What Doesn’t Kill Us | The Wim Hof Method | Summary | Author Scott Carney




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What Doesn’t Kill Us & The Wim Hoff Method


What Doesn’t Kill Us traces our evolutionary journey back to a time when survival depended on how well we adapted to the environment around us. Our ancestors crossed the Alps in animal skins and colonized the New World in loin cloths. They evaded predators and built civilizations with just their raw brainpower and inner grit. But things have changed and now comfort is king. Today we live in the thrall of constant climate control and exercise only when our office schedules permit. The technologies that we use to make us comfortable are so all-encompassing that they sever the biological link to a changing environment. Now we hate the cold and the heat. We suffer from autoimmune diseases. And many of us are chronically overweight. Most of us don’t even realize that natural variation–sweating and shivering–is actually good for us.

What Doesn’t Kill Us uncovers how just about anyone can reclaim a measure of our species’ evolutionary strength by tapping into the things that feel uncomfortable. When we slightly reimagine how our body fits into the world, we can condition ourselves to find resilience in unfamiliar environments.

The feeling that something is missing from our daily routines is growing and has spawned a movement. Every year, millions of people forgo traditional gyms and push the limits of human endurance by doing boot camp style workouts in raw conditions. These extreme athletes train in CrossFit boxes, compete in Tough Mudders and challenge themselves in Spartan races. They are connecting with their environment and, whether they realize it or not, are changing their bodies.

No one exemplifies this better than Dutch fitness guru Wim Hof, whose remarkable ability to control his body temperature in extreme cold has sparked a whirlwind of scientific study. Because of him, scientists in the United States and Europe are just beginning to understand how cold adaptation might help combat autoimmune diseases and chronic pains and, in some cases, even reverse diabetes.

Award winning investigative journalist, Scott Carney dives into the fundamental philosophy at the root of this movement in three interlocking narratives. His own journey culminates in a record bending 28-hour climb up to the snowy peak of Mt. Kilimanjaro wearing nothing but a pair of running shorts and sneakers.


Humans evolved with environmental stressors, it is good to have them

Modern humans live in an environment so perfectly fine-tuned for our comfort, our bodies rarely ever get exposed to stress anymore. In our distant past, the climate was one of the main stressors our ancestors endured. Cold, harsh temperatures.

It turns out that no environmental extreme induces as many changes in human physiology as the cold does.

So, how did our ancestors survive? The answer is, their bodies were perfectly adapted to meet the challenges. And those genes still exist in our genetic pool, they are just turned off for the most part.

There’s an entire hidden physiology in our bodies that operates on evolutionary programming most of us make no attempt to unlock.

Three types of nervous systems

First, it is important to understand the three types of muscle control that emerge from our nervous system. There are the muscles we can control voluntarily, this part is called the somatic nervous system. Then there are the muscles that we have almost no control over, like the heart, the motion of the vascular system, speed of digestion, and dilation of our pupils. All these for part of the autonomic nervous system.

And then there is the third one, this group is shared between the autonomic and somatic systems. Breathing for instance. Blinking of our eyes. We can perform those actions consciously, but as soon as we focus elsewhere, our autonomic nervous system takes over. This third group is the one very interesting to us because it can act as an interface to train the automatic nervous system voluntarily.

The Wedge

We are able to withstand certain urges consciously. For instance, trying to delay a snooze. Standing in the snow. Taking a cold shower. All those acts demand certain willpower, which enables us to override our natural urges to act.

It seems like a small thing, but it’s a window into the root of a human power, and a place that, if exercised, can help unlock the body’s hidden biology. Freedivers who descend hundreds of feet below the surface of the ocean on a single breath sometimes call it the “master switch”: It’s the point where the body meets the mind.

Any preprogrammed physical response is potentially susceptible to the wedge as long as it has three key characteristics. First there needs to be a clearly identifiable external stimulus. Second, that stimulus must trigger a predictable automatic biological response or reflex. Third, that physical response must elicit a feeling or sensation you can visualize or imagine independently of the external trigger. If the reflex has these characteristics, then using the wedge is as simple as setting up an environmental stimulus and then resisting the sensation that it triggers. Over time it becomes easier to maintain the tension between reflex and mental control.

So training starts with one of the most fundamental human reflexes: the urge to breathe. When the Buddha first taught meditation to his followers, he recommended that they start by watching their breath move in and out of their body. Breathwork is a staple of every yoga class, as students move their bodies in sync with their lungs. The Wim Hof Method tasks students to hold their breath until they can’t take it anymore. And then hold it just a little longer. This is the quickest and probably safest way to build your own wedge.

The urge to gasp for air is not directly linked to the amount of oxygen in the bloodstream. That’s because, for some reason that has been lost in the convoluted process of evolution, the body cannot sense oxygen, only its byproduct. Breathing is a two-part process—inhaling to bring oxygen to the lungs and exhaling to expel carbon dioxide (CO2). When the brain senses too much CO2 in the bloodstream, the chest tightens, vision blurs, and just about every muscle from the abdomen to the forehead clenches down hard. When we talk about this sensation we usually say that we need to take a breath.


However, on a physiological level your body wants to expel CO2. It sounds counterintuitive but it’s easy enough to test. Take a deep breath in and hold it until you feel the urge to breathe. Then release a little bit of air. With less CO2 in your lungs you will feel like you can hold your breath a little bit longer. That’s because you’ve removed a potentially poisonous waste product from your body and your nervous system has turned off the alarm bells.

This basic gas exchange creates an opportunity to trick your nervous system into extending the amount of time that you can hold your breath, thus leading to the very first training technique to crack into your nervous system.

Training the Wedge

First, let’s establish your baseline. Take a deep breath and stopwatch yourself to see how long you can hold it. Write down your baseline. Now it is time to train. Start by sitting or lying down, take 30 deep breaths. Breathe in deeply, but don’t exhale all the way down, just let go. Don’t force the exhale. Then breath in again. Do it 30 times. Pretty soon, especially if you are doing this the first time, you will feel a little dizzy, or tingling sensations. This is completely normal. After 30 breaths your blood will be saturated with oxygen and you will have cleared out most of the CO2 in your system. Now stop breathing and with a full chest hold on and time yourself to see how long it takes you to reach the point where you feel an urge to gasp. Once you reach the point where you feel an urge, or reflex to breath, when you can’t stand it anymore, let the air out of your lungs. It will give you a little more time without having to breathe in.

Most people will have a dramatic improvement in how long they can hold their breath after a few of these cycles.

One remarkable account of the application of the Wim Hoff method

Of course, anecdotes don’t serve as hard evidence. But as new things are explored, anecdotes are usually the first signs to emerge. Here is my favorite one from this book.

Kasper van der Meulen was running a race when six skittish-looking horses trotted in a pack as they passed him. One of them bucked and kicked its back leg into his body. He doesn’t remember the actual strike, nor did he hear the bone in his arm snap. The first thing he can actually remember was the sound of his heart pumping loudly in his ears. When he looked down, he saw a bulge under his forearm, a clear indication that something was seriously wrong. At the very least the arm was broken.

Strangely, in the moment, at least, it didn’t actually hurt. Enough endorphins rushed through his system that he felt pretty, well, normal. But when the woman who had been riding the horse came to him in hysterics asking if he’d broken something, he knew that he would have to get to the hospital. “I’m not a doctor, but . . .” he started saying while dangling the awkward and crooked limb for her to ogle. She filled in the rest of the sentence herself.

With his good hand he fished his mobile phone from his marathon vest (it was somewhere mixed in with a pair of peanut butter sandwiches he’d packed for the race) and called his wife to pick him up. He sounded calm on the phone. So calm that she knew something was terribly wrong, and she broke into tears before he even mentioned the horse. She jumped in the car and sped toward him. Knowing that she was a few miles away, van der Meulen meanwhile started focusing on his breathing. He wanted to be ahead of the pain when it finally did set in.

Van der Meulen graduated with one of the very first groups of instructors Hof certified to teach his method. Where Hof can sometimes get lost in his own subject matter and often talks himself through endless tangents about winning the war on bacteria or the importance of universal love, van der Meulen has the advantage of seeing the underlying principles of a subject and putting them into plain Dutch (and English). It helps that his first job out of college was as a science teacher.


This occupation required him to break down complex ideas into bite-size chunks for middle school students to digest. Before that, however, van der Meulen spent most of his teen years smoking marijuana and playing video games at home. His dietary habits were terrible, and he ate whatever was both available and fast.

By the age of 24 he was so grossly out of shape that he could barely run the length of a city block, let alone a mile. His heart beat irregularly and his blood pressure was seemingly always too high. Worse than that, the 240 pounds he packed on his 6-foot-1 frame made him look a little like Humpty Dumpty ready to fall off a wall. Van der Meulen didn’t feel well and figured that he was just depressed. When a therapist suggested that he might benefit from a little exercise, he was horrified. It was the first time that anyone had told him he was out of shape. But his therapist persisted, saying, “You know, sound body, sound mind.”

So he started making incremental changes to his lifestyle. First with short, breathless runs around the block. Then around the park. He started eating just two large meals a day while fasting the rest of the time. This, he’d read, would help stabilize his insulin production and more closely fit with the patterns that humans evolved with. He also hit the gym. Within 3 years he’d lost 80 pounds. By then he’s wasn’t just running in the neighborhood but covering 60 miles a week on country roads.

Conquering new challenges became a way of life. “I found that as soon as I started doing difficult things that everything else in life got easier,” he says. Eventually he found Hof and everything just clicked. The method fit his new persona perfectly, and he geeked out on the biology and budding scientific literature.

He began running marathons and obstacle course races to test himself even more, and it was on one such 20.5-mile trail run that he came across the six-pack of skittish horses. Less than a mile from the finish line and one painful flash of a hoof strike later he was bleeding on the ground and holding his crooked forearm. Eventually the surge of adrenaline began to subside and he could feel fingers of pain creep across his arm and chest. He redoubled his breathing and the rider who was still with him looked terrified.

“You’re hyperventilating,” she said, no doubt thinking she would need to put a brown paper bag over his mouth to stop him from passing out. Van der Meulen shook his head and asked her to let him concentrate. It took 15 minutes for them to walk to the aid station, and from there his wife brought him to the hospital. By the time he was ready for discharge he was actually kind of cheerful.

An X-ray confirmed what van der Meulen already knew. The ulna—the bone opposite the thumb that connects the hand to the elbow—had fractured cleanly into two pieces. He would need surgery, complete with screws. The doctor told him it would be a long recovery. Furthermore, a large purple horseshoe-shaped bruise stretched over his kidney. A nurse offered him an opium-based pain medication while he waited for surgery, but he turned it down. For him, the broken bone was an opportunity for him to practice pain control. The nurse was shocked. She’d never had anyone in his position refuse morphine, but he did. So, long after adrenaline had blunted his pain, van der Meulen breathed consciously for hours and visualized light moving from his lungs to his arm in lieu of a much easier path to painlessness.

The doctors fitted him with a temporary cast and scheduled a surgery for 4 days later. He spent the evening meditating on his injuries, and when he came in for a follow-up appointment the next day the bruises on his ribs and kidneys were gone. The nurse wondered why van der Meulen wasn’t healing like a normal person.

When he finally was admitted to the operating room a few days later, he turned down the drugs again. Doctors gave him only a local anesthetic as they opened up his flesh to set the bone. A few hours later, when he emerged from surgery, a yellowish incision spanned from his wrist halfway to his elbow with broad, inelegant sutures. A nurse told him that he would have to wait for 2 weeks before they could be removed, but asked him to come back the next day so the doctors could have a look at how the surgery took.

Van der Meulen spent the next 4 hours breathing and focusing on his arm. When he tells me this story, I have trouble wrapping my mind around the amount of concentration it must have taken. The effort was constant, but he tells me that it seemed to pay off. When he finally grew tired and went to bed that night, all that was left were the stitches; the resultant swelling from the surgery had markedly subsided. He shows me pictures to prove it. The next day the nurse was shocked.

“Well that went quickly,” he remembers her saying. “In about two weeks the sutures should start to itch, and then you can come back and we’ll take them out.”

Van der Meulen didn’t have to wait quite that long. Three days later the sutures began to itch, but when he called the hospital they said it was far too early to remove them. So his wife took them out herself using a pair of kitchen scissors. When he finally came back to the hospital for his scheduled appointment, the nurse examined both of his arms but the injured limb had healed so neatly that she couldn’t tell which one had been through surgery without asking van der Meulen. When the doctor looked for himself he shrugged. “You are certainly a medical anomaly,” he told his patient.

Yet for van der Meulen, his experience of healing is not so different from those of other people who have studied the method. Nonetheless, his is a go-to story in all of Hof’s instructor sessions. At one lecture, as Hof sat in the audience evaluating his disciples, van der Meulen explained how he dropped everything in his life for a few weeks and just breathed and willed his arm to get better.


It was exhausting and all encompassing, but the results were real and specific. Hof was almost in tears at the end of the lecture. Not only had he found someone who could help with the growing burden of teaching people the method, he had found someone who understood how the process worked in his own body. It was the same technique that Hof had used when he self-treated his frostbitten feet. “That is exactly how it works!” he said to van der Meulen when the talk was over.




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The study that changed Textbooks

Now let’s dive into some real science. This study is what really directed my attention to the Wim Hof method.

In 2011, Hof met with Dutch immunologists Peter Pickkers and Matthijs Kox at Radboud University after making the outrageous claim that he could consciously subdue or ramp up his immune system at will. It was a claim that was, by definition, impossible. The prevailing medical logic at the time held that there was a firewall between the autonomic and somatic nervous systems.

The immune system wasn’t even supposed to be connected to the brain at all. Nonetheless, Kox and Pickkers were curious, and if anyone could test Hof’s claims it was them. Until this point much of Pickker’s career had been devoted to developing tests that evaluated the effectiveness of immunosuppressive drugs.

While turning off the immune system is not usually a great idea, in some cases—such as when someone gets a kidney transplant and their body might reject the donor organ, or in the face of an aggressive autoimmune disease—there is no other way for a person to survive. In 2011 Kox was Pickker’s graduate student looking to finish his PhD and distinguish himself in the medical community.


The test that they devised aimed to trick a person’s immune system into believing that it was infected with a deadly strain of E. coli. Under normal circumstances, once the immune system detects E. coli it starts to produce antibodies and mounts an aggressive fever response to stop the infection before it spreads. People whose immune systems are already compromised, such as by a drug or sickness, continue on as if nothing happened. So the test he devised for Hof was simple:

He’d inject him with the deadly bacteria and see how he responded.

As I mentioned in Chapter 1, when the team injected the solution into Hof’s bloodstream he showed almost no reaction at all—a result that astounded the scientists and helped earn Kox an award for his PhD dissertation on anti-inflammatory pathways. If the results held up to scrutiny, there would be enormous implications for anyone suffering from an autoimmune disease. However, the scientific community was far from willing to admit to a medical breakthrough or start rewriting medical textbooks. The first and most prevalent criticism of the Pickkers and Kox study was that perhaps Hof was a genetic anomaly. Sure, maybe Hof could affect his immune system, but he was probably just an exception to the rule—some sort of freak of nature, not a miracle worker. So in 2012 Pickkers and Kox designed a second experiment. This time they wouldn’t test Hof. Instead they would tell him to teach other people his technique and see if those students achieved similar results.

At first blush you would think that locating 30 people to volunteer for a bacterial injection that makes 99 percent of people feel terrible would be an uphill battle. But when the Dutch researchers announced the impending study at the university campus and told students that they would have a chance to study with Wim Hof, they fielded more applications than they knew how to handle.


The study split volunteers into two groups. Twelve people in the control group would go about their normal lives in Holland, while the second group of 18 would travel to Poland to study Hof’s techniques of ice baths and breathing for 10 days. Predictably, no one wanted to be in the control group, so Hof volunteered to teach his methods to the people in the control group (those who wouldn’t go to Poland) after the test was over.

One week after I left Poland after summiting Mount Snezka, three instructors flew to the farmhouse and Hof taught the active group three basic techniques: cold exposure in the snow, focused third-eye meditation, and sequential muscle retention after hyperventilation. They climbed up the same mountain that I did and baked in the same sauna. When they returned from their trip the volunteers continued to practice on their own for 5 days before showing up to Pickkers and Kox’s lab for supervised injections. The results were astonishing.

Even after such a short training program the active group showed positive levels of epinephrine as well as an increased amount of anti-inflammatory molecules in their blood. They had fewer fever-like symptoms than the control group experienced, and their cortisol levels returned to normal much quicker. To quote the subsequent journal article from the Proceedings of the National Academy of Sciences: “Hitherto, both the autonomic nervous system and innate immune system were regarded as systems that cannot be voluntarily influenced. The present study demonstrates that, through practicing techniques learned in a short-term training program, the sympathetic nervous systems and immune system can indeed be voluntarily influenced.” This short declarative statement forced the scientific community to completely reevaluate their understanding of the immune system.

The article earned a mention on the journal Nature’s website and caught fire across the internet, lending scientific credibility to Wim Hof’s program. If the finding continues to hold up to scientific scrutiny, then it would seem to have potential implications for a huge variety of illnesses—from autoimmune conditions to diabetes to bacterial infections to food allergies to, well, anything. If not an actual cure for any of these, environmental stimulation adds an important dynamic to the overall picture for treating human illness.




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