Cold plunges have become one of the defining wellness trends of the past decade. Celebrities swear by them, elite athletes post videos of themselves climbing into ice baths after workouts, and social media influencers credit plunging with everything from faster recovery and better metabolism to sharper focus, longer life, and dramatic dopamine boosts. But even as cold-water immersion has exploded in popularity, many scientists say the evidence hasn’t kept pace.

Few people have watched that disconnect unfold more closely than Denis Blondin. The thermal physiologist at Canada’s Université de Sherbrooke has spent more than two decades researching how the human body responds to cold. He still vividly remembers the first time he immersed himself in near-freezing water in 2004—not as part of a wellness routine, but as a volunteer in a study examining how cold-water immersion could safely bring someone suffering from hyperthermia back to a normal body temperature. The experience has stayed with him. “I could feel the warm blood travel to my heart as my blood vessels vasoconstricted from the cold,” he recalls. Though it came as “a major shock” to his system, it also sparked a fascination with cold plunges that continues today.

Blondin isn’t against people talking favorably of the practice. In fact, he’s a fan of cold-water immersion for reasons that often get overlooked—including its accessibility and potential to bring people together. He’s also intrigued by the way shivering forces muscles to work to generate heat, ultimately producing physiological responses that resemble exercise. But he has also become one of its most careful critics and is increasingly concerned by the flood of exaggerated claims that have transformed a once-niche practice into one of the world’s biggest wellness phenomena.

There has been an increase in misinformation and disinformation circulating, especially underplaying the risks associated with cold plunges and ice baths. Trying to separate evidence from enthusiasm—and their conclusions challenge many of the movement’s biggest promises. Major findings increasingly show that cold-water immersion is not universally beneficial for recovery or adaptation.

Nor does the evidence consistently support many of the claims surrounding muscle growth, athletic performance, metabolism, or longevity. Underwhelming at best describes much of the evidence behind many other claims. In some cases, researchers worry that cold-water immersion may even interfere with the very goals athletes are trying to achieve—or, for certain individuals, do real harm.

But it’s not that there are no benefits to a cold plunge. Rather, many of the most ambitious promises have simply outpaced what the science supports.

Blondin traces it to three landmark studies published in 2009 that collectively identified metabolically active brown adipose tissue—better known as brown fat—in healthy adults. Brown fat, the researchers found, burns calories to generate heat when the body is exposed to cold. Those discoveries fueled excitement—especially after influential podcasters including Joe Rogan and Andrew Huberman began discussing the potential health benefits of cold plunges often and at length, Blondin says.

(This is what a cold plunge does to your body.)

Many people assumed these findings meant that regularly taking ice baths would naturally increase metabolism and burn more calories throughout the day. Some also suggested it would improve blood-sugar regulation, enhance insulin sensitivity, and ultimately lower the risk of obesity and metabolic disease. But these conclusions went well beyond what the studies themselves demonstrated.

The COVID-19 pandemic then accelerated the interest in cold plunges, as gyms closed and people began experimenting with ways to stay healthy at home. Meanwhile, social media became rife with videos of people jumping into frozen lakes or challenging friends to endure several minutes in near-freezing water. There’s a certain degree of visibility that goes with cold plunging and a sense of ’embracing the suck’ together.

Indeed, a shared sense of challenge is a big part of the appeal of ice baths, and many participants grow so enthusiastic that “they become evangelistic about it.

Where scientists are pushing back on cold plunges

Perhaps nowhere have researchers challenged conventional wisdom more than in the belief that ice baths help athletes recover faster while making their muscles stronger.
Athletes have long routinely used ice baths after intense workouts to reduce inflammation under the assumption that it would speed recovery and improve muscle adaptation. The idea made intuitive sense as icing injuries has long been used to reduce pain and swelling—an approach that has since been largely replaced.

But scientists now think that inflammation may be part of the body’s natural rebuilding process. It turns out the inflammatory signalling from exercise may be exactly what tells your body to adapt to controlled stress. If you blunt it, you blunt the adaptation. A growing body of research suggests that’s exactly what may happen when athletes jump into an ice bath immediately after resistance training.

(You might be stretching the wrong way, scientists say.)

For instance, a 2024 meta-analysis found “that cold water application actually blunted muscular gains when applied post-workout immediately compared to no application. Another 2025 study found that spending 10 minutes in 50°F water also failed to improve next-day recovery or athletic performance. One reason might be that ice reduces the blood flow that delivers amino acids and other nutrients that are vital for repairing muscles.

Scientists are also pushing back on one of the cold plunge movement’s most enduring claims: that activating brown fat naturally leads to weight loss. While brown fat does burn calories to generate heat, Blondin says many people misunderstand what that means. Brown fat’s primary job is to keep you warm, but burning calories is only one mechanism it uses to do that. What’s more, Blondin says the total number of extra calories burned during a cold plunge appears much too small to produce meaningful or sustained weight loss.

Recent findings have also cast doubt on other metabolic claims. For example, a 2025 study found that cold exposure actually worsened glucose tolerance and insulin sensitivity in many participants.

The same is true for many broader promises surrounding immunity and dramatic performance enhancement—claims remain either mixed, overstated, or insufficiently proven. And scientists are still trying to determine whether short-term physiological changes translate into long-lasting health benefits. “We have essentially no well-powered long-term outcome data, and every claim about improving lifespan, metabolism, or cardiovascular health is being extrapolated from acute or short-term physiological studies in small samples.

The risks often overlooked

While much of the conversation has focused on potential benefits, the risks often receive far less attention—particularly evidence surrounding cardiovascular stress. The initial shock of cold-water immersion can trigger the body’s fight-or-flight response, often causing your heart rate to rise, your breathing to accelerate, and your blood pressure to spike dramatically. Blood is also redirected away from the skin and toward the body’s core.
While healthy people generally tolerate such rapid physiological shifts, they can trigger abnormal heart rhythms, chest pain, or, in rare cases, even cardiac arrest among those with underlying medical conditions.

Urge caution for people with cardiovascular disease, arrhythmias, uncontrolled hypertension, Raynaud’s syndrome, peripheral artery disease, seizure disorders, cold urticaria, and several other conditions. For such people, the cardiovascular risks might be too great.

Your heart isn’t the only concern. Studies of commercial fishermen who have sustained nerve damage and other dysfunction after repeatedly immersing their hands and feet in cold water over many years. It’s one reason he would never recommend a daily plunge. This especially matters for athletes of sports where dexterity of the hands and feet is so important, such as hockey, basketball, or soccer.

Scientists also know surprisingly little about how age influences risk—though recent research does show some negative effects in children. Don’t do it with anyone younger than 15-16 years old. With their smaller body size and lower ability to generate heat, they will cool down much quicker. Ditto for populations over 70, who tend to be less able to regulate temperature and tolerate sudden physiological stress, he notes.

Where science still supports cold plunges

Still, it’s not all bad news for fans of cold-water immersion, and this kind of scientific scrutiny was to be expected. Once something becomes popular, there is inevitably pushback. Many studies fail to reflect how athletes actually use cold therapy.

Yes, an ice bath may interfere with building muscle if you jump in after weightlifting. But using it strategically during tournaments or heavy competition periods may help athletes tolerate repeated performance demands. In other words, context matters. An athlete competing in a multiday tournament may need to reduce soreness quickly, so they feel fresh enough to perform the next day again.

Science also supports a handful of other claims about cold plunges. For one, while the physiological stress response triggered by cold exposure may harm people with certain heart conditions, it can also increase alertness. Many people experience this alertness as increased energy, mental clarity, and heightened focus immediately after immersion. Using cold water to improve mood and even depression symptoms is “looking very promising” as a growing area of research.

Several comprehensive studies also suggest that cold-water immersion may improve sleep, particularly after strenuous exercise, in part because a drop in core body temperature is one of the body’s natural sleep signals.

If you’re going to take the plunge…

If the science offers one clear lesson on how to reap even the smallest benefits, it’s that colder or longer isn’t necessarily better. There is still no consensus about the best temperature, timing, or duration.

Duration matters as well. The main effects—which we think provide the benefits—happen within the first two to three minutes. And staying in longer could potentially negate some of those benefits. It’s analogous to doing exercise where the microtears in your muscles generate growth—but overdo it and you damage your muscles. Cold plunging more than once a week is usually unnecessary. Not that cold, not that long, not that often.

Participants should also never plunge alone, especially in natural bodies of water where cold shock can impair breathing or swimming ability.

No wellness practice should replace the basics. “As a sports cardiologist, most of my patients are high performers who want every possible edge. But first show me that you’re consistently exercising, sleeping seven hours, eating well, and avoiding harmful substances and behaviours—because until that foundation is genuinely solid, we can’t talk about the edges. The most evidence-based takeaway is that cold plunges are neither miracle cures nor meaningless gimmicks.”