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Could something as simple as a regular 5-minute cold shower be an effective tool for fat loss? Sounds too good to be true – but you might be surprised to learn that there is a surprising amount of good research to suggest this just might be the case.

Cold Water Immersion

Ray Cronise, a former NASA scientist is one of the most high profile proponents of cold therapy for fat loss. As a former physicist, Ray Cronise used his knowledge of physics and the associated laws of thermodynamics to spark a new approach to weight loss. Ray’s crusade into this area was triggered when he learned about the typical daily calorie intake of record gold medal-winning Olympic swimmer Michael Phelps. During the peak of his training, Phelps was reported as saying he consumes around 12,000 calories a day. Even accounting for the 4-6 hours of training a day that Phelps would have been doing, there is no way he would be expending enough calories to cancel out his huge calorie intake. The unique thing however about Michael Phelps when compared to another world class endurance athlete like Cadel Evans is that Phelps spends most of his training time in water as opposed to dry land. Why is this significant? In short it has to do with thermal conductivity of water versus air and newly discovered mechanism by which the body can regulate its temperature. Water is over 20 times more thermally conductive than air - meaning it conducts heat away from the body much more effeciently than air. So the body has to work alot harder to maintain its temperature when in water as opposed to air.

Core Body Temperature Regulation in the Human Body

To maintain proper function, the body must keep its core temperature within a narrow range of between 36oC and 38oC. So when subjected to cold environments, the body has to generate extra heat. One of the mechanisms it does this is by altering the flow of blood to extremities and the associated web of capillaries under the surface of the skin. However, the other key mechanism is via activation of brown fat1. Previously thought only to be present in infants, landmark studies in 2009 revealed that humans had varying amounts of brown fat, and whats more, activation of brown fat is correlated with lower adiposity2-4. The unique thing about brown fat is that it has the ability to generate heat independent of ATP production5. This has put the humble brown fat centre and front of much of the research focusing on new therapeutic approaches for obesity.

Muscle Can Turn Up The Heat Too

While activation of brown fat is a key mechanism that mediates the body’s adaptive response to cold exposure, researchers have also discovered that muscle tissue has the capacity for what scientists term “cold induced adaptive thermogenesis”. Similar to brown fat, this adaptive thermogenesis in muscle occurs via a process called 'mitochondrial uncoupling'. This term describes the phenomena whereby energy produced in mitochondria is dissipated as heat rather than coupled to ATP production. In simple terms its a mechanism the body has to generate heat while burning calories. Studies have shown that mitochondrial uncoupling in muscle can contribute as much as 20%-50% of the resting metabolic rate6, 7. So muscle tissue is definitely another major site of regulation of energy expenditure during cold water therapy.

Cold Water Therapy Confounds Traditional Wieght Loss Models

Expending calories in order to heat the body would be one possible explanation by which a swimmer like Michael Phelps could maintain such a disproportionally high calorie intake and not put on weight. This scenario also helps explain why the much touted weight loss notion of balancing calories 'in' with calories 'out' is too reductionist and simplistic. The question for Ray Cronise then became, what are the best strategies in terms of cold therapy to activate an individual’s brown fat regularly and reliably.

What many weight loss schemes neglect to recognise are the additional calories that are consumed as part of normal metabolism. Some examples include; calories used in involuntary movement; calories used with inflammatory and infectious processes; calories used in growth and tissue restoration/remodelling; calories not absorbed in the digestive tract and much more. However, unlike many of the preceding factors, the calories used for heat generation and in response to external temperatures is something that is largely controlable.

The question then becomes what is the most practical and effective way of altering cold exposure so as to bring about consistent changes in the body’s activation of its brown fat stores. Enter cold showers and ice baths.

Examples of Cold Water Therapy

There are a variety of ways to do cold water therapy. The most extreme form is called cryotherapy where individuals are housed within specially constructed cold chambers that range from -120oC to -140oC. Such chambers are widely inaccessible and the therapy itself is expensive, making it an impractical option for most. The other option is cold or ice baths, while the most popular option is cold showers.

Ice Baths

Ice baths simply involve a subject sitting in a bath which has ice cubes added to it. The most popular option is sitting in waist high water for up to 20 minutes. This is one of the more cumbersome methods of cold therapy as it requires that subjects either prepare or purchase ice cubes. The most extreme form of ice bath is where subjects immerse themselves in a chamber filled with ice. Wim Hof (pictured right) is the most well known proponent of this extreme form of cold therapy. Getting to this level of cold tolerance, however, requires extreme dedication and is not realistic for the average individual.

Ice Packs

Because most of the body’s brown fat is stored in the neck and upper chest/shoulder regions, one of the basic forms of cold therapy is to place ice packs on the upper chest and upper back (supraclavicular region) for 20-30 minutes per day. For arguments sake, this could be done whilst watching TV or sitting down at the dinner table.

Cold Showers

The most common and popular form of cold water therapy is cold showers. Presumably because it is the most practical way of doing cold water therapy. It also happens to be the preferred therapy that Mr Cold (aka Ray Cronise) himself recommends. However, Ray has a particular variation on your standard cold shower, which involves the use of alternating burst of hot and cold water. The particular technique involves a cycle of 10 seconds warm water followed by 20 seconds hot water. This cycle is repeated preferably 10 times, after which subjects ideally finish with a 2-3 minute stream of cold water.

Some individuals may find going straight into a cold shower too uncomfortable, in which case they can start by turning the hot tap off at the end of their shower and slowly submerging their feet and lower limbs into the cold water; progressing slowly over the subsequent days until they are comfortable to submerse their whole body under the cold water.

Cold Water Therapy Into The Future

With the rates of obesity now at epidemic proportions, its likely that research into the effects of cold water therapy on fat loss will continue at a rapid pace. Future studies will likely explore the most effective protocols for eliciting maximal rates of fat loss in a range of individuals. The greatest appeal of this type of obesity treatment is that it is virtually cost free and can be implemented by anyone. In many ways it represents a potential magic bullet for weight loss. It will be exciting to see the developments in 5-10 years time.


1. Yoo HS, et al. Intermittent Cold Exposure Enhances Fat Accumulation in Mice. PLoS ONE. 2014;9(5): e96432.
2. Cypess AM, et al. Identification and importance of brown adipose tissue in adult humans. N Engl J Med. 2009;360:1509–1517.
3. Saito M, et al. High incidence of metabolically active brown adipose tissue in healthy adult humans. Diabetes. 2009;58(7):1526-31.
4.Virtanen KA, et al. Functional brown adipose tissue in healthy adults. N Engl J Med. 2009;360: 1518–1525.
5. Ouellet V, et al. Brown adipose tissue oxidative metabolism contributes to energy expenditure during acute cold exposure in humans. J Clin Invest. 2012;122:545–552.
6. van den Berg SA. Skeletal muscle mitochondrial uncoupling, adaptive thermogenesis and energy expenditure. Curr Opin Clin Nutr Metab Care. 2011;14(3):243-249.
7. Wijers SLJ, et al. Human skeletal muscle mitochondrial uncoupling is associated with cold induced adaptive thermogenesis. PLoS ONE. 2008;3(3):e1777.

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