Everyone from Andrew Huberman to Bryan Johnson to your neighbor’s Instagram feed is telling you to get in the cold water. Cold plunge tubs are selling for $3,000 to $15,000. Amazon went from selling under 1,000 units in November 2022 to over 90,000 units twelve months later. The global market hit $870 million in 2025.
The influencers are not making it up. The physiology is real. Cold water does things to your body.
The question your MED Report filter asks is not whether cold plunge works. The question is whether it works enough to justify what you are being asked to spend, in money, space, time, and… suffering, compared to the free alternative sitting in your bathroom.
Let’s run it through the filter.
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The Claims
Walk through any cold plunge brand website or Joe Rogan’s episode and you will encounter some version of the following:
● Boosts testosterone significantly
● Accelerates muscle recovery
● Reduces inflammation
● Improves mood and reduces depression and anxiety
● Enhances focus and mental clarity
● Boosts metabolism and fat burning
● Improves sleep
● Extends longevity
That is a remarkable list. Let’s examine what the evidence actually supports.
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Running It Through The MED Report Filter
Does the evidence clear the bar?
Testosterone — No.
This is the most confidently stated and most poorly supported claim in cold plunge marketing. Three peer-reviewed studies that directly measured testosterone before and after cold water immersion all found either a decrease or a blunting of the normal post-exercise testosterone rise. A 2019 University of Rhode Island study found cold water immersion blunted and delayed the testosterone rise after resistance exercise. A 2025 Polish study in young winter swimmers found a statistically significant drop after a single immersion below 4°C. The 2025 University of South Australia meta-analysis of 11 studies and 3,177 participants did not even list testosterone as a primary or secondary outcome, because the evidence base is not there.
Cold plunges do not raise testosterone. The evidence suggests they may temporarily lower it.
Muscle Recovery — Partially, with a significant catch.
For elite athletes doing high-volume training, cold water immersion does show modest benefits for short-term muscle soreness reduction and recovery between sessions. This is probably the strongest evidence base in the cold plunge literature. However, here is the catch your biohacking influencer never mentions: a growing body of evidence suggests that regular cold water immersion after strength training may blunt muscle adaptation, meaning it may reduce the actual gains you are trying to make. If building strength or muscle is a goal, systematically icing your muscles after every workout may be working against you.
For you, trying to optimize healthspan, not a professional athlete trying to play again tomorrow, this benefit is largely irrelevant.
Inflammation — Mixed and overstated.
Cold water does acutely reduce inflammation markers, but the clinical significance of this for a generally healthy person is unclear. Acute inflammation after exercise is part of the adaptation process. Routinely suppressing it may not be the health optimization move it is marketed as. The evidence here is primarily from athletic populations and does not cleanly translate to the general wellness consumer.
Mood, Depression, and Anxiety — Real, but the cold is not the reason.
This is where it gets genuinely interesting, and genuinely humbling for the cold plunge industry.
In 2024, researchers published the first properly controlled randomized trial specifically designed to test cold showers for depression and anxiety. Eighty-four women with moderate depressive symptoms were split into two groups. The intervention group followed the Wim Hof Method: cold showers combined with specific breathing techniques. The control group took warm showers with slow, rhythmic breathing. After eight weeks, both groups improved by roughly the same amount. Depressive symptoms dropped approximately 24%. Anxiety fell approximately 27%. Stress decreased approximately 20%.
The cold shower group did not outperform the warm shower group on any primary measure.
Read that again. The first properly controlled study of cold showers for depression found that warm showers with controlled breathing worked just as well.
The 2025 University of South Australia systematic review and meta-analysis of 11 studies and 3,177 participants did find improvements in mood, stress, and energy following cold water immersion. However, the authors noted the significant disconnect between the growing popularity of cold water immersion and the limited quality evidence supporting many of the claimed benefits.
There is likely a real psychological benefit from cold exposure, the deliberate discomfort, the breathing practice, the mental discipline. But the evidence suggests the cold itself may not be the active ingredient. The intentional challenge and the breathing may be doing most of the work.
We will probably run the Wim Hof Breathing Method itself (minus the cold) through The MED Report filter in a future edition, because the breathing component may be doing far more of the work than most people realize.
Focus and Mental Clarity — Plausible mechanism, weak human evidence.
Cold exposure does trigger norepinephrine release, which is associated with improved focus and alertness. Huberman cites this accurately. The problem is that the controlled human studies showing meaningful, lasting cognitive improvements from cold water immersion specifically are limited. Most of the cognitive benefit evidence comes from animal models or small, uncontrolled human studies. The 2025 meta-analysis did not find strong evidence for cognitive improvements.
Metabolism and Fat Loss — Technically real, practically meaningless.
Cold exposure does activate brown adipose tissue and slightly elevates metabolic rate. The effect size is real. The magnitude is trivial for a 40 to 70 year old trying to manage body composition. We are talking about burning an additional 50 to 100 calories in the hours following a cold plunge, an effect that can be achieved by taking a brisk 10-minute walk. The ROI on buying a $5,000 tub to marginally boost metabolism does not survive contact with the MED Report filter.
Sleep — Insufficient evidence.
There is limited quality evidence on cold plunge and sleep specifically. Some anecdotal reports suggest improved sleep quality, but the controlled human data is not there yet.
Longevity — No direct evidence.
There are no long-term randomized controlled trials linking cold water immersion to extended lifespan or healthspan in humans. None. The longevity claims are extrapolated from mechanistic hypotheses, not clinical outcome data. At the MED Report, we do not count extrapolation as evidence.
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Is it worth acting on — at $3,000 to $15,000?
This is the ROI question, and it is where the MED Report filter does its most important work.
The cold plunge industry generated $870 million in 2025. It is projected to reach $1.9 billion by 2035. That is a lot of money flowing toward an intervention whose evidence base, when examined through a clinical evidence lens, supports a narrow set of modest benefits — most of which can be replicated for free.
Here is what a cold plunge delivers that has real, if modest, evidence:
● Some reduction in acute muscle soreness after intense exercise
● A mood and energy boost, likely driven as much by breathing and intentional discomfort as by the cold itself
● A brief increase in alertness and norepinephrine
Here is what delivers the same benefits for free:
● A 30 to 60 second cold shower at the end of your regular shower
● Controlled breathing during that cold shower
The 2024 controlled trial demonstrated this directly. Warm water plus intentional breathing produced the same mood and anxiety improvements as the full Wim Hof cold shower protocol. Your shower does not care whether it costs $15,000 or nothing.
The one population where this calculus changes is elite athletes with high training volumes doing twice-daily sessions who need to recover quickly for the next session. That is most likely not you.
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The Deeper Point
The cold plunge market is a masterclass in how wellness culture monetizes real but narrow evidence.
There is a kernel of legitimate science here, cold water does trigger physiological responses that have real effects. That kernel has been extrapolated, marketed, and amplified into a $870 million industry selling tubs that cost more than most people’s monthly mortgage payments.
The influencers are not lying exactly. But they are optimizing for the 0.1% case, the elite athlete, the extreme biohacker, the person for whom every marginal gain matters, and presenting those benefits as universal.
Your 40 to 70 year old body does not need a $5,000 tub. It needs a functioning shower, thirty seconds of cold water, and deep breathing.
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The MED Report Verdict
💩 NOISE — for the vast majority of us
The evidence for cold plunge therapy as practiced by the general wellness consumer does not justify the cost, space, maintenance, complexity, or suffering of a dedicated cold plunge tub. The benefits that do exist are real but narrow, modest in magnitude, and largely replicable for free.
One important exception: If you are an elite athlete doing high-frequency intense training and need to optimize recovery between sessions, cold water immersion has a legitimate, evidence-supported role. That is not most of us.
The minimum effective action this week:
If you are curious about cold exposure, finish your next shower with 30 seconds of cold water. Breathe deeply and intentionally during it. Notice the effect on your mood and alertness in the next hour. That is the actual intervention the evidence supports. It costs nothing and takes thirty seconds.
Do not buy the tub.
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Sources:
1. PLOS One (2025) — Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis (University of South Australia, 3,177 participants) https://pmc.ncbi.nlm.nih.gov/articles/PMC11778651/
2. Blades et al. (2024) — Randomized controlled trial of cold shower intervention for depression and anxiety https://www.psychiatrypodcast.com/psychiatry-psychotherapy-podcast/episode-232-cold-exposure-for-mental-health-benefits
3. Earp et al. (2019) — Cold-water immersion blunts and delays increases in circulating testosterone and cytokines post-resistance exercise https://pubmed.ncbi.nlm.nih.gov/
4. IceBathLab — Cold Plunge Testosterone Review: Summary of evidence (2025) https://icebathlab.au/do-cold-plunges-increase-testosterone/
5. Grand View Research — Cold Plunge Tub Market Size Report (2025) https://www.grandviewresearch.com/industry-analysis/cold-plunge-tub-market-report
6. Kox et al. (2014) — Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans https://www.pnas.org/doi/10.1073/pnas.1322174111
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