Technology as a crutch


The industrial age started in the late 18th century in the United Kingdom and with it, brought about technologies that now keep us in the Goldilocks zone, not too hot not too cold. In effect, we outsourced a fundamental aspect of what it means to stay alive and well

temperature control


Specifically, we now do very little cold thermogenesis. It’s a process mammals like us use to produce heat in order to stay warm. Our bodies keep temperature tightly regulated in the range of 36.5 to 37.5 °C (or 97.7 to 99.5 °F).

If you get too cold, entering a state called hypothermia, the molecular machines (enzymes) that run you metabolism can’t function properly – all it takes is a drop of 1 to 2 °C (or 1.8 to 3.6 °F) to get you into serious trouble.

You want cold thermogenesis to kick in before that.

The same goes if you get too hot. You cross the fever threshold when your body temperature reaches 37.2 to 37.7 °C (or 99.0 to 99.9 °) . Get above that and you’re courting risky business.

Fun fact: strictly speaking, not all of your body is at the same temperature. Yes yes, your toes might be cooler than your armpits, but that’s not what I’m talking about.

If you zoom into your cells and measure the temperature of mitochondria, the bean shaped factories producing the ATP you power yourself with, they can reach 50 °C (or 122 °F) – hot damn!

Enter The Iceman: taking back cold thermogenesis


Science advances in strange ways. Progress happens in fits and starts, from glacially slow collaborations to dogged individual pursuits.

The Iceman, also known as Wim Hof, embodies the latter kind.

A 40min Vice documentary well worth your time details the Dutchman’s fascinating story.


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He holds 26 world records , like climbing Mount Everest in nothing but shorts and shoes, swimming 57.7m under ice holding his breath and staying immersed in ice for 1 hour and 52 minutes.

He can do all of this because of his ability to kick-start cold thermogenesis, effectively controlling his body temperature.

We know this because when he stays immersed in an ice for, say, 30min, his body temperature does not drop.

In fact, when he was monitored during his record breaking nearly two hour ice immersion, his core body temperature increased and stayed there until he decided to step out of the icy box.

But how did he maintain and even increase his body temperature in the freezing cold?

Controlling something that acts involuntarily?


We have this thing called the Autonomic Nervous System (ANS). Autonomic means ‘involuntary or unconscious’. It takes in signals from your brain and with its tentacle like nerves invades the heart and other organs, thus making your heart beat and breath go on without you having to consciously think it every time.

Our thermostat too is under its direction, as is thus our ability for cold thermogenesis.

Naughty Wim Hof showed us something about the ANS he was wasn’t supposed to…sometimes it’s not totally autonomic.

By simply breathing in deeply and then exhaling some but not all of the air out, we can change ANS activity

This is what the breathing pattern looks like

Subjects also hold their breath at the end of a breath cycle (either with or without air in their lungs), hence the labels of ‘hyperventilation’ followed by ‘retention’ in the image above.

What ANS mediated things can change after repeating these cycles of ~ 30 breaths a few times?

  • Raise the hormone and neurotransmitter epinephrine
  • Attenuate the proinflammatory innate immune response
    • Raise the anti-inflammatory factor IL-10
  • Spurs cold thermogenesis, maintaining or increasing core body temperature
  • Supersaturate blood oxygen levels
  • Increases blood pH (makes it more alkaline)
  • Increase or lower the heart-rate

Medical textbooks are being literally re-written in order to include the finding that the ANS can come under some degree of conscious control.

This list of physiological changes probably isn’t exhaustive as these are the only ones measured in a proof-of-principle study done in 2014 at the Radboud University Medical Centre in the Netherlands . There may be more!

So is this data about a single freak individual with an rare On/Off switch for cold thermogenesis? No, he teaches this simple breathwork to others, revealing their own ability to exert control over their ANS.

The Radboud University study collected data on 24 randomized subjects, 12 were controls and 12 were recently ‘trained’ individuals in the breathwork. It’s relatively easy to learn, is free and has a wide scope of potential applications – all of which makes it particularly exciting!

Much ado about epinephrine


This type of breathwork releases a lot of epinephrine – how much? Lets use a comparison to illustrate the point. A 2011 study found bungee jumpers had about 1.25 nmol/L of epinephrine on average just before their jump .

The trained subjects in the Radboud University study produced 2.08 nmol/L of epinephrine on average, and some individuals peaked at 5.3 nmol/L! Remember, they were just lying down in a comfy hospital bed doing a few cycles of the breathwork, not jumping off a cliff held only by a stretchy rope.

Speculation about the effects of raised epinephrine


I buried the lead. The Radboud University study did something pretty cool.

They injected the 12 control and 12 trained subjects with lipopolysaccharide (LPS), that which coats bacteria and is recognized by your innate immune system so you can react appropriately to invasions from foreign organisms.

When you inject ‘normies’ (the control subjects) with LPS, they develop a fever, shiver, feel achy, nauseated and have a headache.

They’re in effect suffering from endotoxemia. The trained subjects had much less of these symptoms, they were much milder around 56% less.

Why did the trained subjects not suffer full-blown endotoxemia upon having LPS injected into them?

It probably has a lot to do with epinephrine. It’s still early days, so the mechanisms aren’t all worked out. Nevertheless, the current picture indicates that

  1. cycles of hyperventilation + hypoxia (from a temporary lack of oxygen to due to holding one’s breath) increases epinephrine levels
  2. increases epinephrine levels inhibit the production of IL-10

IL-10 is one of the factors in your innate immune system that usually increases a lot when LPS is detected in your bloodstream, where it shouldn’t be.

It’s maybe not all about the breathwork though. It seems that cold-exposure with subsequent rewarming may also play a role in dampening the immune system’s response to LPS.

The authors of the Radboud University study speculate this can prime the vascular system and/or release DAMPs (Dangers Associated Molecular Patterns), in effect better preparing your immune system to respond effectively to foreign invaders like bacteria.

In other words, it appears that effective cold thermogenesis, whereby a warm core body temperature follows an initial cold shock, may prime the immune system for dealing with foreign organisms.

Dr.Cold may help you with your type 2 diabetes


In 2015 a study came out reporting the effects of short-term cold exposure on 8 overweight type 2 diabetics .

After taking baseline readings of their insulin sensitivity, a key metric indicating the severity of their diabetic state, for 10 consecutive days they were exposed to temperatures of 14 to 15 °C (or 57 to 59 °F) for 2 to 6 hours a day.

Nothing else was changed, not their activity, food or sleep. After these 10 days, their insulin sensitivity was measured again. This study focused on the particular effects of cold thermogenesis, without the breathwork.

On average, these 8 overweight diabetics saw their insulin sensitivity improve 43% !

Currently there is no drug for diabetics than can have such a profound effect on insulin sensitivity, and even less so without bringing on a slew of side-effects. Now, this is just a pilot study. We don’t know if physiology adapts back to the pre-cold exposure state. We don’t know how universal this is. Nevertheless, it’s exciting!

This paper is full of other gems regarding how cold affects our biology

  • cold thermogenesis spurs the creation of brown adipose tissue (BAT), the kind of fat you to have because it generates heat (without the need to shiver) and isn’t associated with nasty inflammatory molecules that excessive amounts of white adipose tissue (WAT) releases
  • the cold also makes your muscles take up the sugar circulating in your blood more effectively
  • the cold appears to reduce the quantity of non-esterified fatty acids (NEFAs) circulating in your blood, something that’s often too high in overweight diabetics



Be skeptical of claims relating to how a simple breathing protocol can induce and clinically meaningful changes in your biology.

But, these claims are being tested by science and so far so good. Furthermore, you can test them out on yourself, check out Wim Hof’s online program Inner Fire.

You can pay for the course or just practice the breathing technique on your own for free. The breathwork is simple and a cold shower is all you need to test your ability to turn on cold thermogenesis.

If you want more details on the study looking at how 8 overweight diabetics responded to cold exposure and what it did to help their disease markers, check out episode 14 of the Break Nutrition podcast.

There’s also a follow-up study to that one with more participants, it’s worth checking out. As always, consider drug and non-drug interventions to manage your health, learn about the science and when feasible, test it out yourself.

Do you have a breathing practice? How do you handle the cold? What leaves you skeptical about these cold exposures or breathworks? Let us know in the comments below.


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