One of the key people studying the effects of cold exposure is the former NASA scientist Ray Cronise. Ray struggled with losing weight for quite some time when he came across an interesting discovery. During the 2008 Olympics it was a widely circulated claim that the swimmer Michael Phelps was consuming 12,000 calories a day. The average daily calorie intake of a regular U.S. citizen was 3,770 in 2014 (which is by the way the highest in the world). According to WebMD.com women should consume about 2,000 calories, while men should have no more than 2,400 calories a day. So how is it possible that Phelps ate almost four times as much as the average U.S. citizen and not gain weight? Just as a reference point it’s interesting to note that running an entire marathon burns “only” about 2,500 calories.
Cronise had a deep understanding of the physics behind heat transfer – otherwise known as the rules of thermodynamics – since he was employed to keep astronauts alive in space under extreme temperatures. It didn’t take much to figure it out: Phelps must be burning those extra calories simply by being in the 25-degree (77 Fahrenheit) water several hours a day. Amazed by his new discovery Cronise began experimenting with cold showers, ice baths and walking shirtless in winter, through which he ended up losing 12 kilograms (26.7 pounds) in six weeks. He measured his metabolic rate during and after cold exposure and found that his body was burning an enormous amount of calories. Rather than storing energy as fat his body was using it to keep his internal organs and core temperature on an adequate level.
Although Cronise states “you can’t freeze yourself thin”, combined with proper eating habits and some exercise temperature can have an amazing effect in developing one’s fitness. (Watch Ray’s TED Talk here!)
But weight loss is not the only benefit of experiencing cold on a regular basis. Wim Hof, the famous Dutch daredevil is known for his ability to withstand extreme temperatures for extended periods of time, which earned him the nickname “The Iceman”. Hof currently holds 21 Guinness World Records, including climbing to 7,300 meters (24,000 feet) on Mount Everest in nothing but shorts and a pair of boots, running a full marathon above the Arctic circle wearing again only a pair of shorts (no shoes this time) and climbing Mount Kilimanjaro in the exact same outfit (or rather lack thereof). He also holds the world record of being immersed in ice for 1 hour 52 minutes, doing that without dropping his core body temperature below the critical limit.
Another interesting outcome of Hof’s technique (now taught to people around the world as the “Wim Hof Method”) is that through his years of mindfulness, breathing and yoga exercises accompanied by extreme cold exposures on a daily basis he developed a way to influence his autonomous nervous system, something previously considered impossible by the medical community. Hof proved in a laboratory setting, that not only he is able to achieve such feats, but through his teachings his students, too.
In March 2013 twenty-four subjects at the Dutch Radboud University were injected with a dead strain of Escherichia Coli bacteria, which normally induces violent sickness with flu-like symptoms, such as high fever, headaches, muscle pain. Twelve of the participants were trained by Wim Hof himself, while the other twelve (poor guys!) were the control group with no preparation whatsoever. Amazingly enough, Wim’s students could suppress their immune responses to the bacteria and produced significantly fewer symptoms than the control group, who suffered from what was normally expected from such an infection. (Learn more about the experiment through this Nature article or this short Youtube video!)
So let’s look at how many ways can cold exposure benefit you based on the current standings in scientific research.
1. Increases alertness
Taking cold showers in the morning is a great way to kick-start the day! The deep-breathing response of the body to cold water (or some hyperventilation for the untrained) help us increase our oxygen intake as well as speed up our heart rate, thereby releasing a rush of oxygen-filled blood throughout our entire body. When you’re exposed to cold your body also increases the production of norepinephrine, which is a neurotransmitter involved in focus and attention.
The actress Katherine Hepburn was a big fan of cold immersion; she started taking ice-cold baths and cold showers at a very young age and persisted with this habit throughout her entire life. She died at 96.
2. Lowers levels of stress and depression
Cold showers and ice-baths have been proven to relieve stress and depression symptoms due to the intense impact on cold receptors of the skin, which send a tremendous amount of electrical impulses from the nerve endings to the brain. It produces a natural antidepressive effect and you experience an immediate mood boost. There is also an increase in gluthathione, an antioxidant that keeps other antioxidants in the body performing at optimal levels, dampening the detrimental effects of oxidative stress on mental health.
3. Stimulates weight loss
As we have seen in the case of Ray Cronise, cold exposure can effectively aid weight loss. When studying the eating habits of Michael Phelps, Cronise discovered that keeping your body warm in cold temperatures requires an enormous amount of energy, thereby calories burn a lot faster, so eventually there is less remaining for your body to store as fat.
Speaking of fat the human body actually contains two types of distinctive fat tissues, the so-called white fat and brown fat. White fat is what most of us are familiar with; it is the one that our body accumulates when we consume more calories than our body needs. It puts them in a reserve known as body fat, which usually piles up at our waists, thighs, neck and lower back and that we’re so desperately trying to eliminate.
Brown fat on the other hand is the “good fat”. It’s a lot less visible, and it’s designed to help our body generate heat to keep itself warm when exposed to cold temperatures. It gets activated by cold exposure, and the more we expose ourselves to such conditions the more brown fat tissue is generated (or gets converted from white fat). This is the type of fat our ancestors used to have and that most of us are lacking today do to the luxury and comfort we live in. (Read more about brown fat in this Live Science article!)
4. Speeds up recovery
Ice baths among top athletes have become a common post-workout practice in the past years as more and more studies point out the effectiveness of cold on muscle soreness. In 2009 The New England Journal of Medicine conducted a study on 360 people, who either rested or immersed themselves in cold water after extensive resistance training, cycling or running. They concluded, that subjects exposed to cold water experienced a faster recovery from muscle soreness in the one to four day post-workout period, than their relaxing peers.
There is one important note though when talking about post-training cold exposure. When you’re doing strengthening exercises – without going into the details – you generate chemicals in your body that help you increase muscle mass. When exposing yourself to cold immediately after exercising you suppress this beneficial process, so if the goal is to build muscle, avoid the cold in the first hour after strength training! (On the other hand, spending some time in the sauna after workout does just the opposite; it actually helps you in building muscle mass.)
5. Improves circulation
When cold water hits the body its natural response is to shut down the circulation beneath the skin and at the extremities (hands and feet) to focus the energy on protecting the inner organs that are critical for survival. When you stop exposing yourself to the cold, the circulation in the aforementioned areas starts up again, making your heart pump fresh new blood to the areas that cooled down in the process. It’s like restarting your computer – it always runs smoother and faster after all the junk is cleared from its memory.
Additionally, this process can also lower your blood pressure, clear blocked arteries and result in an improved immune system overall.
6. Improves the health of your hair and skin
Cold showers are clearly the most natural way of improving your appearance when it comes to hair and skin. As opposed to hot water, cold doesn’t dry out your skin, it leaves all the healthy natural oils on it, while sealing the pores and tightening its surface. Regular cold showers will also lead to shinier, stronger and healthier hair and an increased ability for it to grip the scalp.
You don’t have to worry that cold will make your hair fall out, it’s a myth (here is a message to your mom). In fact, it’s quite the opposite. The so common dandruff is also not caused by cold air or water, it’s rather an overabundance of malassezia fungus, which causes the build-up of dead skin cells on the scalp. It can be attributed to several factors including stress, vitamin deficiency or improper cosmetic products, but it can also be caused by the frequent combination of overheated rooms in winter and the cool dry air outside.
So how cold is cold enough to achieve the aforementioned results? In case of showers simply turn it all the way down and enjoy what you get from the water system. Staying under the shower for 3-5 minutes per session is adequate to experience most beneficial effects. In case of cold baths most rehabilitation specialists recommend starting with 10-14 degrees (50-58 Fahrenheit) and 6-8 minute sessions. Once you get accustomed to the cold and developed a certain amount of brown fat you can experiment with cooler temperatures, but don’t exceed the above timeframe.
As a final note it’s important to state that despite the fact that exposing our bodies to extreme cold temperatures can feel unpleasant, especially in the beginning, it’s generally safe for people without any heart related medical conditions. As always, listen to your body; individual tolerance limits can vary widely, and pushing yourself too far can result in undesired consequences.
With that being said, feel free to practice, experiment, and witness the amazing results of cold firsthand!