By Rob Stickler — Plunge Performance & Recovery, Dana Point, CA

Over the past year or so, we started noticing something at our studio in Dana Point. A quiet buzz among our female clients — conversations in the lobby, questions at the front desk, a general hesitation that hadn’t been there before. Gradually, the ratio shifted. Fewer women booking cold plunge sessions relative to men. Not a dramatic drop, but a clear trend — and one we weren’t the only facility noticing.

The common thread? A podcast. Specifically, a series of podcast appearances by exercise physiologist Dr. Stacy Sims, whose message about women and cold exposure had clearly made the rounds.

The Podcast Appearances That Shifted the Conversation

Dr. Stacy Sims, PhD — an exercise physiologist, nutrition scientist, and author of the bestselling book ROAR — appeared on a string of massively popular podcasts in 2024 and 2025: Huberman Lab (July 2024), Diary of a CEO, and most recently The Mel Robbins Podcast (March 2025). The Mel Robbins clip alone racked up over 111,000 likes on TikTok.

Her core message across these appearances was consistent: women are not small men, fitness and nutrition research has historically been built on male physiology, and women need protocols designed for their unique biology.

That part? Absolutely valid. And frankly, overdue.

But nestled inside that important message was a claim that gained enormous traction — and it’s the one that’s been quietly discouraging women from cold plunge therapy across the country:

“It’s too cold for women.”

Sims argued that traditional ice bath temperatures (typically 38–45°F) cause such severe vasoconstriction in women that the body essentially shuts down rather than adapting. She recommended women use water around 55–60°F (15–16°C) instead, and stated that heat — not cold — produces better metabolic adaptations for women. She also raised concerns about cortisol spikes and the stress response cold exposure places on the female body.

These are legitimate scientific talking points. But what happened next wasn’t a nuanced conversation about temperature protocols. What happened was that millions of women heard a simple, sticky takeaway: cold plunging is bad for me. I should stop.

And many of them did.

What Dr. Sims Actually Said (vs. What People Heard)

This is worth unpacking, because Sims herself has since clarified her position. In a 2025 interview, she stated plainly: “I didn’t say women shouldn’t cold plunge. I said the science shows warmer temperatures are better for women.”

Here’s a breakdown of her actual claims and how they got distorted in the cultural echo chamber:

Claim 1: Cold water causes too much vasoconstriction in women, leading to a “shutdown” response.

Sims referenced research showing women vasoconstrict faster and begin shivering at higher temperatures than men. She suggested this means extremely cold water overwhelms the female nervous system rather than triggering beneficial adaptation.

Claim 2: Women get the dopamine and metabolic benefits at warmer temperatures (around 55–60°F).

Rather than arguing against cold exposure entirely, Sims proposed that women don’t need to go as cold as men to unlock the same neurochemical benefits — norepinephrine release, mood elevation, and metabolic activation.

Claim 3: Heat is better for women than cold.

Sims advocated for sauna use over cold plunging for women, citing stronger serotonin signaling, cardiovascular benefits, and better hormonal adaptation to heat stress.

Claim 4: Cold exposure spikes cortisol, which is especially problematic for women already under chronic stress.

This is the claim that scared people the most. The implication was that cold plunging could disrupt hormonal balance, impair sleep, blunt thyroid function, and even contribute to fat storage — particularly for women in perimenopause and menopause.

The Experts Who Pushed Back

Here’s where the story gets interesting. Because while Sims’ podcast appearances went viral, a growing chorus of researchers and practitioners with deep expertise specifically in cold exposure pushed back — hard.

Dr. Thomas Seager, PhD — Morozko Forge

Dr. Thomas Seager is an Associate Professor at Arizona State University and co-founder of Morozko Forge, one of the most well-known ice bath companies in the world. In March 2025, he published a detailed, research-cited rebuttal titled “Ice Bath Benefits Women” — and followed it with a YouTube video directly addressing Sims’ claims.

Seager’s core arguments:

On the “women are more cold-sensitive” claim: Seager acknowledges the data showing women begin shivering at higher temperatures. But he points out three critical problems with Sims’ conclusion. First, population-level averages don’t predict individual responses — the data showed massive overlap between men and women, with several women in the studies being more cold-tolerant than several of the men. Second, the difference may be about experience, not inherent biology — men in the studies were more likely to have prior cold exposure from outdoor work and winter sports. And third, a study of Finnish women showed that just one prior cold exposure significantly improved tolerance during a second session.

On cortisol: Seager argues that the cortisol concern is overblown and misunderstands the nature of acute vs. chronic stress. A brief cortisol spike from a 2–3 minute cold plunge is a hormetic stressor — the same category as exercise, fasting, or sauna use. The body adapts. The stress response becomes more efficient. Baseline cortisol actually decreases over time with regular practice.

On the real-world evidence: Seager cites a University of Portsmouth survey of over 1,000 British women engaged in cold water swimming. The findings directly contradicted Sims’ temperature recommendations: 60% of respondents said they believe colder water temperatures result in greater benefits. Women reported improved mood, less irritability, and less pain.

On what Sims left out: Perhaps most damningly, Seager points out that Sims’ podcast appearances failed to summarize the many documented benefits of cold plunge for women — leaving viewers with a one-sided impression. He also notes that Sims has never published a study on cold plunge therapy, and that her podcast commentary conflicts with female scientists who have superior expertise in this specific domain.

Among those scientists: Dr. Lauren Burns, PhD, Olympic gold medalist in Taekwondo and researcher in female sports performance, whose published work found that the highest-achieving female athletes ice bath more often than their less-accomplished peers.

Dr. Susanna Søeberg, PhD — The Søeberg Institute

Dr. Susanna Søeberg is the metabolic scientist whose research at the University of Copenhagen gave us the globally recognized Søeberg Principle — the protocol, endorsed by Andrew Huberman, that recommends ending with cold (not heat) to maximize metabolic benefits.

In April 2025 — weeks after the Mel Robbins episode aired — Søeberg issued what amounted to a press release rebuttal, published through the Søeberg Institute:

“Women are not too sensitive for cold plunging. What women need is nuanced guidance on how to use cold therapy effectively and safely.”

“The science does not support the idea that women should stay out of cold water. It supports the idea that we need to understand physiology and context.”

On the cortisol question specifically, Søeberg was unequivocal: the initial cortisol spike during cold immersion is temporary and primarily linked to anticipation and nervousness rather than the cold itself. After the first few sessions, the cortisol response fades entirely. With regular practice, baseline cortisol levels actually decrease over time — helping regulate overall stress.

Once that initial shock passes, Søeberg explains, the body activates the diver’s response — a powerful parasympathetic reflex. The brain then releases a cascade of dopamine, oxytocin, and noradrenaline. These neurochemicals lower inflammation, boost immunity, improve heart health, and activate brown fat for better metabolism.

Rather than telling women to avoid cold, Søeberg offered a practical, cycle-aware protocol:

• Follicular phase (first half of cycle): Cold plunge for 1–4 minutes
• Luteal phase (second half): Reduce to 1–2 minutes, or substitute a cold shower
• Temperature: 15°C (59°F) provides the full suite of health benefits — it doesn’t need to be colder, but acclimatized women who enjoy colder water can absolutely go there
• The key: Intelligent application, not fear-based avoidance

Gary Brecka — Human Biologist & Biohacker

Gary Brecka, a human biologist and one of the most visible advocates for cold plunge therapy, has consistently championed cold exposure for everyone — men and women alike. While his commentary hasn’t been a direct point-by-point rebuttal of Sims, his extensive public content reinforces the mechanisms that Sims’ messaging undermined.

Brecka emphasizes that cold water immersion triggers a 250% increase in dopamine — a neurochemical response that is not sex-specific. The dopamine elevation persists for hours, providing sustained mood improvement, mental clarity, and reduced anxiety. He also highlights brown fat activation as one of the most powerful metabolic tools available, noting that women actually tend to have more brown fat than men — meaning they may be even better positioned to benefit from cold exposure.

What the Research Actually Shows: Six Benefits for Women

Setting aside the podcast drama, here’s what the published literature says about cold plunge therapy and female physiology:

1. Thyroid Function. Multiple case studies document women resolving thyroid disorders after adopting a cold plunge practice. Cold modulates thyroid function by recruiting brown adipose tissue, which works in feedback with the thyroid. A study of healthy Finnish women showed no thyroid abnormalities from a twelve-week program of whole-body cryotherapy — meaning cold normalizes thyroid function rather than disrupting it.
2. Metabolism & Insulin Sensitivity. A study of fourteen Polish women who undertook regular winter swimming confirmed improvements in insulin sensitivity and decreases in leptin and insulin levels. Women may actually have an advantage here — research shows women possess more brown fat than men, and that brown fat becomes more active in cooler conditions.
3. Menstruation, Menopause & Endometriosis. The University of Portsmouth survey of over 1,000 women cold water swimmers found improved mood, less irritability, and less pain associated with menstrual and perimenopausal symptoms. And Sims herself has acknowledged promising early results from a clinical trial at the University of Adelaide using cold therapy for endometriosis.
4. Mental Health. A landmark case study from the University of Portsmouth documented a young woman with treatment-resistant major depression whose condition was rescued by a regular cold water swimming program. A separate clinical trial at Bournemouth University measured not just self-reported mood improvements, but actual changes in brain function via fMRI — enhanced activity in areas governing attention, emotion, and self-regulation.
5. Bone Metabolism. Two studies from a Chinese research group measured improved blood markers of bone metabolism following deliberate cold exposure — suggesting that the metabolic stimulation from cold plunging may extend to bone health in ways that reduce osteoporosis risk.
6. Recovery from Exercise. A 2024 randomized controlled trial studied cold water immersion in women specifically — participants submerged in 57°F water for 15 minutes following exercise-induced muscle damage. The cold plunge group reported lower levels of muscle soreness than the control group. Notably, Sims herself has acknowledged that women vasodilate after exercise (blood flows to the periphery), and that cold immersion helps redirect blood centrally to aid recovery — a benefit she says is actually stronger for women than men.

So What Actually Happened?

Here’s the uncomfortable truth: a nuanced scientific position got flattened into a viral soundbite.

Stacy Sims’ actual position — that women may benefit from slightly warmer cold exposure temperatures and should consider their menstrual cycle phase — is reasonable and worth discussing. But that’s not what 111,000 TikTok viewers took away from a 60-second clip. What they heard was: cold plunging is bad for women. The science says so. Stop doing it.

And that message was amplified by the enormous reach of Mel Robbins, Huberman, and Diary of a CEO — platforms with a combined audience of tens of millions — without adequate counterpoint from researchers who specialize in cold exposure.

The result? Women who were enjoying cold plunging — who felt better, slept better, managed their stress better — got scared and quit.

We’ve seen it at our studio — that gradual shift in who’s walking through the door. And conversations with other cold plunge facilities suggest we’re not alone.

Our Take at Plunge Performance & Recovery

We’re not here to tell Dr. Sims she’s wrong about everything. Some of her points are valid — particularly around adjusting protocols for menstrual cycle phase and avoiding extreme cold immediately after heavy strength training.

But we are here to say this: cold plunging is not bad for women. Full stop.

The cortisol argument collapses under the weight of the actual research. The temperature argument is far more nuanced than the soundbites suggest. And the benefits — from mood and metabolism to menstrual symptom relief and mental health — are well-documented and, in many cases, especially relevant to women.

Here’s what we recommend for women at our studio:

1. Start at 45–50°F with expert guidance on your first plunge. Our staff walks you through breathing, timing, and exit technique so you unlock the full dopamine and norepinephrine response without overwhelming your nervous system.
2. Work your way colder as you acclimate. Your body adapts. That’s the entire point.
3. Be cycle-aware, not cycle-afraid. Follicular phase? Go for it. Luteal phase? Shorter duration, or a cold shower.
4. Don’t plunge immediately after heavy lifting if muscle growth is your primary goal. But before cardio, or on a recovery day? Absolutely.
5. Listen to YOUR body, not a podcast clip. If cold plunging makes you feel amazing — it’s working. Your lived experience is data too.

The science is on your side. The researchers who actually study cold exposure are on your side. And we’re on your side.

Come plunge.

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Medical disclaimer: Always check with your doctor or qualified practitioner before starting a cold plunge practice. Cold immersion isn’t appropriate for everyone — particularly anyone with heart conditions, uncontrolled high blood pressure, Raynaud’s, pregnancy complications, or other medical concerns. Our staff can guide you on-site, but personalized medical advice always comes first.

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Plunge Performance & Recovery is located at 34098 E Pacific Coast Hwy, Dana Point, CA. We offer cold plunge therapy, traditional sauna, red light therapy, PEMF, compression therapy, and more. Book your first session at plungeperformance.com.

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Sources & Further Reading

• Morozko Forge: “Ice Bath Benefits Women” — Dr. Thomas Seager, PhD (March 2025)
• Søeberg Institute: “Dr. Susanna Søeberg Sets the Record Straight: Women and Cold Plunging” (April 2025)
• Morozko Forge YouTube: “Dr Stacy Sims Rebuttal: Should Women Cold Plunge?” (April 2025)
• Burns et al. (2022): Survey of elite female athletes’ recovery behaviors, BMC Sports Science
• Pound et al. (2024): Women’s perceptions of cold water swimming effects on menstrual/perimenopausal symptoms, Post Reproductive Health
• Yankouskaya et al. (2023): Cold water immersion and brain network interactions, Biology
• Van Tulleken et al. (2018): Open water swimming as treatment for major depression, Case Reports
• Gibas-Dorna et al. (2016): Winter swimming and insulin sensitivity in women, Scandinavian Journal of Clinical & Laboratory Investigation
• Smolander et al. (2009): Whole-body cryotherapy and thyroid function in healthy women, Cryobiology
• Søeberg Principle: End with cold to maximize metabolic benefits (Huberman Lab, 2023)