet alongside maintaining an active lifestyle.
Thanks for reading, until next time!
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Li, H., Zhang, Y., Wang, F., Donelan, W., Zona, M.C., Li, S., Reeves, W., Ding, Y., Tang, D. and Yang, L., 2019. Effects of irisin on the differentiation and browning of human visceral white adipocytes. American journal of translational research, 11(12), p.7410.
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