Welcome back to the Fitness Edda. I’m Erik Castiglione, owner and head coach of Viking Athletics, and this week we’re doing something a little different: instead of teaching one concept in depth, we’re putting four of the internet’s most popular wellness trends on trial.
Cold plunging. Intermittent fasting. Fasted cardio. Mouth taping. You’ve seen all four all over your feed, usually pitched by someone with a huge following and total confidence. The problem isn’t that these practices are useless — most of them genuinely do something. The problem is that the claims get stretched way past what the research actually shows. An effect gets discovered in an extreme, tightly controlled scenario, and three re-shares later it’s being sold to you as an everyday miracle.
So for each trend below: what’s the claim, is it true, where did it come from if it’s not, and how should you actually use it (if at all)? Watch the video or read the article below it!
Chapters:
00:00 Introduction
01:05 Cold Plunge / Contrast Therapy
13:14 Intermittent Fasting
20:22 Fasted Cardio
25:58 Mouth Taping
31:44 Conclusion
Do Cold Plunges Actually Boost Dopamine and Cut Inflammation?
Cold plunging is everywhere right now — Ice Barrel, The Plunge, Ice Pod, and a roster of celebrity endorsers from Joe Rogan to Kelly Starrett to Guy Fieri. I do it myself most mornings. But “everybody’s doing it” isn’t the same as “it does what people say it does,” so here’s the claim-by-claim breakdown.
Increased dopamine — true. This claim was popularized by neuroscientist Dr. Andrew Huberman, and it holds up: cold exposure produces a measurable spike in dopamine that, unlike the crash you get from sugar, alcohol, or other quick-hit dopamine sources, stays elevated for several hours afterward.
Decreased inflammation — true, but only one kind. This is where most cold-plunge marketing gets sloppy. There are two very different things called “inflammation.” Acute inflammation is the short-term, localized response to a hard training session — the soreness and swelling that shows up after a workout. Systemic inflammation is chronic, driven by poor lifestyle habits and stress, and it’s a completely different physiological process. Cold plunging reduces acute inflammation. It does nothing to address systemic inflammation, and conflating the two is how a lot of misleading claims get made.
Improved recovery — true, especially paired with heat. Anything that isn’t processed through your bloodstream gets cleared through your lymphatic system, and unlike your circulatory system, the lymphatic system has no pump — it relies on movement to circulate. Cold plunging, especially alternated with a hot shower or sauna, helps move that waste out faster.
Muscle growth — no effect either way, with one exception. Acute inflammation is part of how your body builds muscle, which raised a real concern: does icing your body down block your own recovery process? A meta-analysis (a study that pools the results of every available study on a topic to find the overall trend, rather than relying on any single result) found no difference between full-body cold plunging and doing nothing at all when it comes to muscle growth. The exception: submerging a single limb — like an ankle in a whirlpool bath — does appear to blunt the muscle-building response in that limb. Full-body plunges don’t carry that risk.
Fat burning — technically true, wildly overstated. This is the trend’s biggest exaggeration. Yes, shivering activates brown fat and can convert some white fat cells into more metabolically active brown fat cells. But the study behind this claim put subjects in their underwear in a meat locker for 45 minutes to an hour until they were shivering uncontrollably and their core temperature dropped. Three minutes in a 55-degree plunge tub doesn’t come close to replicating that. When cold plunging was compared to a non-plunging control group with diet and exercise held equal, there was zero difference in fat loss.
The verdict: you get real benefits from cold plunging — dopamine, acute recovery, reduced acute inflammation — and you get them anywhere under 60 degrees. You don’t need a 37-degree tub unless you’re chasing the mental toughness challenge for its own sake. I plunge around 50–55 degrees most mornings and notice better mental clarity and (anecdotally) more resilience to cold weather in general.
Does Intermittent Fasting Burn More Fat Than Any Other Diet?
Intermittent fasting cycles you between an eating window and a fasting window — 16:8, 20:4, alternate-day “Eat Stop Eat,” and similar protocols are the most common versions. If you sleep eight hours a night without a midnight snack, you’re already practicing a mild version of it every day; that’s why breakfast is called “breakfast.”
Improved fat burning — true, but not for the reason people think. Fasting itself doesn’t burn more fat than eating on a normal schedule. What actually happens is that constraining your eating window usually leads you to eat fewer total calories, which puts you in a caloric deficit — and a caloric deficit is what drives fat loss, regardless of when you eat. One of our nutrition coaching clients recently dropped 9 pounds and roughly 2% body fat in six weeks while losing only a tenth of a pound of muscle — not through intermittent fasting specifically, but through a caloric deficit, high protein, and consistent strength training. When calories and protein intake are held equal, intermittent fasting produces the same fat-loss results as any other dietary approach, including low-carb, low-fat, or keto.
Reduced inflammation — true, but it’s the deficit doing the work again. Chronic inflammation is tied closely to your gut microbiome and to consistently eating in a caloric surplus with heavily processed foods. Intermittent fasting tends to reduce total intake, which reduces that inflammatory driver — but it’s the deficit causing the effect, not the fasting window itself.
Improved growth hormone production — true, but irrelevant if you strength train. Intermittent fasting does slightly boost HGH compared to baseline. But people who strength train and eat normally see the same benefit. If you’re not strength training, fasting might nudge your HGH up — but HGH’s main job is supporting size and strength, so without training to use it, the benefit is moot.
Autophagy — true, but at a dose you’re not hitting. Autophagy is your body’s cellular self-repair process, and it’s the most overstated claim in the intermittent fasting world. The research showing meaningfully improved autophagy comes from medically controlled 72-hour fasts with IV feeding and monitoring. A 16-hour overnight fast does not get you there. This is the same pattern we saw with cold plunging and brown fat: an effect that’s real at an extreme dose gets marketed as if it applies to a much milder, everyday practice.
The verdict: intermittent fasting is a legitimate tool for people who find a controlled eating window easier to stick to than counting every meal. But the honest name for what’s actually happening is “a controlled feeding window that tends to produce a caloric deficit” — not a metabolic hack that outperforms every other diet.
Does Fasted Cardio Burn More Fat Than Eating Beforehand?
Fasted cardio means training — usually first thing in the morning — before eating anything. The theory: with your glycogen stores depleted, your body has no choice but to burn fat as fuel, making you more “fat-adapted.”
That part is accurate: training in a fasted state does improve your body’s ability to use fat as fuel. The catch is that it improves fat utilization at the expense of your ability to use glucose efficiently — and glucose is the fuel your muscles need for high-intensity work and the fuel your brain runs on for cognitive function. Being “metabolically flexible” means your body can use both fuel sources well, not that it’s maxed out on one.
As for burning more stored body fat — that still only happens in a caloric deficit, same as with intermittent fasting. Whether the dietary fat you eat gets burned immediately or stored and used later evens out over a full day. More recent research actually shows the opposite of what fasted-cardio advocates claim: people training fasted tend to push less hard, burn fewer calories during the session, and their bodies compensate afterward by conserving energy elsewhere throughout the day — because your body’s default setting is to store energy, not needlessly burn through it.
The verdict: if you’re a performance athlete, skip fasted cardio — you want both fuel systems trained, which means training zone 2 for fat efficiency and high-intensity work for glucose efficiency, ideally fed. If you just prefer training on an empty stomach and you’re otherwise in a caloric deficit, it won’t hurt you — but it isn’t the fat-loss shortcut it’s marketed as.
Does Mouth Taping Stop Snoring and Improve Sleep?
Mouth taping — literally taping your mouth shut overnight to force nasal breathing — picked up momentum after Kelly Starrett featured it in Built to Move. The claims: it prevents snoring, helps with sleep apnea, improves REM sleep, and strengthens diaphragmatic breathing.
Prevents snoring — false. Snoring is caused by the weight of your neck and throat tissue collapsing against your airway, usually worse when sleeping on your back. Mouth taping doesn’t change that mechanism at all — side sleeping is a far more effective fix.
Cures sleep apnea — false, and possibly counterproductive. Sleep apnea happens when the weight of your chest overwhelms your diaphragm and breathing repeatedly stops. The standard treatment, a CPAP machine, works by maximizing oxygen intake — through whatever airway is available, mouth included. Taping your mouth shut restricts one of your two intake pathways, which cuts against the entire goal of getting more oxygen in.
Improves REM sleep — false. You cycle through roughly 90-minute sleep stages all night, and REM — the stage where your brain processes and sorts information — is a small portion of each cycle that you can only reach after passing through non-REM sleep, which is oxygen-intensive recovery time for your body. Restrict your oxygen intake by taping your mouth, and you make it harder to get through non-REM sleep cleanly in the first place, let alone improve REM.
Improves diaphragmatic breathing — true, just not while you’re asleep. Forcing nasal breathing does train your diaphragm. But overnight is the worst time to practice it, since restricting airflow while you sleep works against your body’s need for maximum oxygen. If you want the diaphragmatic benefit, use it during zone 2 cardio (taping your mouth is actually a reliable way to keep yourself in the right heart rate zone) or during quiet moments at your desk when you’re not talking or on a call.
The verdict: if you snore, sleep on your side. If you suspect sleep apnea, see a doctor — don’t self-treat with tape. Nasal strips, which physically open your nasal passage rather than restricting your mouth, are the better tool if you’re trying to maximize airflow overnight.
The Bottom Line
Here’s the pattern across all four trends: in almost every case, the underlying science is real — it’s just been measured at an extreme dose (a 72-hour medical fast, a near-hypothermic cold exposure, a single-limb ice bath) and then marketed as if it applies to a much smaller, everyday version of the practice. That’s not the same as the claim being a lie. It just means dosage, context, and the actual mechanism matter more than the headline.
| Trend | What’s actually true |
|---|---|
| Cold plunging | Boosts dopamine and aids acute recovery; doesn’t burn meaningful fat or block muscle growth (full-body) |
| Intermittent fasting | Works for fat loss because it creates a calorie deficit, not because of the fasting itself |
| Fasted cardio | Improves fat-burning capacity at the cost of glucose efficiency; no fat-loss edge without a deficit |
| Mouth taping | Trains diaphragmatic breathing while awake; does nothing for snoring, apnea, or REM sleep overnight |
None of these trends are worthless, and none of them are the miracle they’re sold as. Used with the right context, most of them earn a place in a well-built health routine. Used blindly because a podcast guest said so, they’re just noise.
Always consider the source. Andrew Huberman is a neuroscientist, so his dopamine claim about cold exposure is squarely in his lane. Even smart, credible people wander outside their expertise sometimes — so stay a little skeptical, question the claim, and check what the actual study measured before you build a routine around it.
If you want help sorting real evidence-based programming from wellness-trend noise, reach out to Coach Erik at Viking Athletics in West Hartford, CT.
FAQ: Wellness Trends, Quickly
Does cold plunging burn fat? No, not meaningfully. Cold plunging only triggers real fat-burning through shivering after prolonged exposure to near-hypothermic temperatures — far beyond a typical 2–3 minute plunge session.
Is intermittent fasting better than other diets for weight loss? No. When calories and protein intake are equal, intermittent fasting produces the same fat-loss results as any other diet. Its main advantage is adherence — some people find a set eating window easier to stick to.
Does fasted cardio burn more fat than eating before a workout? No. Fat loss depends on being in a caloric deficit, not on the timing of your last meal. Fasted training does improve your body’s ability to use fat as fuel, but at some cost to glucose efficiency for high-intensity work.
Does mouth taping stop snoring or help sleep apnea? No. Snoring is caused by airway tissue collapsing under the weight of the neck, and sleep apnea requires medical treatment such as a CPAP machine. Mouth taping restricts airflow rather than improving it.
Is cold plunging safe to do daily? For most healthy adults, yes — anywhere under 60 degrees for a few minutes delivers the researched benefits (dopamine, acute recovery) without needing extreme cold. Anyone with a cardiovascular condition should check with a doctor first.