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Cold Water Immersion: The Unexpected Science

Apr 04, 2019

"Cold water immersion"?

What's that?


Cold tub therapy.

Or sitting inside an ice bath...

You may think: "are you freakin' insane?"

Not at all...

This 12,000-word guide looks at which claims in relation to cold water immersion are science-backed--and which are not.

For years gurus have been saying that cold water immersion melts fat quicker than ice cream laying in the sun, become superhuman after skinny dipping in ice three times, and promises that you'll sleep like a baby at night.

And you know what?

There's truth to these statements. 

Some truth. 

Scientifically validated benefits of cold tub therapy do include increased fat loss, deeper sleep (in all likelihood), well-being improvements, and pain reduction.

Throw in increased workout performance, better circulation, more control of hunger, and slower aging on top of that, and you think you've found the fountain of eternal youth and health.

And yet, these benefits don't come simply...


Well, many health strategies are simple, and yet, most people are not consistently using them. 


Sleeping at the right times at night is very simple, and has massive health benefits, just as healthy eating does, and yet, most people don't routinely take these actions.

In fact, many people eat unhealthily and stay up late while ruining their sleep, even though they know better.

Cold therapy is similar.

Sitting for 15 minutes in a cold tub, or taking an ice bath for 3 minutes is not much fun (for most people).

Safety is also a possible issue: you can damage your skin, and get hypothermia or frostnip on your hands and feet...

For that reason I'll mainly describe the effects of superficial cold therapy in this blog post

Using superficial cold therapy you won't cool your body so much that any health dangers emerge. You'll end up with cold therapy that's challenging enough to improve your health, but never puts you at risk.

Before taking any cold baths, I also highly recommend building up your tolerance with cold showers first. 

And if you do use cold baths, use a skin infrared thermometer and don't let your skin temperature fall under 10 degrees Celsius (55F). Additionally, buy neoprene gloves and socks to protect your hands and feet.

Don't make your sessions too long either. And if you've got a medical condition, always consult with your physician first before applying cold therapy.

In this full blog post I'll give you many different methods to use cold water immersion, such as visiting a lake, putting a tub or barrel in your yard, or installing the ultimate $10,000+ Cold Tub in your bathroom (which automatically cleans itself and keeps a 5 degrees Celsius temperature all year round...

This small summary does no justice to the depth and complexity of this blog post, so keep reading.

The possibilities are endless--and possible health benefits too.

Fasten your seat belt, and let's begin:

a woman who is taking a cold plunge in a lake

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cover photo for this blog post, which shows a woman who is using cold water immersion in the ocean

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Author: Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS).



Cold Bath Therapy Basics:

1. Introduction - Cold Water Immersion: Ferocious, Yet Amazing
2. How Cold Therapy Works: Brown And Beige Fat Creation And Activation

Cold Water Immersion Effects:

3. Ten Ice Bath And Cold Water Therapy Benefits
4. Seven (Possible) Cold Bath And Ice Bath Side-Effects

The Big Picture: Implementing Cold Therapy Into Your Life

5. Get Your Own Cold Tub, Cold Plunge Pool, Or Cold Water Immersion Tank + Cold Therapy Dosing
6. Conclusion: Time Will Tell Whether Cold Bath Benefits Are Overstated Or Underestimated


Return To Table Of Contents



"Cold water immersion" is truly simple: find a lake or fill a bath tub with cold water, and sit inside that water for some time. 

Many different names exist to describe that same phenomenon: "cold water immersion", "cold water therapy", "ice baths", "cyrotherapy" (translation: ice therapy), "cold tub therapy", etcetera

I'll use these terms interchangeably in this blog post.

And for many people, one picture is worth a thousand words, so in that case:

Bart Wolbers who is using an ice bath

Yes, that's me during Dutch the wintertime. I've actually placed a 400+ gallon tub in the garden to carry out my cold water therapy sessions. 

Many health effects have been attributed to cold exposure, such as increased energy levels, fat loss, well-being, dopamine levels (a signalling substance in the brain that makes you motivated), muscularity, sleep quality, and more.

And due to the presupposed benefits of cold, athletes use cold to boost their recovery, for example.[1; 2] Unfortunately the effects of using cold directly after exercise have been underwhelming.

Many people also use cold therapy to increase their fat loss, boosting their mood, and for many other benefits. 

In this blog post, I'll scrutinize these claims through science one-by-one.

I've been acquainted with cold water immersion for a couple of years now - the topic has fascinated me.

In college in 2016, for example, I actually wrote a systematic review on the topic but I never pursued publication. 

After writing the systematic review, I bought the tub that's displayed above. I "practiced" cold for years. And before that time, I had already used cold showers regularly.

I also walked outside without a jacket for two years, even during freezing temperatures.

Cold exposure has become a extremely popular health technique in the last few years.

Cryosaunas are also popping up everywhere, for example. Cyrosaunas use nitrogen vapor at a really low temperature of -128 degrees Celsius (-200F), to cool the body down dramatically in a few minutes.[3] 

Contrast therapy is yet another possibility, in which you alternate between cold and hot water.[4] Cold showers are also all the rage.

In this blog post, I'll mainly focus on cold water immersion, i.e., using a tub or bath to with cold water.

I've personally gotten lots of benefits from cold tub therapy, but I also know the therapy is not for everyone


Most of the studies I list in this blog post investigate the effects of cold tub therapy which is a synonym for cold water immersion.

For clarifying general physiological effects, however, I've also includes studied with other types of cold exposure too such as cold air.

Caveat: because many different studies use diverging protocols for investigating cold, the outcomes may be harder to generalize. I have, however, made sure to make the picture as complete as possible.

Another caveat is that most studies are carried out on young Caucasian males. If you're a woman, older, or if your ancestors come from another geographical region you may respond differently to cold - a topic I'll cover later.

The bright side is that you can test how you react to cold. One experiment entails simply watching how you feel in daily life after integrating cold. Are you more energetic and sleeping better? In that case, cold is doing its thing for you.

Ready to go?

Let's then move on to the second section, where you'll learn about through which mechanisms cold affects your physiology.

Nature Builds Health's Health Foundation online Program 


Return To Table Of Contents


Let's start stupid simple:

The longer you stay in cold water, the lower your body temperature becomes.[33] And the more often you expose yourself to cold, the greater your ability to withstand it also gets (as long as you're not overdoing the stimulus).[48] 


Well, your body contains different types of fat - or "adipose tissue" - which are categorized according to their color. Three colors exist: white, beige, and brown. 

The white adipose tissue is more inert, mainly supplying energy to your body.[49; 50]

White fat does have some functions as well, such as secreting a hormone called "leptin" which signifies your body's energy status.

For many years the existence of brown body fat was questioned, until several publications in 2009 (re-)affirmed that heat-producing body fat in humans.[191; 192] Studies in the 1980s had already posited the existence of that fat, but not much thought was given to the topic back then.

Beige and brown fat are metabolically active, contrary to white fat (or white adipose tissue) - meaning that they can actually use energy to heat your body up.

In other words, glucose and fat in your body can be burned off by brown fat to generate heat.[56-58] All mammals have that ability in one way or another.[58; 59] 

By creating heat, you're able to survive in colder environments. While staying warm doesn't seem special, the dinosaurs actually went extinct because they could not keep their bodies warm without the sun, after post-meteor strike pollution massively cooled down the earth...

an ice bear with lots of fat, to demonstrate how a bigger body insulates you from the cold
Polar bears: kings of staying warm in the cold, in part,
by using body fat insulation very efficiently.


The more frequently you activate your brown adipose tissue (BAT), the greater both it's availability and activation become in your body.[112] In other words, after exposing yourself to cold long enough you'll end up with more brown fat, and existing brown fat will be used more efficiently. 

Most of that brown body fat is located around your neck, chest, and inside your belly.[105]

Some deeper muscles around the spine and pelvis (hips) may also be activated to generate heat during cold.[97]

Also, recall that during times you've been really cold that you were probably shivering.[52] That shivering mechanisms works through your muscles as opposed to fat - heat is generated due to the fast contraction of your muscles.

Brown fat generates heat without you having to shiver. 

And guess what?

The better your adaptation to the cold, the less you'll actually need to shiver, and the more you'll rely on brown adipose tissue to generate heat.[190]

The older you get, the less brown fat present in your body. Females generally also have higher BAT levels, which may be explained through higher levels of a hormone called "estrogen".[125; 126]

You need to heat your body up because without staying warm you cannot survive. 

You may already know from reading my blog post on basal metabolic rate that the body expends most of its energy on basic processes such as keeping your body at a stable temperature. In fact, up to 40% of energy is used for that purpose.[103] Most oxygen you consume is used for the same goal.[104]

But exactly how does brown fat cells generate heat? Simple: they contain mitochondria.

Up to 90% of the energy in cells is created by mitochondria. Mitochondria are often known as the "energy producing factories" of the cell.

Mitochondria in brown fat cells contain a protein called "uncoupling protein 1".[60; 61] Different uncoupling proteins exist, but most of these are not as well studied as uncoupling protein 1.[106]

When uncoupling protein 1 is expressed to a great extent in mitochondria, less ATP is formed (the traditional form of energy used throughout the body), and of the input of mitochondria (such as food) is burned off as heat.

And while you need ATP for movement or brain function, for example, using most of your food towards energy for movement won't save you during a cold winter. Only sufficient heat helped you survive a Canadian or Norther European winter in the past...

Animal studies demonstrate that brown and white fat are even structurally composed of different types of fatty acids.[98] With cold exposure, that brown adipose tissue's fatty acid type is remodeled to help it cope better with future demands.

To be sure: exercise and cold exposure are not the same thing either.

Exercise decreases the activation of brown adipose tissue. That result almost certainly occurs because increased heat generation is counterproductive when you're already heating up through exertion.

The benefits of exercise and cold don't overlap either. But exercise and cold therapy are similar in that both result in the creation of stress hormones to meet energy demands.[67]

(Nerd section: with uncoupling, protons leak across the inner mitochondrial membrane, bypassing the last ATP synthase step in the mitochondria. Other biochemical pathways may contribute to heat generation as well.[107;108] The validity of ATP being the main source of bodily energy has been questioned. 

Different interpretations also exist of how exercise and cold affect brown adipose tissue activation.[71-74] In animal studies, exercise paradoxically decreases fatty acid uptake in brown fat, but that conclusion may be confounded by exercise-induced heat generation.[91; 92]

A brain area called the "hypothalamus" is responsible for the creation of stress hormones that help you cope with the cold.

You can view that hypothalamus below:

a human brain, with an emphasis on the hypothalamus which has a role in temperature regulation



After cold exposure, the hypothalamus signals through intermediaries to your adrenal glands that stress hormones such as cortisol and adrenaline need to be created. That process helps your body mobilize energy. 

Finally, uncoupling protein 1 is activated, boosting heat production in the mitochondria. 

(In reality, the mechanism by which the human body adapts to cold is more complex than I'm letting on here.[161])

Notice that I'm calling cold exposure "stress".

Please keep in mind that I do not consider stress necessarily bad, as long as your body can adapt to that stress to become stronger and healthier than before. Not all stress is created equal, as some types of stress are even detrimental to your health.

Exposing yourself to lots of radiation or noise are an example of useless stressors, because your body will never get stronger when exposed to them--they only bring health losses. I do consider cold exposure a stressor that can have health benefits. 

For further reading on my conception of stress, read my 100% free epic guide on the topic.

And you know what?

Cold exposure is nothing new--it's been part of the human condition for millions of years.

Several ice ages occurred during the past millions of years in which hominins lived and evolved.[138; 139] Hominins are the category of human(-like) ancestors, not to be confused with primates, which culminates in the human species you're part of: homo sapiens.

The last Ice Age lasted from 2.6 million years until 11,000 years ago, with warmer and colder periods existing during these times. And while different classifications of cold and warmer periods prevail, the scientific consensus upholds that many periods were colder than the world you're living in today.[140]


Huge glaciers covered many parts of the earth during the last Ice Age, with Northern parts of Europe, North America, and Asia being uninhabitable.

To survive that cold your body had to generate heat. Your (indirect) Neanderthal ancestors, for example, had excellent potential to adapt to cold, which is probably why Neanderthals populated Europe before your species Homo sapiens did.[169] 

Neanderthals carry both more muscle and fat than humans do, thereby achieving greater insulation. It's also likely that Neanderthals carried more hair than humans.

a neanderthal visualized, to show their better capacity for insulation than humans do
Neanderthals - even notice their huge skeletal structure compared to modern humans.


Neanderthals have been extinct for approximately 40,000 years, when the Earth became warmer again, and insulation and hair no longer was an advantage. Homo sapiens may have even contributed to the demise of Neanderthals.

Now, the human ability to resist cold exposure has been lost throughout the last decades. Modern buildings are continually kept at 21 degrees Celsius (~70F), preventing your body from ever overheating or being cool.

Intermittent overheating and cooling can be very important for your health though, and most modern humans no longer profit from these benefits. If you're curious: I've treated the topic of overheating in great detail in my blog post about infrared sauna benefits. This blog post considers becoming under-heated (or cooling down).

Both overheating and under-heating can thus threaten survival.

With the previous ice ages, maintaining temperature was central to human survival for millions of years. Agriculture with permanent housing 10,000 years ago probably already started that trend of humans creating more stable temperatures in their environments.

Different mechanisms to lose heat and increase (and thus manage) bodily temperatures exist.

Sweating is the mechanisms by which you're losing heat.[145-147]

The more frequently you're sweating, the higher your ability to withstand heat becomes.[148; 149] Sweating more also leads to greater the water and salt (sodium) losses. 

If you were born in the tropics, you generally have a better ability to sweat than if you were born far away from the equator - black skin literally has more sweat glands.[160]

Two mechanisms exist for heating up your body: "non-shivering" and "shivering" thermogenesis.[143; 144] 

Both forms of heat generation result in glucose and fatty acid depletion.[151-153] Brown adipose tissue is especially important for activating non-shivering thermogenesis.[166]

Shivering thermogenesis is only activated once non-shivering thermogenesis no longer suffices for increasing bodily temperature.[150] That need to shiver thus entails that you're pushing the limits of your heat-generation capacity. 

Fortunately, the shivering variant of thermogenesis has far greater potential to create heat than its non-shivering counterpart.  Your muscles can increase your metabolic rate by up to 20% through shivering, for example.[203]

In colder temperatures, humans even subconsciously tries to minimize heat loss. Babies, for example, already alter their posture in colder environments to save energy.

Just as the case with withstanding heat, individual differences between how you're able to deal with cold exist as well.[157] Both your regular DNA, found in the center or "nucleus" of the cell, and the DNA of your mitochondria, both affect how well uncoupling proteins work in your body.[158; 159]

Yes, that's right: your body contains two types of DNA.

Due to that DNA variation, different people respond to cold in different ways, and also have different adaptive capacities to cold.[162] Asians living in Europe, for example, do not have the capacity to generate heat through brown body fat as Caucasians living in that same place.[167]

(I don't feel bad for Asians though - Asians score better on IQ tests than Caucasians across the board, on average. I'd make that trade any day, as cognitive capacity is one of the main determinants of how you'll end in modern society--fat burning capacity through cold exposure is not.)

Your ability to cope with cold also alters seasonally - you'll generally have higher cold resistance levels during the wintertime.[163; 165]

Clothing was only used relatively late in human evolution, up to 100,000 to 200,000 years ago.[156] My timing is that humans discovered how to intentionally control fire 800,000 years ago, so that millions of years your ancestors used brown fat and shivering to generate heat.

mammoth bones. Mammoths did not survive the ice age
Mammoths went extinct before the ice age ended as well, in part due to human over-hunting. Mammoth meat was prized due to its higher fat content, and was thus perfect for helping you survive the cold.


So why should you care about becoming really hot and cold once in a while?

Well, living 24-7 in environments with very stable temperatures is associated with increased obesity risk.[141; 142] 

That finding is no coincidence:

Carrying increasing quantities of brown fat on your body makes you less prone to be obese.

Obesity puts you at risk for many different disease, especially when you're younger, such as diabetes, heart disease, and cancer.[53; 54] You'll also age quicker if you're obese at younger, although carrying some extra body fat may be protective in older age.

Many different health benefits of brown fat activation exists, such as:[62-66]

  • improving insulin sensitivity, which is your cell's ability to take up and use carbohydrates;
  • lowering triglyceride levels, a marker in the blood that's associated with heart disease. Triglyceride levels shouldn't be too high
  • naturally lowering excessive cholesterol levels, while keeping your blood vessels and arteries healthy. Cholesterol, however, might be less well of a predictor than previously expected.[234]

In animal studies, a glucose transporter called "GLUT 4" is increasingly expressed with cold exposure, resulting in an improvement in glucose can be transport inside a cell (and thus lowering excessive blood sugar levels).[75-77]

In humans too, the end result is that glucose is taken up much better, even if you're obese.[78-81] Longer periods of slight cold exposure work perfectly, so turn down that thermostat!

Cold exposure, in fact, is an even greater stimulant to take up glucose in brown fat than insulin is.[82] Nevertheless, fatty acids - either taken from body fat or diet - are the main substrate traditionally used for energy creation in brown fat.[83-88]

Fatty acids are only used as a fuel source once carbohydrates (i.e. glucose) stores have been depleted from your muscles and liver. 

Upon exposure to cold, fatty acids are increasingly released into the bloodstream, serving as the energy substrate to increase body temperature.[84] 

A fascinating fact?


Brown fat always retains its ability to use fatty acids as energy, even though your body might not be able to properly use glucose due to diabetes.[89; 90] Of course, the same is true for muscles, that it's interesting to see the fail safe at different points in the human body.

The more frequently you use your brown adipose tissue, the more it grows in both size and activation potential.[110] 

Outdoor workers therefore have higher brown adipose tissue levels compared to indoor workers in general.[96]



If you work outside for a longer period of time, your body has to generate lots of heat. New mitochondria then need to be created to generate that heat in brown body fat so that you'll stay warm.

Overall, outdoor workers thus have many advantages over indoor workers, such as an increase in movement, sunlight exposure, and cold adaptation. 

Animal studies also demonstrates that thyroid hormones - which can be visualized as a thermostat of energy use - affects brown fat availability.[122; 123] A thyroid that's too slow or quick (I'm oversimplifying) can reduce brown adipose tissue availability - a topic I'll come back to later.

a picture of a lumberjack working outdoors
Why grandpa was always lean: sunlight, physical activity, and cold during the wintertime


Now, you may think: "you've only been talking about brown and white body fat. How about the beige variant you talked about earlier?"

Thought you'd never ask... 

Under certain circumstances, white adpose tissue can transform into beige or "brite" adipose tissue. Beige fat exhibits similarities in both humans and rodents.[109]

A lot of the brown fat that's located around the chest, back, and neck also contains some beige variant as well.[115; 116] That brown and beige fat is strategically located: blood frequently passes by those locations, so that the re-heated blood can warm the entire body once it circulates.

Beige fat is categorically different from brown fat though, as very different genes are expressed (activated) within the two types.[113; 114]

The difference between beige and brown fat is that beige fat has lower uncoupling protein 1 expression levels, unlike brown fat. Under cold exposure, however, white fat can increase its gene expression of uncoupling protein 1, so that more heat can be created.

A hormone called "irisin" helps turn white fat into the beige variant - surprise, surprise: cold exposure increases irisin levels.[230; 231] 

Overall, the creation of heat in your body is thus more complex than you'd initially thought - and probably turns out more complex in the coming decades. At least you now know that brown and beige fat deposits have all round health benefits.

That's it - all you need to know about brown and beige body fat, and its relationship to human evolution and temperature maintenance. 

I'll explore all known health benefits of cold exposure in the next section.

a brown bear who is laying in the water, which then activates his brown adipose tissue
"Never too late to convert white fat to beige fat, human!" 


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In this section I'll consider all the benefits of cold bath therapy.

Keep in mind that the benefits of cold exposure depend on you as an individual - benefits may be greater or lesser depending on your personal context.

So let's start with a benefit that can help almost everyone:



Whenever you affect the temperature of the skin, sleep quality is also affected.[214] Many people know that sleeping in a room that's either too hot or too cold reduces sleep quality.  

Even though many people experienced upgraded sleep quality after integrating cold water immersion into their lives, especially during hot summers, current publications do not directly demonstrate that the activity increases sleep quality (yet).[215]

The quality of studies investigating that phenomena is low, nonetheless, and a proof for the increase in sleep quality can reasonably be expected in the future. 


Well, perceived sleep quality after cold exposure does goes up, for example.[216] Heart rate variability, the interval between heart rates which is a measurement for recovery, can also be positively affected by cold exposure.[217]

And last but not least: greater quantities of brown adipose tissue are also associated with higher sleep quality as well.[226]

So while short-term studies may not be able to demonstrate an increase in sleep quality after a few cold tub therapy sessions, studies with a long-term perspective may show a connection because it takes time to build brown fat deposits.

a sleeping polar bear that is very tired
With the right cold exposure intensity, this is how you may be sleeping after a while.




Contradictory evidence currently exists in this area. Some studies show no difference between simply resting (passive recovery) and cold water therapy.[7; 8; 12; 29; 33] And when compared to active recovery (simple movement), cold water immersion may not be superior.[22]

Other studies do show cold water therapy being superior.[30-32] So why that discrepancy?

One explanation for these results is that cold baths lower inflammation, even though adaptations to damage that occurs during exercise requires inflammation.[13]

Let me give an analogy:

Taking antioxidants that completely removes the (oxidative) damage that occurs after exercise, for example, but has been shown to lower adaptations to exercise.[24] These free radicals are necessary to tell your body to adapt.

Lowered adaptation entails that you're not becoming stronger after a workout. 

Many of the studies investigating cold bath therapy make the error of using cold exposure immediately after exerciseThat's a mistake, just as using antioxidants immediately after exercise is.

Ice baths should thus always be planned far away from exercise sessions, and not immediately afterwards. I also recommend using cold water immersion on days you're not using exercise - that way it's impossible for cold to inhibit the adaptation process.

If you do use cold after exercise, lower water temperatures are actually more prone to inhibit the recovery effects than higher water temperatures.[14] Higher temperatures around 15 degrees Celsius (60F) and a shorter immersion time of 10-15 minutes accomplish the best effects.

Caveat: one of the only circumstances in which to use cold bath therapy is right after exercising is during high temperatures.[23] In that case, you'll only use cold as a cool down.

Some studies do show a benefit to cold on both soreness and recovery after exercise.[9-12] One mechanism by which soreness may be decreased is through increasing pain tolerance - a topic I'll get back to soon. 

Additionally, overall fatigue is also reduced.[11] Heart rate variability - which measures the time between your heartbeats - increases.[38] A higher heart rate variability is an indicator of having lower stress levels.

Bottom line: some studies do show a positive effect on recovery after workouts, while others don't.[46; 47] Improved study designs in which cold is used on off days will almost certainly demonstrate superior results from cold exposure.

Let's now move to well-proven benefit that everyone needs: 



An increase in stress hormones is one of the mechanisms by which you'll feel better during cold exposure.[67]  

Adrenaline is an example of such a hormone. And while I don't recommend chronically increasing adrenaline levels, using cold intermittently is great if you properly recover. The danger with increasing adrenaline though, is that you'll push yourself too far - beyond your ability to recover.

In terms of cold exposure intensity, giving one-size-fits-all recommendation is impossible: you might be able to expose yourself to 5 ice bath sessions per week, while your friend can only handle 2 sessions (or vise versa).

So let's further explore cold's effects on mood:

Many brain signalling substances increase in quantity with cold exposure, such as "dopamine". Dopamine makes you motivated, happy, and assertive - all things that make life worthwhile.

And you know what?

Intense cold exposure can increase dopamine levels by up to a whopping 250%.[68]

Applied excessively, however, cold has the opposite effect on dopamine.[69] 

The paradoxical result is that you can handle more cold with less stress the more frequently you apply it. The first ice bath you'll ever take will shoot the adrenaline through your body. After taking many ice baths and building up tolerance, however, the stress response is dramatically reduced.

Fascinating fact: dopamine is extremely central to your body's response to cold, as inhibiting dopamine functioning in the brain makes rats unable to adequately heat themselves up.[70]

Higher dopamine levels are also associated with greater mitochondrial mass, i.e. more energy producing factories in your cells.[111] Brown fat also contains many mitochondria, and having more mitochondria in your body may thus indirectly support dopamine levels.

Hence, evidence exists that the state of your mitochondria is related to your overall well-being in life.

a happy smiling dolphin in the water
How you'll feel after getting out of the cold tub...


Moving on to a related benefit:



Cold showers have been proven to work to avert depression.[202] Cold bath therapy is simply a more intense form of cold showers, and by logical implication, will thus have the same effects. 

The study investigating the effects of cold showers on depression speculated that a lack of hormesisi.e., a lack of temporary stress - as partially explaining why depression is so prevalent in modern society.[202]

I wholeheartedly agree with that statement: many people don't challenge themselves and their bodies at all anymore, thereby becoming weakened in the process.

Now, the other side of the equation is chronically putting yourself under too much stress - I've been guilty of that as well, training 6 days a week for 2 hours a day for years on end. Both extremes are dangerous.

And sure, chronic psychological stress through rumination is even more dangerous, and should be completely eliminated. Psychological stress through rumination has no benefit, and makes you weaker, dumber, and fatter. 

Cold therapy has additional benefits besides hormesis though: cold also helps create "beta endorphins", natural opioids that reduce pain sensations and make you feel good. You'll often get the same feeling after intense exercise.

Bottom line: the right amount of cold therapy makes you feel great if you don't overdo it. 

Let's subsequently consider a benefit that helps many people: 



Yes, really.

One mechanism by which cold baths reduce pain is by inhibiting nerve conductivity.[18; 222] Even though there's no certainty, lowered nerve conductivity may be associated with an increase in pain tolerance and decrease in experienced pain.

The reduction in pain may also be responsible for the reduction in soreness after exercise.[34-38; 40] You can even use cold water immersion as a means to reduce soreness, at the cost of adaptations, to temporarily increase performance. That boost in performance may be strategically useful if you're competing in sports, for example.

Now you know why cooling works so well after you've sprained an ankle. Contrary to my expectation and experience, cold water immersion does not decrease muscle stiffness though.[39] 

So let's move on to the next subject:

a happy dog that is really relaxed
Pain human? Never heard of that word...




Colder temperatures can restrict blood flow and fluid exchange in both the lymph system and very small blood vessels (capillaries).[16]

That dynamics is complex, however, because cold water therapy can also open up blood vessels. 

If I'm sitting in my ice bath for some time, blood flow is usually reduced at first (depending on the temperature). That effect can be understood through the fact that cold exposure lowers heart rate, which subsequently lowers overall blood flow.[20]

After some time, however, blood flow dramatically increases, even to my hands and feet. In that case, the body notices that peripheral tissues are getting cold, and attempts to protect them.

But if I'm staying inside the bath for very long, peripheral blood flow decreases again. That decrease then leads to my hands and feet getting coldest first. After intense cold water therapy sessions, my body's entire skin also becomes red from an increased blood flow. I experience that increase in blood flow almost every time.

Over the long term, blood flow to the feet and fingers thus increases.[154] Some contrary evidence exists though, suggesting that feet and fingers can actually adapt pretty poorly to increased demands due to cold exposure.[197]

Lots of scientific debate currently exists around how peripheral parts of your body respond to cold, and the question is not settled yet. In my experience, peripheral blood flow is hugely dependent on your overall health.

In some conditions, hands and legs are frequently affected by excess fluid buildup, for example.

For that reason it's essential to monitor your peripheral tissues if you're exposing yourself to intense cold: 

If you're frequently exposing yourself to cold then you can become "cold adapted".[164] With cold adaptation you'll permanently retain a higher temperature in your skin during cooling, accompanied with better peripheral blood flow.  

That flow of fluids inside the body may additionally be affected by the physical effects of being submerged in water.[15] Water changes the way gravity and pressure works on your body. 

Fluid may be able to move better from lower body parts to higher ones. Though that mechanism, excess fluid in your body, such as edema, may be regulated by cold water immersion.

Again, some people adapt better to cold than others--it's implementation should be adapted to your unique circumstances.

Let's now consider the reason why many people read about ice bath benefits in the first place:



Some older studies in the 1980s had investigated the effects of cold exposure on fat loss but didn't found any significant effects.[44; 45] Modern understanding paint a very different picture, as cold exposure is widely known for its fat loss accomplishments.

Most studies do not study a direct relationship between cold water immersion and fat loss though. The effects of lowering a building's thermostat is sometimes researched, for example, so that you'll sit indoors at 18 degrees Celsius (~65F) instead of 21 degrees (70F).

That 3 degree temperature difference might seem negligible, but it can have a huge effect on your body composition over time. Body composition signifies the relationship between the amount of muscle mass you're carrying in relation to your fat mass quantities.

In a colder room, your body continually has to keep yourself warm by increasing brown fat activity levels.

And yet, lowering temperatures through the thermostat is not nearly as effective as cold baths. You probably know that you're losing heat much faster in cold water than through the air, and fat losses with cold water immersion are thus exponentially greater.

Mitochondria are the key to understanding the effects of cold. Remember I've talked about both mitochondria and obesity?

Obesity is often intertwined with mitochondrial dysfunction.[95]

How much fat you're burning during a cold session directly depends on your mitochondrial function.  

Mitochondria function will go down when they have access to too much energy at the wrong times of the day, which happens if your day and night rhythm is chronically disturbed.

If you're obese, you're also more prone to have lower brown adipose tissue levels.[117] Cold exposure can build those brown adipose tissues back up.

And remember uncoupling protein 1? The less uncoupling protein 1 is expressed, the more prone you will be for being overweight or obese, and vice versa.[118] 

The upside of cold exposure is that body fat losses are accomplished.

Brown adipose tissue is built up at the cost of white body fat, which improves your ability to regulate your weight at two different levels.[193] Firstly, less white adipose tissue makes you healthier overall, and secondly, more brown adipose tissue accomplishes the same thing.

I'd really love some studies comparing the effects of exercise and cold water immersion for long-term fat loss, to closely study the effects of brown adipose tissue accumulation on overall health. Recall that exercise might not increase your brown adipose tissue stores, because you don't need to rely on that fat when working out in a gym.

A difference between exercise and ice bath benefits is thus expected. 

Compounds called "batokines" can be created by brown body fat, for example, which help you stay lean[65] Such substances can lead to an increase of fat uptake in muscle cells, for example, improving energy availability.

Many people don't know that the body can also store fat in addition to glycogen (e.g. "sugar", or "carbohydrates".)

Batokines also enhance circulation and improve insulin sensitivity, although some of these studies have been carried out on animals.[99-102]

Other effects of these batokines are increasing the activity of the "sympathetic nervous system". The sympathetic nervous system is associated with higher activity levels such as during a fight or flight response.[128; 129] Hence, batokine levels are upregulated during (hopefully) temporary cold stress.

A called "adinopectin", moreover, is also increased with cold exposure, causing even greater fat loss.[223; 224] 

Leanness and cold exposure can lead to a vicious (or virtuous) cycle: the leaner you become, the less insulated your body becomes, and the more you need to rely in brown and beige adipose tissue to keep yourself warm.[167; 168] 

Current evidence signifies that repeated cold exposure does not increase insulation, and achieves the opposite over time as you lose body fat.[187; 189] For that reason you're carrying less brown fat if you're obese than when you're lean.

Recall that contrary to the Neanderthal ancestors I spoke about earlier, humans have a limited capacity to insulate themselves. Losing fat thus entails that you need to use your brown adipose tissue more.

The concept of "resting metabolic rate" can also be connected to fat loss and cold water immersion.

Resting metabolic rate denotes the calories you're burning independent of circumstance. Most calories affected by your basal metabolic rate are allocated towards fundamental bodily processes to keep you alive - including ongoing repair and keeping your brain and heart working properly.

Your resting metabolic rate is thus still active if you're sitting on the couch watching television, thus helping you burn calories like clockwork.

(I've written extensively about the relationship of resting metabolic rate and fat loss in a previous blog post, claiming that keeping your metabolism high is one of the most important features of achieving long-term fat loss success.)

Different populations have different brown adipose tissue levels and resting metabolic rates, and the concepts of brown fat and resting metabolic rate are indeed connected to each other. 

In general, the farther away from the equator your ancestors are stemming, the higher your resting metabolic rate.[167; 169] A higher resting metabolism will simply allow you to better withstand the cold, and boosting that rate will upgrade your fat loss efforts (as long as you're not overdoing it)...

Short-term exposure to cold paradoxically decreases basal metabolic rate just after cold exposure session.[185] The lower temperatures drop though, the higher resting metabolic rate becomes to compensate.

An initial drop of metabolic rate is thus eventually (more than) corrected and for.[187; 188]

a dog that is running on the beach, having too much energy
"Have to run away from that water human, before I get any leaner!" 


And I'm not done yet: 

Lastly, activation of brown adipose tissue is also associated with lower levels of "ghrelin", a hunger hormone.

Lower ghrelin levels allow you to better regulate appetite.[127] Many people who try cold exposure actually experience very profound changes in their hunger levels.

Excessive (read: disregulated) hunger may be one of the biggest problems people have in achieving long-term fat loss.

Bottom line: cold therapy benefits for fat loss are really all-round. But let's move on:



Many studies have demonstrated that cold water immersion lowers inflammation. One reason you'd want to reduce (chronic) inflammation is because it's associated with many disease, including heart disease and diabetes.

Inflammation also plays a role in exercise recovery - inflammation is temporarily heightened after exercise.[218]

A few recent studies, however, question the tendency of cold exposure lowering inflammation.[26; 27] Some studies even show an increase in inflammation in the short-term, while illustrating a lowering effect in the longer-term.[219]

The problem with studies investigating the effects of cold water immersion is that they almost always investigate inflammation after exercise.[220; 221] The effects should be studied independent from exercise, so that a baseline effect can be measured.

Good circumstantial evidence exists to assume that cold bath therapy does decrease inflammation. 

And due to the combined effect of lowering inflammation with the next benefit, cold tub therapy is already worth its weight in gold:



Mitochondria are the energy producing factories of your cells. And by putting intermittent stress on your body, you're able to create more and bigger mitochondria.

More and bigger mitochondria result in higher energy levels. In fact, you could go as far as to say that mitochondria are the main determinant of your overall energy levels.

A protein called "PGC-1α"', or "Peroxisome proliferator-activated receptor gamma coactivator 1-alpha" plays a key role in the new creation of mitochondria. Cold exposure increase the expression of PGC-1α.[41; 42]

Unfortunately, these effects have not been studied in great detail (yet), but promising results can be expected.

Additionally, the aforementioned substance called "adinopectin" can help clear damaged and non-functioning mitochondria, recycling them so that novel ones can take their place.[228; 229] Adinopecitin levels are increased through cold exposure.

Recycling cell components is a problem as most people are sleeping very poorly in modern society. Cell components such as mitochondria need to be recycled to stay healthy and slow down the aging clock...

Mitochondrial health is thus supported by cold exposure at several levels.

a bird as an analogy of animals that have far greater mitochondrial capacity than humans
Birds are mitochondria "kings", as they have many more of them than human beings

(Nerd section: cold water immersion may also increase energy levels through what is hypothesized as the "Hall effect". The human body is not just a bunch of chemicals, but functions on electricity too. Water is a key to semi conduction in humans, and the structure of water may be altered through cold. Cold exposure to the skin may improve electrical conductivity, thereby increasing the capacity of cells to hold an electric charge. That dynamic is likely also affected by light inputs - the human body's capacity to hold red and infrared light increases with colder temperatures. A simple metaphor to understand that process is that by cooling yourself down during sunlight exposure, your tolerance to stay in the sun goes up, because you're no longer overheating.)

Moving on to a related subject:



Remember the PGC-1α or "Peroxisome proliferator-activated receptor gamma coactivator 1-alpha" I just ago?

PGC-1α helps create new mitochondria, and cold exposure specifically helps you create new mitochondria in your muscles.[93]

New and bigger mitochondria directly entail that your muscles are getting stronger. Please keep in mind that bigger mitochondria do not directly entail that your muscles are growing bigger - more mitochondria can increase strength without you having to look like a 300-pound quarterback.

Adinopectin, which I've also mentioned before, is also positively associated with increases in muscular strength, and boosted by cold exposure.[227] The reason is most likely that adinopectin plays a role in clearing out low-quality and damaged mitochondria, replacing them with better ones.

Many people - including me - have experienced increased strength levels after integrating cold tub therapy into their lives for a while. Such increases of strength levels are easily explainable through mitochondrial health.

Almost done...

One last benefit:



Recall that I've stated that white fat had a hormonal function in the body: releasing the "leptin" hormone that tells your brain how much energy is currently present in your body.

Brown and beige fat, however, also interact with bodily hormones.[119; 120]

Higher levels of insulin, for example, reduce heat production by brown adipose tissue.[121] The reason for that effect is probably that colder periods are traditionally paired with a lower availability of carbohydrates, and vice versa. 

Insulin is a hormone that allows carbohydrates to enter cells, and is thus diametrically opposed to colder periods in which humans had to rely more on brown adipose tissue.

(That theory is supported by the fact that a diet that's higher in fatty acids seems to stimulate brown adipose tissue formation - which has mostly been proven in animal studies .)

Now, paradoxically, longer-term exposure to cold may increase leptin levels in the bloodstream (although conflicting studies exist)[235; 236]. Through that mechanism your brain assumes that more, not less energy is available, thereby decreasing the propensity of body fat stores to hold onto fat.

So that's it... 

11 benefits of cold water therapy...

Many currently unproven benefits of cold tub therapy, such as increasing willpower and boosting cognitive performance, can reasonably be expected benefits to exist.

Most people experience huge increases in their cognitive performance after a few cold therapy sessions, and also have greater willpower to force themselves to do difficult or uncomfortable tasks.


Well, getting into a cold bath may be difficult the first few times. If you can learn to accept discomfort and push through anyway, that ability also translates to other areas of your life.

Willpower is very important in modern life. 

Don't like filing taxes?

Push through anyway.

Not comfortable calling someone for a new job?

Push through. You get the point...

Other possible cold therapy benefits include a slowdown of aging,[209-211] increase antioxidant levels,[225] greater bone mass,[212] and decreased hunger sensations.[213] The scope of potential cold bath benefits is amazing.

a man who is standing under a waterfall, which cools him down because of the similarities with cold showers
Get the intensity correct, and you'll do great...


After considering all cold water immersion benefits, let's move on to possible side-effects, and how to minimize these...

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In this section I'll consider possible side-effects of using cold water immersion. Keep in mind that these effects only occur with sessions that are too intense or mis-calibrated.

Mis-calibration means that you're exposing yourself to cold even though you shouldn't - an example is a person with African descent, and mitochondria which cannot uncouple well (and therefore produce much heat), who tries to adapt to five ice bath sessions per week.

Hence: some cold is good, but more isn't always better.

Context is king, as always.

The main reason I'm considering these side-effects is to give you a better idea of what to expect when you apply cold therapy in a stupid way. You'll also learn about some of my stupid mistakes...

I'll begin with the low-hanging fruit:



Hypothermia is the most obvious side-effect of cold therapy.[204; 205] And while hypothermia is possible, it's not probable.


Simply put, if you're staying in cold or icy water for too long, you're going to suffer the consequences. Hypothermia is officially defined as having a core body temperature below 35 degrees Celsius (95F)

The risk of hyothermia can easily be avoided by following my advice in the next section about using the correct intensity for your sessions.

If you're at risk for hypothermia, make sure to get yourself out of the situation that's causing the problem. Water conducts heat very well, and removing yourself from the equation thus automatically solves the problem.

Cover up, dry yourself (wet skin still increases heat loss, especially if it's windy), and gently re-heat.

Don't use infrared for re-heating after you've been overexposed to cold, as you might not be feeling the effects of re-warming your skin. By using infrared to re-heat yourself you can end up with burning wounds (yes, I've been there before too...)

The cold shock response, secondly, signifies the pain you're feeling when entering cold water.[206] Many people start breathing very heavily after entering cold water. The solution to avoiding cold shock is to build up the intensity of your sessions more gradually.

So if you cannot handle 10 degree Celsius water (55F), then start out with 15 degrees C (~60F).

Hypothermia has several stages, and for cold therapy, it's most important to remember the first stage, in which confusion and extreme shivering occur. Measuring your temperature can prevent that first stage.

Surprise, surprise: your body can survive a lot longer in colder temperatures than you'd expect.

People have survived for an hour in water a few degrees above the freezing point (of course, with extreme hypothermia as a result). The average human being can stay longer than 90 minutes in 15 degree Celsius water (~60F) and be fine.

Huge muscles, contrary to body fat, paradoxically increase heat loss because muscles have great blood supply. Blood circulating through muscles will continually cool down, subsequently lower your core body temperature. 

Falling into very cold water is most dangerous, but not due to hypothermia: if you're in poor heath you can end up with ended up with a heart attack due to the cold shock.

Walking on thin ice is literally the biggest risk for ending up with a cold shock response. The resulting heavy breathing due to cold shock also causes people to drown, because you're at risk of ingesting water instead of air. 

Drinking that ice-cold water subsequently leads to an even greater shock response. Drowning due to "breathing in" water is actually the most dangerous risk of death in cold water, not hypothermia.

Counter-intuitive but true. 

Hence hypothermia is not really a side-effect if you're using common sense with cold tub therapy. I've included the hypothermia description anyway because so many people are afraid of that risk.

The concepts of hypothermia and cold shock are also somewhat related in relation to cold therapy: the greater the effect of cold shock has on you, the more careful you need to be to avoid hypothermia.

Again, read the next section on proper cold therapy dosing to avoid any side effects.

a almost frozen lake that can be used for cold water immersion
If you're in good health, you can last quite a bit longer in this water than you'd expect--unless you end up "breathing in" water...




Unlike hypothermia, which mainly occurs due to improper cold water immersion application, frostnip and frostbite are side-effects that more frequently occur.

Frostnip, frostbite and hypothermia are related but not the same thing. You can have frostnip or frostbite without getting hypothermia, for example.[207; 208] 


Frostnip and frostbite signify damaged skin due to local hypothermia. Simply put, when your skin becomes cold, cell damage unfortunately occurs. And when that damage persists, cell death is the result.

Your hands and feet are most frequently affected by frostnip and frostbite, because these parts of your body have the smallest circumference and therefore cool down the quickest. Phrased differently, your upper legs do not cool down as quickly as your feet or hands.

Frostbite is a more advanced stadium of frostnip, and includes permanent cell death instead of the temporary inflammation and redness of frostnip.

At more advanced stages, frostbite can damage underlying tissues, such as muscles, bone, and nerves, which can then die off. Luckily I've never been there before...

But am I talking from personal experience regarding frostnip?

Once again: of course! Fortunately, I've only experienced frostnip (and not frostbite) a couple of times.

The first time happened after cooling down my feet in the snow for about two hours in January 2017. My feet turned purple afterwards, but the damage was gone within a day or two.

The second time occurred when I driving a scooter in cold weather in November 2018 for two hours, damaging the skin of my legs. My legs were the only body part covered with a single layer, and cooled down quickly due to the wind and air resistance.

So when using cold tub therapy, be careful of your hands and feet - even though you may feel fine, these smaller tissues may cool down too quickly. Be conservative in choosing intensities.



Nerve damage has been reported with cold water therapy sessions that were too intense.[21] Nerves that are located close to the skin are most prone for damage. 

If you're staying in the cold for too long, even though your fingers and feet already became numb, you're putting yourself at risk for nerve damage. Contrary to popular belief, that which doesn't kill you can make you weaker.

Nerve damage is interrelated with the previous (possible) side-effect of frostnip and frostbite. For that specific reason, you can lose sensations permanently in your fingers or toes, if nerve damage occurs.

Don't be stupid...

Moving on:



If you've got poor cold tolerance then you've got a huge risk for hyperventilating - or quickened breathing.[15]

The cold shock of entering very cool water often leads to people breathing very quickly. 

Hyperventilation is often intertwined with anxiety, because your body is losing lots of CO2. Contrary to popular belief, CO2 is not a byproduct of oxygen consumption, but integral to your overall health.

Without sufficient CO2, your body cannot use oxygen, and with quick breathing, that oxygen is expelled.

Of course, this specific side-effect only occurs if you're used to being warm all the time and then exposed to water that's very cold for your tolerance level.



If I've not taken a cold bath in a while, I'll breathe much heavier when stepping into the bath than when I'm taking these baths several times a week. If you're not used to any cold at all, stepping into an ice bath can come as quite a (cold) shock.

Panicking is the most dangerous reaction you can have when you're getting into the cold. Falling into the ice in the wintertime is an example of a situation that creates panic.

The panic and anxiety can lead to a vicious cycle of anxiety and hyperventilating, which paradoxically reduces your ability to withstand cold.

Slow and steady breathing conquer the day. 

Again, these side effects of hyperventilation or anxiety mainly occur if you're abusing cold therapy or using it incorrectly.

I'm only including these side-effects so that you'll understand the principle.

a woman who is swimming in cold waterDon't panic. Slow and steady wins out...



Losing consciousness in the cold is the ultimate risk that many people are afraid of.[15]

In fact, I've had family question me about safety my cold bath habit - they thought I could pass out or even die at any moment.

Fortunately, the risk is not that high (and that's an understatement):

If you're staying well below your maximum tolerance threshold, you're not going to lose consciousness or worse. Recall that the human body is capable of surviving quite some time in cold water, which has been anecdotally described by people who have survived a shipwreck, for example.

Of course, the colder the water temperature is, the higher the risk for adverse effects. And yet such instances are really rare.



Data on the interaction between cold exposure and the immune system varies. This immune modulation--unlike many of the previous side effects--can be more dangerous.

In the short-term, cold exposure is like a nuclear bomb that really downgrades the functioning of your immune system.[180-183] In the longer run, however, immune system functioning can increase.[181]

Technically, cold therapy's effect on your immune system is thus both a benefit as well as a side-effect.

Exercise is similar in that mechanism, although that thesis is currently under scrutiny.[184; 195]

When dosed properly, I don't think immune system functioning is problematic. If you're diseased though, I do recommend building up cold exposure very slowly and tracking how you respond in terms of your immune system - a short-term hit to your immune system can create problems.

One last potential side-effect to cover;



Recall that your mitochondria become less efficient with cold exposure, as some energy that's normally generated as ATP now fuels heat creation.

Chronically exposing your body to cold may lower your overall energy creation because of less ATP availability.

One counterargument against that statement is that respiratory proteins in the mitochondria are condensed, so that you'll still end up with more energy even though you're producing more heat. In plain language that means that the respiratory moving closer together compensates for more energy being created as heat.

My personal experience accords to that latter outcome - cold mostly benefits me. But as you'll see now, some unique personal circumstances might lower the cold bath benefits for you:

In some situations, I recommend against using cold therapy for health purposes.

If you've got thyroid issues, for example, your ability to generate heat may be categorically reduced.[134-136] In that case, I'd fix the thyroid issue first before trying cold baths.

Another problem emerges when you're unable to create stress hormones, although such instances are extremely rare.[136; 137] As only a few people are struck by that condition called "dopamine beta-hydroxylase deficiency", this risk is infinitesimally small, but dangerous with cold exposure.

A combination of thyroid problems and an inability to withstand cold, however, is very common.[137] 

Nevertheless, under normal circumstances and with normal usage, side-effects of cold bath therapy should be extremely uncommon. Chronically stressing yourself when you've got no ability to deal with that stress, however, is dangerous.

Do more potential side-effects exist?


In the short term, for example, (cognitive) performance may also go down with cold bath therapy.[194] 

I suspect that very high stress hormone levels are the reason for that decline. My personal experience is that in the longer run, cold water immersion massively boosts both physical and mental performance.

But if I take an ice bath that's too intensive, my brain takes 2-3 hours to fully recover. My thinking gets slower in that instance.

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I'll do a quick recap of why it's great to own your own cold bath therapy tub. That tub you've seen earlier only cost me $400 total.

But the options for doing cold water immersion are endless. People like Tony Robbins have even installed a small cold plunge pool in their back yard - you can imagine that such an option is expensive.

But but before considering several cold therapy options, let's consider proper dosing first.

I've described the cold exposure protocol in much detail in my cold thermogenesis blog post, but I'll quickly recap the main argument here.

For 99% of people, superficial cooling of the skin is recommended. Superficial cooling entails reducing the temperature of the skin to 10 degrees Celsius (55F) at the maximum.

That decline in temperature is extremely safe.

If you go lower than the prescribed 10 degrees Celsius, you're massively increasing your risk for experiencing the side-effects described in the previous section, such as undercooling or frostnip.


Well, "deep cold thermogenesis", as opposed to "superficial cold thermogenesis" can lower your core temperature to dangerous levels, making you more susceptible to side-effects.

I've personally experienced side-effects of making my ice bath sessions too intense. Such effects usually occur after spending too much time in water that's really cold, such as near the freezing point.

The end result of that process was frostnib or superficial frostbite. My skin was red and remained in that state for a couple of days.

If you're older, you may experience that side-effect for an even longer period of time, and permanently damage your skin. 

Water around 10 degrees Celsius (55F) or higher rarely gives any side effects besides slower recovery, no matter how long you stay in them. 

An infrared thermometer is the best way to monitor the intensity of your sessions.

I highly recommend getting the following inexpensive infrared thermometer. No need to buy a more expensive meter, you're just trying to get a basic reading of your skin temperatures.

If you've never used cold or ice baths before, it's wise to start with cold showers and face dunks.

I consider the following progression optimal, actually:

  1. face dunks
  2. cold showers
  3. cold baths
  4. ice baths (optional).

Face dunks are really simple: pour some cold water into a bowl, take a deep breath, and stick your face into the cold water for a period of time.

The process of exposing your face to cold water activates what is called the "mammalian dive reflex".[198; 199] Your heart and breathing rates slow down as a result of that dive reflex. Oxygen is also delivered in greater quantities to your vital organs.

Both your nostrils and face are immensely sensitive to the triggering of that reflex. By using face dunks you can let your body adapt to the cold in a safe way, because you're beginning with conditioning your nervous system.

When doing face dunks, keep your face underwater as long as you can stand. Start very conservatively when putting your face into the water the first few times.

Just learn by studying ducks - masters of the dive reflex:

ducks who are fishing and thereby activating their mammalian dive reflex, becuase they're putting their heads underwater

After getting used to face dunks it's time to transition to cold showers. 

I know...

Very few people love cold showers, and yet, you can and will get used to them after a while. The previous sections have clearly demonstrated that human beings can adapt to the cold over time, thus proving that your (possible) apathy is misjudged.

After getting used to face dunks, you should also be able to face cold showers. If you're afraid or cannot stand cold very well, just start slowly in the beginning.

Don't submerge your head or face under the cold shower at first. Instead, let the water hit your shoulders, back, legs, and torso. Later on, your head can be included.

Again, build up your cold tolerance with showers.

After using cold showers for a while you're finally ready to implement cold baths into your routine.

Water at 10 degrees Celsius (55F) and upward is safest.


Simple: with that water temperature it's very hard for your skin temperature to fall below 10 degrees Celsius.

During that process, it's recommended to test your skin temperature with an infrared thermometer every few minutes.

Again, if your skin temperature falls below 10 degrees Celsius (55F), it's time to get out of the bath. 

I do recommend being careful with cold in the beginning. Even if you think you can last for half an hour in a tub the first time, be conservative. For many people, it literally takes hours to warm themselves up again.

If your day was heavily impacted by a cold session because you're taking 3 hours to recover, then choose a lower intensity next time.

Using your feeling to determine how intense sessions ought to be is a sub-optimal method.

Longer periods at a lower intensity is generally better.

Because your hands and feet have a harder time adapting to the cold, neoprene gloves and socks are highly recommended if you've got problems with blood flow to your hands and feet.

With Raynaud's syndrome", for example, a condition in which your hands hardly get any blood flow at all during cold exposure, I highly recommend these gloves and socks. With such conditions, you're also advised to keep your hands out of the water.

With that intensity determination method for your cold bath therapy sessions listed above, exertion should never exceed that of a long walk.

In other words, you're gently cooling the body just like you're easily walking a few miles. Longer and colder sessions are not always better.

The stipulation of intensity I just gave should be very revealing, being especially applicable if you're struck by a disease.

In other words, if you've got diabetes and a heart condition, I simply do not recommend working up to 50 minutes of cold water at 5 degrees Celsius (~40F). Chronic fatigue and fibromyalgia are similar in that regard--expect more side-effects under such circumstances.

Colder water, however, is a great time management strategy. I prefer water that's around 2 degrees Celsius (35F) any day because my sessions will be over in a whim.

One last thing: the poorer your health, the more important it becomes to eat well before taking a cold bath.

With good health, you may be able to withstand ice baths on an empty stomach. In poor health, don't even think about it.

Eating (animal) protein is highly recommended before any of the aforementioned cold techniques, as protein lets your body inherently create heat.

So let's now consider multiple ways to apply cold bath therapy. Remember the cold tub I used?

again a picture of Bart Wolbers doing cold tub therapy with ice water


That tub has both benefits and downsides. 

Let me explain...

One benefit is that you can buy such a 350+ gallon tub for around $300.  For example, you can buy a 300 gallon stock tank HERE.

The water can be left inside that tub for quite some time during the winter at a high latitude in the Northern equator where I live.

The downside?

You'll have to insert a drain inside the tub, so that it's easy to remove the water. Many people cannot integrate such a drain themselves, so you'll have to ask someone for help.

Another downside is that using such a tub at warmer geographical locations, such as the equator, makes the water automatically warm up during the day. Warm climates make a tub that's outside 24-7 mostly useless, unless you refill water every day.

Many people will use ice cubes as a solution, but that solution doesn't work well with big tubs. I never use ice cubes in my tub, as even 200 pounds of ice cubes won't make a huge impact on the temperature of 300+ gallons of water. Buying 200 pounds of ice in the supermarket is also expensive, and most people can thus not apply this strategy.

Using a tub outside without refilling the water every single day is only efficient if it gets cold outside during the night. And for 6-7 months out of the year, that's the case here in the Netherlands.

From early Fall to mid-Spring, I've got water temperatures at or below 10 degrees Celsius (55F) when I get up in the morning. If the water is frozen, I simply use an axe, break the ice, and sit inside the tub for a couple of minutes.

Done for the day...

Water needs to be regularly refreshed if you want to keep your tub clean.

How often you need to refresh water depends on environmental circumstances.

Where I live, in the Netherlands, algae do not grow during the wintertime due to the cold. The water in my tub is also protected from sunlight most of the time, which helps keep the water fresh.

Due to higher temperatures in the summertime, however, I do need to regularly refresh the water, as algae grow really quickly then.

In general, I do not recommend using any cleaning materials for keeping the water fresh. With a plug, I simply refresh the water once it gets dirty. 

Most of the cleaning products that are used in swimming pools are sub-optimal to your health. Chlorine that's used in many pools is a damaging toxin, for example, affects organ function and breathing capacity.[200; 201]

Another very simple option is to buy a wooden barrel, which are more expensive, but look great in your garden (contrary to my tub):

a barrel that can be used for cold thermogenesis

The downside of using barrels is that they're more expensive, especially the bigger ones. Many people collect such barrels for the aesthetics of their garden, bidding up the price.

Most of these barrels are also small, which makes the water temperature increase too quickly when you're using it. The fewer gallons of water in the container, the more quickly your body temperature will heat up that water, making the cold therapy less effective the longer you're exposed.

I thus recommend paying a higher price for a bigger one if you're using a wooden barrel.

The upside of using barrels is that they're made out of wood, and rarely contain any toxic materials.

Metal tubs made out of zinc or steel are also usable for cold tub therapy.

A big upside of these tubs is that they are grounded to the earth - staying grounded may give much bigger health benefits than if your sessions occur in material that's not grounded.

The big downside about using metals is that they cool you down much quicker than water - in fact, up to 50 times as quick.

Putting cold metal to your skin can be really dangerous, and for that reason I do not recommend using zinc or steel tubs outside the home with lower temperatures, assuming that you keep water inside the tub for some period of time.

Want an inexpensive indoor tub? Buy a freezer:

Fill that freezer with water. In general, the freezer needs about an hour to cool the water down. The upside is that the temperature of this freezer can be regulated relatively simply.

The downside is that a freezer is harder to clean, and that you need an additional filtration system to avoid dirty water buildup. Fortunately, freezers have a drain, so that water can be removed easily.

If it's cold outside, the best option for cold water immersion remains visiting the lake:

a cold lake that can be used as an ice bath

You'll even be grounded in the water, which may yield additional health benefits. Lakes have been used for millions of years for that purpose:

a polar bear that's swimming in cold water, used as an analogy for cold therapy
Leading by example


Got big bucks to spend, and want the high end option? 

A Cold Tub may be the ultimate way of integrating cold water therapy into your life.

If you're interested in a Cold Tub, click the website above and mention my name, "Bart Wolbers". Cold Tub can even get you in contact with me so that I can explain more abou the product.

So why Cold Tub?

The Cold Tub has the humongous advantage of being able to be placed inside your house, and thus integrated into your bathroom, garage, or another location.

A Cold Tub costs anywhere between $10,000 and $30,000, however, but I consider it to be the best high-quality option.

The reason for advocating the Cold Tub is that the water is automatically cleaned, and also because of its extremely high quality construction that's suited for indoor use.

A simple bathtub can also be used, but needs to be refilled with every use. A Cold Tub allows you to keep a steady water temperature for 24 hours a day, 365 days a year.

If I had a Cold Tub I'd set the temperature to 5 degrees Celsius ( ~40F) to allow for quick sessions during the day.

So how often should you apply cold therapy in your life?

There's no one-size-fits-all answer to that question, in my opinion. 

Some people do great using cold every single day, even multiple times a day - but they're a minority. Some people do terrible with cold, and need to slowly dip in their feet, then their lower legs, then their... 

You get the point.

Experimentation is the only way you'll find out.

The possibilities of applying cold to your body are endless.

Many additional options exist...

You can try contrast baths, for example, that alternative between hot and cold water. The benefits of contrast baths are different than those of cold baths, probably having additional benefits to circulation and recovery.

Ice baths may also have different health effects than cold baths - a result I'm personally acquainted with.

My own journey through the cold has been extensive.


Well, I've experimented with cooler temperatures at night, to increase fat burning and sleep quality.

The effects of nighttime cooling on fat loss have been confirmed in scientific studies.[196] 

My personal experience with nighttime cooling is not great, as I lose deep sleep quality when applying too much cold at night.

Slightly cool temperatures are great for my sleep quality, but actually being cold achieves the opposite effect. 

The method of achieving cooler sleeping temperatures is simply opening up a window at night. I've tested that method extensively, during up to 300-400 nights in the Dutch wintertime.

And you know what? You're done reading this guide. There's one last action to take: getting the 30,000 foot view...

Want additional methods to apply cold therapy, if you don't have a tub? Sign up below:



Return To Table Of Contents


Ready to make the leap?

nature is the ultimate cold plunge pool, due to grounding and its zero costs

If so, use common sense. 

Many scientific questions with regard to cold water therapy are still open.

How (the expression of) genetics precisely interacts with cold tub therapy is not completely understood yet, for example.

The exact extent in which cold enhances or inhibits recovery after exercise is not grasped either. 

Most studies on cold therapy are of lower-quality right now. The existing direct evidence, in combination with circumstantial evidence, however, is very promising.

And you know what?

You should be experimenting with cold in your life. 

You'll lose nothing by testing the cold, and the benefits are potentially life-changing. Low intensity cold therapy, as described in this blog post, has few if any risks.

Heck, using cold showers probably saves you money, as you'll save money showering.

Before implementing high intensity cold therapy sessions I do recommend further testing though. You'll want to know how your biology is expected to respond to the demands placed upon it by extreme cold.

In other words, you'll want to know how your biology reacts to cold before turning the furnace on the maximum.

With the proper safeguards in place, cold water immersion can totally transform your life. 

Fat loss, increased energy levels, more muscular strength, deeper sleep, improved circulation, and more...

The potential benefits of cold for your health can be as far-reaching as implementing sunlight for the first time, or trying the diet that's perfect for your unique circumstances.

My final message?

Let's get the party started:

a woman swimming in the ocean as cold therapy

Don't be too late, as the party may have began without you...

For other blog posts, see:

Cold Thermogenesis: Cold Showers and Ice Baths For Amazing Fat-Loss, Energy, Mental Well-Being and Performance

Extraordinary Infrared Sauna Benefits: The Ultimate Guide

Are Tanning Beds Safe For Health? The Surprising Verdict

Conquer (Chronic) Stress: The Ultimate Guide To Stress Relief

Mitochondria: Why Your Cells' Functioning - And Not Genetics - Determine Disease 

For further reading on cold water immersion, consider:

  1. Jack Kruse Cold Thermogenesis Series (who gives a coherent theory on why cold works for health, unlike many other gurus)
  2. Why having a cold office may be beneficial in some circumstances
  3. Dinosaurs went extinct because of darkness and cold
  4. Systematic review: why cold water immersion might not be the optimal choice for boosting recovery
  5. Systematic review: how water temperature affects muscle soreness
  6. Systematic review: the body's physiological response to water immersion
  7. Systematic review: cold acclimation and brown fat activation
  8. Systematic review: brown and beige fat's role in countering obesity
  9. Visionary maker that's very much skeptical of the idea of the universal application of cold thermogenesis
  10. Systematic review: the process of cold adaptation
  11. How Neanderthals were built to resist the cold due to short limbs and stocky physiques
  12. A changing climate contributed to the demise of Neanderthals
  13. Neanderthal anatomy in relation to cold adaptation
  14. Effects of climate on hominin evolution
  15. The advantage of Homo Sapiens over other Homo species
  16. Inuit may have have "borrowed" adaptations from earlier Homo species

once again the Health Foundations Program

*Post can contain affiliate links. Read my affiliate, medical, and privacy disclosure for more information.

Author: Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS).


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