Does a sauna help you lose weight? What the scale drop is, and what it is not

“Does a sauna help you lose weight” is three questions. Does the scale go down? Yes, every time. Do you burn many calories? No. Does regular use take off fat? Not in any trial big enough to trust. This page takes each in turn, then the version that can kill you: using heat to make weight. It has no product picks; the saunas pillar has those.

Does a sauna help you lose weight?

Only on the bathroom scale, and only until you drink. Here is where the number you see after a session comes from:

The first row is the one people notice and the one that means least: a litre of sweat weighs about a kilogram, 2.2 lb, and the scale cannot tell water from fat.

Is the weight you lose in a sauna water?

Yes, almost all of it. The largest dataset is Podstawski and colleagues’ 2014 study in The Scientific World Journal: 674 sedentary Polish students aged 19 to 20, weighed nude before and after two 10-minute sessions lying in a sauna at 90°C (194°F) and 35% humidity, with a 30-second 50°F dip between. Mean loss was 0.37 kg for women and 0.50 kg for men. Bigger bodies lost more: overweight and obese men averaged 0.82 kg (1.8 lb), and the largest single loss was 1.3 kg (2.9 lb). The authors’ conclusion was about fluid replacement, not weight control.

The same group’s 2019 study in BioMed Research International, and the one measured sauna blanket session, point the same way:

Both Podstawski protocols sit at or just above the 194°F sensor cap on UL-listed US heaters, explained in the temperature guide, so a normal home round of 10 to 20 minutes at 160 to 190°F will usually take off less.

Sweat is water and salt, nothing else of consequence. The American College of Sports Medicine’s 2007 position stand on fluid replacement (Sawka and colleagues, Medicine & Science in Sports & Exercise) says to estimate sweat loss by weighing before and after, and to replace about 1.5 litres for every kilogram lost, because some of what you drink leaves as urine. Do that and the scale comes back. If it does not, you are still dehydrated, which is not the same as lighter.

Does a sauna burn calories? How many?

A few, and fewer than your heart rate suggests. Our sauna calorie and sweat estimator runs the American College of Sports Medicine’s metabolic equation with the formula printed: for a 175 lb adult sitting 20 minutes at 175°F, 42 to 56 kcal at 1.5 to 2.0 METs. The same 20 minutes on the sofa costs about 28 kcal, so the sauna adds around 14 to 28. A pound of body fat stores roughly 3,500 kcal: at the top of our band, on the order of 125 twenty-minute sessions per pound, on paper, if nothing else changed.

Why does it feel like more? Because the heart is working hard. Ketelhut and Ketelhut (Complementary Therapies in Medicine, 2019) measured 19 healthy adults through 25 minutes at 93°C (199°F) and 13% humidity: blood pressure and heart rate rose steadily, to the levels the same people reached cycling at about 60 to 100 watts. In Podstawski’s 2021 study of 30 active young men doing four 12-minute rounds at 194 to 196°F (International Journal of Environmental Research and Public Health), average heart rate was 102.5 beats per minute and peak 143.

That is a real cardiovascular load, not calories burned at 60 to 100 watts. In the heat the heart pumps blood to the skin to shed heat; your leg muscles are not doing the work they do on a bike, and Ketelhut compared heart rate and blood pressure, not oxygen use. It is also why a watch that estimates calories from heart rate should over-count in a sauna. We have not tested one against a metabolic cart, so treat that as reasoning, not a measurement.

Sauna weight loss: what the longer studies found

Could regular use do more than one session? Four lines of evidence get cited, and none settles it.

• The Japanese sauna-therapy work. A 2003 review by Biro, Masuda, Kihara and Tei (Experimental Biology and Medicine), whose group studied repeated 15-minute sessions in a 60°C (140°F) dry sauna, states that in obese patients body weight and body fat decreased significantly after two weeks of sauna therapy, without a rise in the hunger hormone ghrelin. The abstract gives no numbers, sample size or control group for that finding, so we cannot size it.
• One small controlled trial in athletes. Bartolomé and colleagues (Journal of Thermal Biology, 2021) gave 18 semi-professional footballers nine sessions in a dry sauna at about 100°C (212°F) over three weeks, with 18 controls. The sauna group’s body weight, BMI and body fat fell; the controls did not change. The abstract does not say how much fat or how it was measured, and many body-fat methods are thrown off by hydration. One small study, young athletes in training, at a temperature a US electric sauna cannot reach.
• The trials pooled for metabolic health. Hamaya and colleagues’ 2025 meta-analysis in the American Journal of Preventive Cardiology pooled 20 randomized trials of saunas, hot baths and similar heating, two to 15 weeks long. They found no significant pooled effect on fasting glucose, HbA1c, cholesterol, triglycerides or resting heart rate; a possible fall in systolic blood pressure appeared only with whole-body heating and in people with heart risk. Body weight was not one of the pooled outcomes.
• The Finnish cohort. Laukkanen’s 2015 JAMA Internal Medicine study of 2,315 Finnish men linked frequent sauna use with lower cardiovascular and all-cause death over a median 20.7 years. It is observational, about death rather than weight, and cannot show the sauna caused anything.

So: one review sentence and one 18-person trial point toward small fat changes, and no trial we found tested sauna alone against a proper control for weight loss in ordinary adults. That is a reason for a bigger trial, not a claim.

Does an infrared sauna help you lose weight?

No better than a traditional one, on what we found, and possibly less, because it heats you less. Atencio and colleagues at the University of Oregon (American Journal of Physiology, 2025) put 20 healthy young adults through three kinds of passive heating, at least a week apart. Forty-five minutes in a far-infrared sauna at 45 to 65°C (113 to 149°F) did not raise average core temperature at all. Three 10-minute rounds in a traditional sauna at 80°C (176°F) raised it 0.4°C. Forty-five minutes in a 105°F hot tub raised it 1.1°C. The abstract does not report sweat or weight, but less heat strain is not a recipe for more of either.

Infrared cabins run at 120 to 150°F air, manufacturer-stated, and warm you differently; the infrared vs traditional page covers how. Some users report sweating as much in one, which is a user report, and sweat is water either way. Claims of several hundred calories a session, often given as 600 in 30 minutes, have no peer-reviewed measurement of oxygen use behind them that we could find. A University of Oregon trial of 30 far-infrared sessions in adults with obesity (NCT07158047) lists blood pressure and glucose as its primary outcomes, not weight.

Can a sauna help weight loss alongside exercise?

It can sit beside it, which is not the same as helping. If a sauna after training makes you more likely to train, it has done something useful; it does not add meaningful calories or make fat leave faster. Our session-length guide has the conservative post-workout pattern: 10 to 15 minutes at 150 to 170°F, after water and after your heart rate has settled. Do not log a post-workout, post-sauna weigh-in as progress, and never hold back water to make the number look better.

Sauna for weight cutting: why it is dangerous

Weight cutting is deliberate dehydration to make a weight class in wrestling, boxing, judo, MMA and other weigh-in sports. It is the one sauna use for weight that works as intended, because the goal is water, and the one with deaths attached.

Between 7 November and 9 December 1997, three previously healthy college wrestlers in North Carolina, Wisconsin and Michigan died while trying to make weight, the CDC reported in MMWR in February 1998. Each restricted food and fluid and exercised in the heat in vapor-impermeable suits under cotton warm-ups. One was trying to lose 15 lb in 12 hours; another, 4 lb in four hours, had a core temperature of 108°F at death. The CDC attributed the deaths to dehydration and hyperthermia. These cases involved suits and exercise, not saunas, but in January 1998 the NCAA banned saunas, steam rooms, hot rooms above 79°F, vapor-impermeable suits, diuretics and excessive food and fluid restriction for weight control.

The practice did not go away in other sports. Barley, Chapman and Abbiss’s 2019 review in Sports found saunas or heated rooms and sweatsuits to be the most common ways combat athletes induce sweating, with losses over 5% of body mass within 24 hours of a weigh-in reported, and found that cuts of about 5% in under a day impair repeated-effort performance. The International Society of Sports Nutrition’s 2025 position stand on combat-sport weight cuts accepts sauna and hot-water immersion as acute water-loss methods only “with appropriate supervision”, and puts the target at about 2 to 4% of body mass within 24 hours of the weigh-in, followed by planned rehydration before competing.

That is guidance for athletes with a coach, a scale and a rehydration plan, losing water on purpose for a weigh-in. It is not a weight-loss method.

Sauna suits are sold for weight loss too. Matthews and colleagues (Journal of Strength and Conditioning Research, 2022) measured 12 active adults doing high-intensity intervals with and without one: the suit added about 23 kcal, which the authors judged unlikely to benefit weight loss. What it reliably does is stop sweat evaporating, which is how you shed heat, and that is the mechanism in the 1997 deaths.

Who should not use a sauna to drop weight

Nobody should. These are the people for whom the heat itself needs a clinician’s say-so first:

• Anyone with heart disease. Hannuksela and Ellahham’s 2001 review in the American Journal of Medicine lists unstable angina, a recent heart attack and severe aortic stenosis as contraindications, while finding sauna safe for most people with stable coronary disease.
• Anyone on blood pressure medication. Kukkonen-Harjula and Kauppinen’s 2006 review (International Journal of Circumpolar Health) found medication generally no concern during a bath, except antihypertensives, which may predispose to a blood-pressure drop on standing after bathing.
• Anyone on diuretics (“water pills”). They already pull fluid out; a sauna takes more. Ask your pharmacist first, and never take one to make weight.
• Anyone who has been drinking. The same 2001 review says alcohol during sauna bathing raises the risk of low blood pressure, heart rhythm problems and sudden death, and should be avoided.
• Pregnancy. Both reviews above found no harm in uncomplicated pregnancies, but a 2005 meta-analysis of 15 studies (Moretti and colleagues, Epidemiology) found raised maternal temperature in early pregnancy roughly doubled the odds of a neural tube defect. Ask your obstetrician, and do not use heat to manage weight in pregnancy.
• Children and teenagers. Kukkonen-Harjula and Kauppinen found sauna well tolerated by healthy people from childhood to old age, which describes ordinary family bathing. Weight cutting in the heat is a different thing entirely, and it is what the NCAA banned after the wrestlers’ deaths.

How to weigh yourself in and out, and drink it back

Use the bathroom scale to know how much to drink, not to track progress:

1. Empty your bladder, towel dry, and weigh yourself in the same clothes, or none, before you go in.
2. Take your normal round: 10 to 20 minutes at 160 to 190°F at the ceiling sensor for a regular bather, 8 to 12 for a first session. Leave at any exit signal.
3. Towel off fully and weigh again in the same clothes.
4. Drink back roughly 1.5 times the difference over the next hour or two: about three cups (24 oz) for every pound lost, following the ACSM’s 1.5 litres per kilogram.
5. Treat a loss over about 2% of body weight in one session, 3.5 lb for a 175 lb adult, as a sign the session was too long or too hot. The 2% line is the ACSM’s threshold for excessive dehydration in exercise; it is a reasonable ceiling here.

Do this a few times and you will know your own sweat rate, which is worth more than any figure on this page.

What we have not measured

We have not weighed anyone in a sauna, logged a heart rate or measured a calorie. Every figure above comes from the study named beside it, and the calorie band is our reading of the ACSM equation at a MET value nobody has published for sauna bathing.

The test we owe is the one already named in our session-length guide: one subject, bladder emptied and towel-dried, weighed on a bathroom scale that reads to 0.1 lb before and after a 20-minute round at 180°F at the ceiling sensor, no water drunk in between, with room humidity logged. We would add fluid drunk afterwards and a next-morning reweigh, to show how much came back. Alongside it, heart rate on a chest strap through the round, the reading the contrast protocol page also owes. One person on one day is n=1: a description of that session, not of you, and we will not run a “lose weight in a sauna” trial on one person and call it evidence. How we test says the same about every figure on the site.

Where to go next

• How long and how hot a round should be: how long to stay in a sauna, with minutes by temperature and the exit signals.
• Which kind of sauna: infrared vs traditional, two different appliances rather than price tiers.
• If you are buying one for the habit, not the scale: the best home saunas.
• If you were sold on a blanket for weight loss: sauna blankets, and what the one measured session showed.
• Everything else on heat: the saunas hub.