Wim Hof, a 57-year-old who goes by the nickname “The Iceman,” holds 20 Guinness World Records for withstanding extreme temperatures. He’s run barefoot marathons in snow, dunked himself naked in freezing lakes, and climbed Mount Kiliminjaro dressed only in shorts. Today, he instructs classes in the Wim Hof Method to students like surfer Laird Hamilton, claiming that exposure to cold, meditation, and special breathing techniques can essentially hack our immune and nervous systems, shedding pounds and improving health and energy.

A few years ago, investigative journalist Scott Carney flew to Poland to meet Hof, planning to expose him as a charlatan or madman in a piece for Playboy. “He seemed to be claiming superpowers,” recalls Carney. “Like conquering the world’s tallest mountains with no cold-weather gear, controlling his body temperature and immune system at will. I’d built my career debunking men like him.”


[quote position=”left” is_quote=”true”]Our lifestyles are just too antiseptic and comfortable now.[/quote]

Instead, Carney says that he dug into the science driving Hof’s health claims and found that he was the real deal, zeroing in on simple but profound techniques that allow us to turn the extremes of our environment to condition our bodies and renew our lost evolutionary strength. After meeting Hoff, Carney says, “I hiked to the summit of Mt. Kilimanjaro without a shirt. I sat on the snowy bank of a river until the ice melted around me.”

After turning his experience into the book What Doesn’t Kill Us: How Freezing Water, Extreme Altitude and Environmental Conditioning Will Renew Our Lost Evolutionary Strength, out this month from Rodale Books, Carney spoke to GOOD about just how healthy it is to go extreme.

In 2013, you first flew to Poland to meet Wim Hof as a skeptic. Can you tell us about those early days?

I was living in Long Beach, California, had a belly paunch, backaches, and thought my days of youthful adventure were fading fast. Then I saw a picture of a nearly naked man sitting on a glacier. I thought maybe Hof had some very special physical abilities—perhaps genetically bestowed—to be able to endure the ice. But when he started suggesting he could teach people the same techniques, I was wary. I didn’t go to meet him with the intention of changing my health. I went to expose him as a charlatan. But instead I learned that his techniques are teachable, and that he has unlocked some ways for us to use the environment to stimulate our innate immune system.

In your book, you talk about the scientists who have studied Hof’s abilities. What did they find out?

In 2007, at the Feinstein Institute for Medical Research on Long Island, Hof was studied by Kenneth Kamler, a doctor who has worked on Everest. Hof was connected to heart and blood monitors and immersed in ice. Hof stayed in the ice for 72 minutes. His heart rate went down to 35 beats per minute. His breathing slowed down to once every few minutes. His core temperature initially declined a few degrees, but then rose again. Later, Peter Pickkers, a research scientist at Radboud University Medical Center in the Netherlands administered a harmless toxin (one made by the common E. coli bacteria found in our gut) to Hof. Ninety-nine percent of healthy people react with flulike symptoms to the toxin before their body realizes it is actually not harmful. Hof did not react with flulike symptoms, he had only minor headaches. Blood drawn while he was meditating remained resistant to the toxin for six days after it had left his body.

You point out that Hof might have unique abilities, perhaps some of them genetically bestowed.

Hof’s ability to withstand long exposure to cold might be partly due to the fact he has larger than usual amounts of heat-generating brown fat. His identical twin brother André also has the same high amount. They were both studied by scientists in the Netherlands.

But he was actually able to train volunteers to regulate their immune systems, right?

Yes, he trained twelve healthy volunteers in his method. They received injection of the toxin, and the trained volunteers were able to keep the body’s reaction at a far lower level than their untrained counterparts. An anti-inflammatory molecule called interleukin-10 increased more rapidly in the trained volunteers, while inflammatory molecules were lower.

How would you describe your health today, after learning Hof’s method?

I can’t claim that what I’ve experienced will apply to anyone but me, but my metabolism has changed pretty radically. I used to wear size 36 pants and now I wear size 31. I was given a treadmill test by Rob Pickels of the CU Sports Medicine and Performance Center in Boulder, Colorado. My bloodwork showed that when I exercise, I burn fat, not carbohydrates. I’ve added the equivalent of seven hours of exercise to my weekly routine, but actually my total exercise is about three hours a week. I was always afflicted by painful mouth canker sores, since I was a kid. After using Wim’s cold-exposure techniques, I haven’t gotten a single canker sore. That’s a small thing, but I’ve met people who have reversed rheumatoid arthritis or Crohn’s disease using his approach.

What is the scientific explanation for all of this?

We have this underlying biology that’s very adaptable and survival-oriented, but these days we are cocooned in comfort and we don’t activate it. So we’ve broken our fundamental biological links to the world around us. Indoor plumbing, heating systems, grocery stores, cars, and electric lighting now let us control our environment so thoroughly that we can live in perpetual homeostasis. But we evolved differently. We evolved to survive variations in our environment.

[quote position=”right” is_quote=”true”]In one study, overweight diabetic men were put into a cold room and their insulin resistance improved.[/quote]

Think of our ancestors who mounted expeditions across frozen mountains and parched deserts with only a whisper of technology to aid them. Simply reintroducing some common environmental stressors can bring back some of our lost evolutionary vigor. There’s a hidden biology we can tap into. We need environmental and physical variations that invigorate our nervous systems. We are living today with an evolutionary mismatch. Ray Cronise, a former NASA scientist, says we’re overlit, overfed and overstimulated.

What does cold do for us?

First, it activates and increases your brown fat (BAT). BAT is a type of fat that the body uses to generate heat. So brown fat boosts our metabolism and burns calories. It stimulates your body to generate more muscle mitochondria, the energy powerhouses inside your cells. In one study, overweight diabetic men were put into a cold room and their insulin resistance improved.

Why would someone’s immune system improve?

We don’t have all the science yet, but I can speculate that it’s because your nervous and immune systems are connected. That’s been proven scientifically, and we also know it from the simple fact that when you’re in better spirits it’s harder to get sick. But if you’re depressed and stressed you’re likelier to come down with a cold. The way I look at it, our lifestyles are just too antiseptic and comfortable now. These cold showers and strenuous breathing techniques essentially give our immune system something to occupy it so it doesn’t turn on itself.

[quote position=”full” is_quote=”true”]You have to realize that your fear around this momentary discomfort—a discomfort that will definitely be there—is mostly in your mind.[/quote]

What is your routine these days?

I do his deep-breathing routine for 15 minutes every morning. The technique is outlined in my book, but it involves multiple rapid breaths followed by breath retention. I do 50 pushups while holding my breath. When I get in the shower, I expose myself to one minute of cold water at the end. The intensive cold shower or ice water activates your nervous system immediately. I keep the temperature of my home in the low 60’s. Just keeping the temperature of your home low is like doing a low-grade workout all the time. Your body has to work a little to keep warm. You can actually lose weight by dialing your thermostat down like that. And I run outside shirtless two or three times a week, no matter the temperature.

How did it feel climbing Mt. Kilimanjaro in shorts?

It was awesome and exhausting, but very liberating. The interesting part is not being shirtless. The interesting thing is the speed at which we did it, which was five times faster than the normal ascent. We did it in only 28 hours. Usually people go slowly because they have to acclimate to the altitude change. The peak is around 18,000 feet. Forty percent of climbers fail because of acute mountain sickness. In fact, some mountaineers called our climb a suicide mission. But the key was that we compensated with Wim’s breathing method. His method increases the rate of respiration and adds more oxygen to your tissues, and we did the breathing technique long before we had to. So we had enough oxygen in our systems to quickly climb. If you apply that concept to regular exercise, you want to breathe heavily before you get to the maximum exertion, before you feel you have to catch your breath.

In your book you say, “I don’t like to suffer. Nor do I particularly want to be cold, wet, or hungry. If I had a spirit animal it would probably be a jellyfish floating in an ocean of perpetual comfort.” Most of us are like you. What do you say to those who’d like to feel healthier, but shiver at the mere thought of getting icy water?

You have to realize that your fear around this momentary discomfort—a discomfort that will definitely be there—is mostly in your mind. If you’ve gone through your whole life and never been exposed to big temperature variations, then experiencing cold is going to be like going to the gym your first time. Of course it’ll hurt—I’m not going to sugar coat that for people.

But what’s exciting is that you’re suddenly opening your body to a new type of experience, and you will see very rapid changes in your physiology. Pretty quickly you’ll start to feel euphoria as you release all these hormones like cortisol and norepinephrine. It’s like a runner’s high. It’s a natural response.

What’s your final takeaway?

No environmental extreme induces as many beneficial changes in human physiology as the cold does. Use it.

  • Can’t stop endlessly scrolling? Tips to help you take back control
    Photo credit: milorad kravic/Getty Images
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    Can’t stop endlessly scrolling? Tips to help you take back control

    Social media is designed to be addictive, but there are ways to break free.

    It’s called the infinite scroll – a design feature on social media, shopping, video and many other apps that continuously loads content as you reach the bottom of the page. Handy? Yes. Clever? Also yes. Devious? Very much so. The infinite scroll is likely the main reason you find it so hard to stop scrolling once you begin.

    To understand why this design feature is so devious, we need to understand the psychology and behaviours it taps into.

    First, the infinite scroll takes away a natural stopping point – where you might decide that’s enough social media for today. For example, Instagram feeds once stopped after all chronologically new posts from followed accounts had been viewed, and even told us we were “all caught up” for the day. Now, algorithmic feeds combined with the infinite scroll mean there’s no way to ever be caught up with it all.

    The second reason you find it so hard to stop scrolling is the promise of something good that might be just about to pop up in your feed. The algorithm “knows” what you like. So, hand-in-hand with the infinite scroll, it keeps feeding you all those tasty tid-bits.

    Putting it bluntly, these features help create an addiction of sorts. The promise of a little hit of dopamine when we see content we love. And addictions are hard to beat – but not impossible.

    Here are some quick wins and longer-term solutions if you want to break free from the grip of the scroll.

    The quick wins

    Create a break

    Your device might be the problem, but it can also be part of the solution. Start by using your phone’s screen time features – such as Android’s Digital Wellbeing or Apple’s Screen Time.

    You can also install a more sophisticated third-party app that forces you to break the patterns of mindless scrolling behaviour.

    Apps such as One SecScreenZenOpal and Freedom can short-circuit the automatic habits associated with scrolling in various ways. These include putting mandatory pauses before social media apps open, or applying colour filters (like grayscale) to make apps less appealing.

    They can even hard-block apps for specific periods of time if you really need a tough love approach.

    Remove social media apps

    This one’s usually met with an audible gasp when I suggest it, but you might find you adapt to not having social media at your fingertips faster than you’d imagine. You’re not deleting your accounts – just making it harder to open them and scroll.

    Schedule some scrolling time

    If you can’t imagine life without scrolling, schedule time each day for just that activity. It could be in your lunch break or when you get home from work: give yourself the freedom to scroll for the amount of time you set (say, 15 minutes) and don’t feel guilty about it. Just remember you still have to close the apps and get on with your life as soon as the time is up.

    The hard work

    The above might limit your scrolling in the short term, but long-term benefits (and emotional freedom) will likely take a bit more work.

    The “easy” tips often work for a little while, when you’re motivated to change and feeling optimistic. But time and the pressures of life can start to erode your convictions.

    So, to gain true freedom from scrolling, think about social media and whether it’s a relationship that serves you well. If you feel like it’s controlling you far more than you are controlling it, here are some things to consider. Be warned, they might not be easy.

    What’s the deeper reason?

    Think deeply about why you’re scrolling so much in the first place. Is it a lack of willpower? Are you avoiding something or someone? Are you suppressing feelings that you would prefer not to acknowledge?

    All of these things can be reasons why we seek distraction. You might be avoiding a big thing (the state of a relationship) or a small thing (cooking dinner), but either way, scrolling is the symptom, not the disease. So, consider if scrolling might be part of a bigger problem you need to deal with instead.

    Who’s benefiting whom?

    Consider how much you really “need” social media. Do you actively use it in a way that benefits you (for example, as a business platform) or did you sign up out of curiosity years ago and have never really questioned why you’re still using it?

    If it’s the latter, apply a critical lens to the platforms you use and how they serve you. On average, Australians use six to seven different social media platforms regularly. Think about what you might gain from spending less time scrolling, but also think about whether your life would be worse without some of them.

    If you can’t think of a really compelling reason as to why it would be worse, it might be time to say goodbye to a few.

    These “hard” options will take time and effort, and require you to reflect on your habits. But, like with most things, the reward for effort is likely to be greater, and last longer.

    This article originally appeared on The Conversation. You can read it here.

  • Goodbye, knee pain. In a medical first, scientists have found a way to regrow damaged cartilage.
    (LEFT) Person with knee pain and (RIGHT) new bioactive material.Photo credit: Canva & Samuel I. Stupp/Northwestern University
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    Goodbye, knee pain. In a medical first, scientists have found a way to regrow damaged cartilage.

    “Our new therapy can induce repair in a tissue that does not naturally regenerate.”

    Science might be closer than ever to solving your aching knee problems. Researchers at Northwestern University have created a rubbery goo that can regrow cartilage in damaged knees.

    Cartilage cushions joints, keeps movement smooth and pain-free, and reduces pressure on bones—from standing still to a vigorous hike. However, when it’s damaged by injury or simple wear and tear, the road to recovery can be extremely challenging. Cartilage has a very limited ability to regrow and heal itself.

    research, regrow cartilage, recovery, tissue, regeneration
    A doctor examines a knee.
    Photo credit: Canva

    Regrowing cartilage with a rubbery goo

    This breakthrough bioactive material doesn’t just passively sit in the body, it binds to and integrates with surrounding tissue, promoting cartilage regeneration. The substance forms a network of components that imitate the body’s natural environment. A scaffold-like structure allows cells to connect and rebuild cartilage tissue.

    “The problem is that, in adult humans, cartilage does not have an inherent ability to heal,” said Samuel I. Stupp, who led the study. “Our new therapy can induce repair in a tissue that does not naturally regenerate. We think our treatment could help address a serious, unmet clinical need.”

    protein, sheep, bioactive material, damaged tissue, protein fragments
    Damaged cartilage stained red.
    Photo credit: Samuel I. Stupp/Northwestern University

    Bioactive material regenerates high-quality cartilage

    In the study, Stupp and his team applied the material to damaged cartilage in sheep. These animals have weight-bearing loads comparable to human knees.

    The biomaterial, made from short protein fragments and a modified version of hyaluronic acid, behaves similarly to naturally occurring cartilage in the body. Stupp explained the reasoning behind using hyaluronic acid, saying, “It’s also naturally found in many tissues throughout the human body, including the joints and brain. We chose it because it resembles the natural polymers found in cartilage.”

    After fewer than six months, the new cartilage showed high-quality regeneration and strong indications that the repair could work in humans.

    hyaluronic acid, cartilage repair, natural polymers, structure, surgery, regrow cartilage
    Treated cartilage stained red shows repair.
    Photo credit: Samuel I. Stupp/Northwestern University

    Limited solutions to damaged knees

    Cartilage damage is unfortunately very common, affecting more than 500 million people worldwide. For decades, the message has been discouraging: once cartilage is damaged or disappears, it’s gone for good.

    A 2025 study found that current treatments, such as surgery, cell implants, and microfracture, may help in the short term but often produce weaker cartilage soon after. Failure rates for microfracture surgery have led to as many as 41% of patients requiring total knee replacement. Finding reliable, long-lasting solutions is still a work in progress.

    A 2025 study on cartilage repair found that, although many people felt better after surgery, up to 48% developed arthritis over time. Only 17–20% returned to playing sports, and some required additional surgeries, including knee replacement.

    yoga, exercise, standard care, arthritis, goo-like material,
    A woman practices yoga.
    Photo credit: Canva

    Study hopes to change the standard of care

    Researchers believe the bioactive material could be used in most joint surgeries. With these promising findings, the goo-like substance could one day make a meaningful difference for anyone hoping to move without pain again.

    “By regenerating hyaline cartilage, our approach should be more resistant to wear and tear, fixing the problem of poor mobility and joint pain for the long term while also avoiding the need for joint reconstruction with large pieces of hardware,” Stupp said.

  • Menstrual pads and tampons can contain toxic substances – here’s what to know about this emerging health issue
    Studies have found small amounts of toxic heavy metals and other potentially harmful substances in some menstrual pads and tampons.Photo credit: zoranm/E+ via Getty Images

    About half of the global population menstruates at some point in their lives. Disposable products, such as tampons and pads, are some of the most popular products used around the globe to manage menstrual flow.

    Unfortunately, studies have shown that many personal care products, including shampoo, lotion, nail polish and menstrual products, contain hazardous chemicals. Items used in or near the vagina are of particular concern because they are in contact with vaginal mucous membranes – the moist tissue lining the inside of the vagina that secretes mucus. These tissues can absorb some chemicals very efficiently.

    People use menstrual products 24 hours a day for multiple days monthly, over the course of many years. Tampons, which are used internally, are surrounded by the permeable vaginal mucous membrane for up to eight hours at a time.

    I am an environmental epidemiologist, and I study chemical exposure, its sources and its health effects. As a person who menstruates, I also must make my own decisions around menstrual products and manage the challenge of finding accurate information about women’s health risks, which receive less research attention and funding than men’s health.

    In 2024, I co-authored the first paper that detected metals in tampons, including toxic metals like lead and arsenic. My colleagues and I also wrote a review paper that surveyed the scientific literature and found about two dozen studies measuring chemicals in menstrual products.

    The various chemicals that these studies detected were typically at concentrations low enough to make their health impact unclear. However, they included chemicals known to disrupt the endocrine system, which makes and controls hormones that are essential for bodies to function.

    How contaminants get into menstrual products

    The first modern tampon in the U.S. was patented in 1931. Nearly a century later, tampons still are made primarily from cotton, rayon or a blend of the two.

    Chemicals may get into tampons and other menstrual products in a number of ways. Some chemicals, like heavy metals, are present in soil, either naturally or due to pollution, and may be absorbed by cotton plants.

    Other chemicals, such as zinc, may be intentionally added to menstrual products to prevent the growth of harmful bacteria. Still others, such as phthalates – synthetic chemicals used to manufacture plastics – may leach into menstrual products from plastic packaging or be added as part of a fragrance.

    Research suggests that these chemicals are present in a large proportion of menstrual products – we found lead present in all 30 tampons we tested. What we don’t yet know is if these chemicals can get into people’s bodies in a high enough concentration to cause health effects in either the reproductive system or elsewhere in the body.

    Limited federal regulations

    The U.S. Food and Drug Administration regulates tampons, menstrual cups and scented menstrual pads as Class II medical devices, which carry moderate to medium risk. Unscented menstrual pads are Class I medical devices, which are considered low-risk. These categories are based on the risk the device may present to a consumer who uses it in the intended way.

    FDA guidance for Class II devices offers only a few general guidelines with respect to chemicals. For menstrual tampons and pads, it recommends – but does not require – that products should not contain two specific dioxin products or “any pesticide and herbicide residues.” Dioxins are a chemical by-product of the bleaching process to whiten cotton, and they are associated with cancer and endocrine disruption. Using non-chlorine bleaching methods can reduce dioxin formation.

    The most stringent regulation of tampons in the U.S. occurred after an illness called toxic shock syndrome became a public concern in the 1970s and 1980s. Menstrual toxic shock syndrome occurs when the bacteria Staphlococcus aureus grows in the vagina on inserted menstrual products and releases a toxin called TSST-1. This substance can be absorbed through the vaginal mucosa and cause a variety of symptoms, including fever, high blood pressure, shock and even death.

    During this epidemic, in which at least 52 cases were recorded and seven people died over a period of eight months, tampons were associated with the syndrome – especially a highly absorbent tampon called Rely, which was pulled from the market.

    In response, the FDA created a task force that recommended standardizing the tampon absorbencies and advised consumers to use the lowest absorbency for their flow. This is why tampons in the U.S. now come in a range of absorbencies, from light through regular to super and ultra, so that users can choose the level they need while minimizing risk of toxic shock.

    Living in a ‘soup of chemicals’

    Just because a chemical is present in a menstrual product doesn’t mean it can get into the body. However, chemicals like lead and arsenic are known threats to human health. So it’s important to study whether harmful chemicals present in menstrual products could contribute to health problems.

    Humans in the modern world live in what expert toxicologist Linda Birnbaum, former director of the National Institute of Environmental Health Sciences, calls a “soup of chemicals.” Simply being present on Earth means being exposed to many chemicals, at different concentrations, all at once. This makes it difficult to unravel the relationship between a single chemical exposure and health.

    Nonetheless, science has shown that chemical exposure from at least one menstrual product – vaginal douches – does affect health. Vaginal douching is the process of washing or cleaning the inside of the vagina with water or other fluids.

    The American College of Obstetricians and Gynecologists recommends avoiding this process, which can harm healthy bacteria in the vagina, increasing the risk of vaginal infections and other diseases.

    In addition, a 2015 study found that women who use vaginal douches have higher concentrations of a chemical called monoethyl phthalate in their urine. Exposure to this substance is associated with reproductive health problems, such as reduced fertility and increased pregnancy risk.

    Can these chemicals be absorbed?

    Scientists are working now to determine what concentrations of metals and other chemicals can leach out of tampons and other menstrual products. One 2025 study estimated that volatile organic compounds, a group of chemicals that vaporize quickly, can be absorbed through the vaginal mucosa. Volatile organic compounds may be added to menstrual products as part of fragrances, adhesives or other product components.

    My team and I are now shifting our focus to the relationship between menstrual product use, various chemicals, and menstrual pain and bleeding severity. We want to see whether some chemicals will be elevated in menstrual blood, whether these chemical levels are higher in people who use tampons, and whether the chemicals are associated with greater menstrual pain and bleeding.

    States are starting to act on this issue. For example, in 2024, Vermont became the first U.S. state to ban multiple chemicals from disposable menstrual products. California bans PFAS, a widely used group of highly persistent chemicalsfrom menstrual products. New York adopted a law in December 2025 barring multiple toxic chemicals from menstrual products.

    California also enacted a law in October 2025 that requires manufacturers of disposable tampons and pads to measure concentrations of arsenic, cadmium, lead and zinc in their products, and to share those measurements with the state, which can publish them. More information like this will help support informed choices for millions of consumers who rely on menstrual products every month.

    This article originally appeared on The Conversation. You can read it here.

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