Can Infrared Saunas Help With Weight Loss?
It is one of the most searched questions in the sauna world: can an infrared sauna help you lose weight? You have probably seen bold claims about “melting fat” and “burning hundreds of calories per session.”
At Elysian Solara, we would rather give you the truth than a sales pitch — even when the honest answer is less flattering to a product we sell. So let us separate the myth from the mechanism.
The Honest Short Answer
No — not in any direct or meaningful way. An infrared sauna does not burn away body fat. The dramatic drop you might see on the scales straight after a session is almost entirely water weight from sweating, and you regain it the moment you rehydrate.
There are some plausible indirect ways a sauna might support a weight-management routine, and we cover them below. But we want to be upfront: those pathways are proposed and largely untested. No study has shown that adding an infrared sauna to your week changes body fat or body weight. If that is what you are buying a sauna for, buy it for something else.
Why the Scales Drop After a Session
During a session you sweat, sometimes heavily. That fluid loss can register as several hundred grams or more on the scales. It looks like rapid weight loss, but it is not fat — it is water your body needs back. As soon as you drink to rehydrate (which you should), that weight returns.
This is exactly why “lose weight in the sauna” claims are misleading. Chasing water-weight numbers is not weight loss; it can also leave you dehydrated, which is the opposite of healthy.
Does a Sauna Burn Calories?
Some, but nobody can honestly tell you how much. When you heat up, your heart rate rises and your body works to cool itself, and that uses energy. What does not exist is a measurement: we could not find any study that has directly measured the energy a person expends during a sauna session using proper calorimetry.
That matters, because the specific numbers you see quoted online — “300 calories a session”, “as much as a 30-minute run” — are not drawn from any such measurement. They are estimates repeated between websites until they sound like facts. We have deliberately removed figures like that from this article rather than pass them on. Treat sauna energy expenditure as real but unquantified, and certainly not something to plan a diet around.
What the Metabolic Research Actually Shows
If heat were going to help with body composition, you would expect to see it in the muscle and metabolic markers that exercise moves. Researchers have looked, and the results are sobering.
In a six-week study, twenty young sedentary men were assigned to either passive heat therapy (40–50 minutes at 40 °C in a heat chamber, three times a week) or time-matched moderate-intensity cycling. Both improved aerobic capacity and whole-body insulin sensitivity, but the heat group improved insulin sensitivity by 15% against 36% for cycling. More tellingly, heat did not increase the muscle machinery that cycling did: GLUT4, the glucose transporter, rose 14% with cycling but was unchanged with heat (7%, p = 0.217), as were mitochondrial density (11%, p = 0.443) and intramuscular triglyceride content (1%, p = 0.957) (Hesketh et al., 2019). This was a heat chamber rather than a sauna, and infrared specifically was not tested, so read it as a direction of travel rather than a verdict — but the direction is clear. Heat is not a substitute for training.
The Possible Ways a Sauna Might Support Weight Goals
Here is where a sauna may earn a place — not by burning fat, but by supporting the lifestyle that does. Each of these is a reasonable idea with thin evidence behind it, so we have flagged what is actually known.
Recovery and consistent training — genuinely mixed evidence
The theory is that if heat helps you feel ready to train again, you train more consistently, and consistency over months is one of the biggest drivers of real body composition change. The evidence for the first step in that chain is weaker than you might expect, and it cuts both ways.
In favour: in a trial of twenty trained middle-distance runners, three weeks of post-exercise sauna bathing improved heat tolerance and markers of exercise capacity, including maximal aerobic capacity and speed at a fixed blood-lactate concentration, compared with training alone (Kirby et al., 2021). Separately, in seven well-trained male cyclists, post-training sauna expanded plasma volume by around 18% after just four exposures (Stanley et al., 2015) — though in that same study heart-rate recovery moved unfavourably, the heart-rate variability changes were trivial, and the authors concluded that the performance benefits of post-training sauna remain to be clarified.
Against: a study of twenty-seven recreationally active men found that a traditional sauna bath taken after exercise did not further change the hormonal responses already produced by the exercise itself — and that a sauna bath on its own was strenuous enough to leave maximal leg-press force still reduced 24 hours later. The authors concluded that traditional sauna bathing may not be advisable in the 24 hours before your next training session (Rissanen et al., 2020).
Two things to hold onto. First, all three of those studies used traditional sauna, not infrared, and findings do not automatically transfer between the two. Second, none of them measured body weight, body fat, or training adherence. The link from "feels better" to "loses weight" is an assumption, not a finding.
Comfort and stiffness — outside a training context
The clearest infrared-specific evidence is not about athletes at all. In a pilot study, thirty-four patients with rheumatoid arthritis or ankylosing spondylitis had eight infrared sauna treatments over four weeks. Pain and stiffness decreased significantly during sessions, and the treatment was well tolerated with no adverse effects, though the improvements across the four-week period did not reach statistical significance (Oosterveld et al., 2009). It was small, uncontrolled and conducted in people with inflammatory rheumatic disease — so it tells us infrared heat is comfortable and well tolerated, not that it aids recovery from training or supports weight loss.
Sleep — plausible, unproven
Poor sleep is consistently associated with weight gain, stronger cravings and disrupted appetite hormones. Many people find an evening sauna session relaxing and helpful for winding down. We would call that a plausible supporting habit and nothing more: direct evidence on sauna and sleep quality is limited, and we are not aware of research connecting sauna, sleep and body weight in a single chain.
Stress and appetite — the most overclaimed link
You will often read that saunas lower cortisol and therefore curb stress eating. We want to correct that, because we have made a version of that claim ourselves in the past.
The source usually cited is a 2021 mechanistic review that proposes sauna bathing as a preventive strategy for people in high-stress occupations such as firefighters, police and first responders (Henderson et al., 2021). It is a review of possible mechanisms, not a study of those workers, and it does not report that sauna lowers cortisol. Its cortisol passages describe what chronic stress does to the body, and it notes that hormonal markers respond variably to acute heat and that the data are scarce. Infrared-specific stress-hormone data is thinner still. If a sauna session helps you feel calmer, that is a real and worthwhile thing — we just cannot tell you it is lowering your cortisol or steadying your appetite.
A keystone habit
People who build a regular sauna ritual often find it anchors a wider set of healthy behaviours — hydration, movement, winding down properly. This is an observation about habit-building rather than a research finding, but that ripple effect can matter more than any single session.
What a Sauna Will Not Do
To be clear: a sauna will not replace a balanced diet or regular exercise, it will not “spot-reduce” fat from a particular area, and it will not melt fat off your body. Anyone promising those outcomes is selling hype. Sustainable weight change still comes from the fundamentals — nutrition, movement, sleep and consistency — and a sauna is a pleasant, supportive part of that picture rather than a driver of it.
How to Use a Sauna as Part of a Healthy Plan
Use it for what it is good at: a comfortable, low-risk way to wind down and enjoy heat. Hydrate thoroughly before and after every session to replace the fluid you lose. Given the findings above, it is worth being thoughtful about timing a long, hot session immediately before a hard training day. And never use heat as a way to “sweat off” weight before an event — it is both ineffective and unsafe.
Safety
Dehydration is the main risk to watch. Drink plenty of water, keep sessions moderate, and speak with your doctor before using a sauna if you are pregnant, have a heart condition, low blood pressure, or any medical concern. Stop if you feel dizzy or unwell. If you are managing your weight for a medical reason, that is a conversation for your GP, not a sauna.
The Elysian Solara Take
If you want a device that burns fat, a sauna is not it, and we will never pretend otherwise. What an infrared sauna reliably offers is comfortable, well-tolerated heat and a ritual people genuinely look forward to. Whether that indirectly supports your weight goals is an open question the research has not answered. Buy one because you will use it and enjoy it — not because of a number on the scales.
FAQ: Saunas and Weight Loss
Do you lose weight in an infrared sauna?
Only water weight, which returns when you rehydrate. A sauna does not directly burn meaningful body fat.
How many calories does a sauna burn?
Nobody can say with confidence. We could not find a study that has directly measured energy expenditure during a sauna session, so any specific calorie figure you see quoted is an estimate rather than a measurement. It is not a number to build a weight-loss plan on.
Can a sauna help me lose weight at all?
Not directly. There are plausible indirect pathways through recovery, sleep and stress, but no study has shown that adding a sauna changes body weight or body fat.
Is infrared better than a traditional sauna for weight loss?
There is no good evidence that either helps with weight loss, so there is nothing meaningful to compare. Most of the sauna research covers traditional saunas, and those findings should not be assumed to apply to infrared.
Is it safe to sauna while dieting?
For most healthy adults, yes, as long as you stay well hydrated. Speak with your doctor if you have any medical concerns.
References
- Kirby NV, Lucas SJE, Armstrong OJ, Weaver SR, Lucas RAI (2021). Intermittent post-exercise sauna bathing improves markers of exercise capacity in hot and temperate conditions in trained middle-distance runners. European Journal of Applied Physiology. PMID: 33211153
- Rissanen JA, Häkkinen A, Laukkanen J, Kraemer WJ, Häkkinen K (2020). Acute neuromuscular and hormonal responses to different exercise loadings followed by a sauna. Journal of Strength and Conditioning Research. PMID: 31490429
- Stanley J, Halliday A, D'Auria S, Buchheit M, Leicht AS (2015). Effect of sauna-based heat acclimation on plasma volume and heart rate variability. European Journal of Applied Physiology. PMID: 25432420
- Oosterveld FG, Rasker JJ, Floors M, Landkroon R, van Rennes B, Zwijnenberg J, van de Laar MA, Koel GJ (2009). Infrared sauna in patients with rheumatoid arthritis and ankylosing spondylitis: a pilot study showing good tolerance, short-term improvement of pain and stiffness, and a trend towards long-term beneficial effects. Clinical Rheumatology. PMID: 18685882
- Hesketh K, Shepherd SO, Strauss JA, Low DA, Cooper RJ, Wagenmakers AJM, Cocks M (2019). Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content. American Journal of Physiology — Heart and Circulatory Physiology. PMID: 31074654
- Henderson KN, Killen LG, O'Neal EK, Waldman HS (2021). The Cardiometabolic Health Benefits of Sauna Exposure in Individuals with High-Stress Occupations. A Mechanistic Review. International Journal of Environmental Research and Public Health. PMID: 33513711
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