How many calories you burn in a sauna, and why the scale lies afterwards
The only study with minute-by-minute sauna expenditure found 73–131 kcal for every 10 minutes, about 400 kcal over four rounds. But that is a sports watch estimate based on heart rate, not a measurement, and even taken at face value it equals about 50 g of fat. The half-kilo drop on the scale after a sauna is sweat, and it comes back with your first cup of tea.
How many calories a sauna burns
Minute-by-minute sauna expenditure was recorded in the Polish study by Podstawski and colleagues (2019). 45 young men with overweight, averaging 86 kg, did four 10-minute rounds in a dry sauna at 90–91 °C with five-minute breaks.
| Round | kcal per 10 minutes |
|---|---|
| First | 73 |
| Second | 94 |
| Third | 115 |
| Fourth | 131 |
| Total for 40 minutes in the heat | 414 |
Expenditure rose with each round because heart rate rose. Heavier participants burned more.
Expenditure was not measured by gas exchange, though. It was calculated by Suunto watches from heart rate. Such formulas are built for exercise, when heart rate rises along with muscle work. In heat, heart rate rises for another reason — the heart pumps blood to the skin to shed heat — so real expenditure is probably lower than shown.
If you take these figures anyway, the first 30 minutes in the heat come to about 280 kcal. For comparison, a kilogram of fat tissue holds about 7,700 kcal, so 414 kcal corresponds to roughly 54 g of fat.
Where the half-kilo drop on the scale comes from
In the same 45 men, the scale showed an average of 0.65 kg less after the one-hour session. According to the summary in an earlier paper from the same group (Podstawski and colleagues, 2014), a typical sauna session costs about 0.5 kg of sweat. In 674 students after two 10-minute rounds, the loss ranged from 0.24 kg in lean women to 0.82 kg in men with overweight.
That is water. It needs replacing, and the weight comes back as soon as you drink. Why the scale jumps by half a kilo to a kilo in a day is covered in the article on daily weight fluctuations.
Does regular sauna use lead to weight loss
In the study by Toro and colleagues (2021), 12 young men had 12 sauna sessions at 100 °C, and another 11 served as controls. Body composition was measured by DXA. Fat mass did not change after the course, and neither did body weight.
A sauna does not hurt weight loss, but it replaces neither a calorie deficit nor exercise. How much walking, swimming and strength training burn is covered in the article on calories burned during exercise. "Sweating out toxins" does not work either — see the article on detox myths.
What to keep in mind before a sauna
- Drink water between rounds and afterwards: sweat takes away both fluid and salt. How much water you need on an ordinary day is in the article on daily water intake.
- Do not drink alcohol. The review by Hannuksela and Ellahham (2001) names alcohol in the sauna as a cause of low blood pressure, arrhythmia and sudden death.
- The same review lists unstable angina, a recent heart attack and severe aortic stenosis as contraindications. With other heart conditions, high blood pressure, pregnancy and in old age, sauna habits are worth discussing with a doctor.
- Do not weigh yourself straight after the sauna if you are tracking weight trends: the number will be too low.
How regular sauna use relates to heart health is covered in the article on sauna and the heart.
How to log a sauna in your diary
If you log expenditure, you can leave the sauna out or enter it modestly, as a gentle walk of the same length: watch readings in the heat are inflated for the reasons above. What you eat and drink after the sauna is worth logging, though. Beer, kvass and snacks easily outweigh the whole expenditure; FoodGPT counts them from a photo of the table.
Frequently asked questions
- How many calories do you burn in a sauna in an hour?
- According to the only study with minute-by-minute data, young men weighing about 86 kg burned 414 kcal over 40 minutes in the heat. But expenditure was calculated by watches from heart rate, and in heat heart rate rises without muscle work, so the real figure is probably lower.
- How many calories do you burn in a sauna in 30 minutes?
- According to Podstawski and colleagues, about 280 kcal for the first 30 minutes in the heat, with the caveat that this is a heart-rate estimate, not a measurement.
- Why do I weigh half a kilo less after a sauna?
- That is sweat. A typical sauna session costs about 0.5 kg of water, and 0.65 kg after the one-hour session in the Podstawski study. The weight returns as soon as you replace the fluid.
- Can you lose weight by going to the sauna often?
- Not because of the sauna. In the study by Toro and colleagues, 12 sessions at 100 °C changed neither fat mass nor body weight. Weight is lost through a calorie deficit, and a sauna does not create one.
- Who should stay out of the sauna?
- The contraindications in the review by Hannuksela and Ellahham are unstable angina, a recent heart attack and severe aortic stenosis. Alcohol in the sauna raises the risk of low blood pressure, arrhythmia and sudden death. With other heart conditions and during pregnancy, discuss sauna habits with a doctor.
Read next
- Sauna and the heart: what the Finnish cohorts showed and where the link ends and the conjecture begins — The sauna often appears in biohacking not because there are robust trials on it, but because it has a compelling curve from Finnish cohorts: the more often people visited the sauna, the lower their cardiovascular mortality.
- Why weight changes by a kilogram in a day — Fat cannot be gained overnight: a kilogram of adipose tissue is thousands of kilocalories that cannot be acquired in eight hours of sleep.
- How many calories are burned during a workout: running, cycling, swimming, gym — An hour of running at a moderate pace for a 70 kg person is about 550–700 kcal, cycling at a leisurely pace is 350–450, swimming is 400–600, and strength training is 200–350.
This article is for general information. It is not medical advice, a diagnosis, or a prescription for treatment or a diet, and it does not replace a consultation with your doctor. If you have a health condition, are pregnant, take medication, or follow a diet prescribed to you, decisions about food belong with your doctor.
Figures from regulations, guidelines and studies are given as they stood when this article was prepared and may since have changed; check them against the primary sources. This article is not advertising, an offer, or individual advice, and neither the author nor the site owner is responsible for decisions taken on the basis of it.