Does a sauna help you lose weight?
By the Find My Sauna team·
Updated ·
6 min read
Step on the scales after a sauna and the number is often lower than before you went in. It's easy to see why so many people believe saunas help with weight loss. The truth is less exciting, but there's still a place for the sauna if you're trying to lose weight.
The short answer
Not directly. The weight you lose in a sauna is water from sweating, often half a kilo (about a pound) or more in a session, and it comes back as soon as you drink. Sitting in the heat burns slightly more energy than sitting still at room temperature, but far less than exercise. A sauna can support weight loss indirectly, by helping you relax, recover and stick with exercise, but it won't burn fat on its own.
Why the scales drop
When you heat up, your body cools itself by sweating. In a hot sauna, you can lose a lot of sweat quickly. Half a kilo in a 15-minute round isn't unusual, and over a long visit it can be more. Sweat is almost all water, with a little salt.
That water has to be replaced, and it should be. Once you drink, your weight goes back to where it was. Not drinking isn't a shortcut: being dehydrated makes you tired, gives you headaches and can make you feel faint.
How many calories does a sauna burn?
Some websites and sauna sellers quote huge numbers, like 300 or even 600 calories a session. Those figures don't hold up. In the heat your heart beats faster, a bit like during a slow walk, so you do burn somewhat more than sitting on the sofa. But you're still sitting still. Compared with any real exercise, the extra energy is small.
A good way to think about it: a 20-minute sauna session burns far less than a 20-minute brisk walk, and the walk doesn't leave you needing to replace a litre of fluid.
Can heat burn fat?
Not in a way that matters for weight loss. Your body doesn't need to burn fat to cool down. It uses sweat. There's no good evidence that regular saunas reduce body fat on their own. Belly wraps, sauna suits and "sweat belts" work the same way: you lose water in one spot, and it comes back.
How a sauna can still help
A sauna isn't a fat burner, but it can make the things that do work a bit easier:
- Recovery. Many people feel less stiff after a sauna, which can make it easier to train again the next day. See sauna before or after a workout.
- Relaxation and sleep. Poor sleep and stress both make healthy eating harder. Many regular sauna users say they sleep better.
- A healthy routine. If a weekly sauna becomes your reward for a week of training, that's a good habit.
- Heart health. Regular sauna use is linked to better heart health in long-term Finnish studies, whatever your weight. More in sauna benefits.
Sweating to make weight
Combat sport athletes and jockeys have long used saunas to drop weight before a weigh-in. It works on the scale because it's water loss, and it's risky. Losing a lot of fluid fast can cause dizziness, cramps, heat exhaustion and worse, especially combined with not eating or wearing heavy clothing in the heat. Don't use a sauna to sweat off weight in a hurry.
What about infrared saunas?
Infrared studios often make the boldest calorie claims. The same rules apply: you sweat, you lose water, you drink, it comes back. Infrared saunas run at a lower air temperature, so you can sit in them longer, but they're not a fat-loss tool. Read infrared sauna benefits for what they're good for.
Using a sauna while losing weight
- Weigh yourself on a normal morning, not straight after a sauna.
- Drink water before and after. Roughly replace what you lose.
- Don't go in hungry or after a very hard, long workout without eating.
- Keep rounds to 8–15 minutes. Longer isn't better. See how long to stay in a sauna.
- Never mix sauna and alcohol.
This guide is general information, not medical advice.
Find a sauna near you
Hornstullsbastun
Stockholm · Waterside sauna
Iglupark
Tallinn · Igloo saunas
Rooftop Saunas Hackney
London · Rooftop sauna
Frequently asked questions
How much weight do you lose in a sauna?
Often half a kilo (about a pound) or more in a session. It is almost all water and comes back when you drink.
Does sitting in a sauna burn fat?
No, not in any meaningful amount. Your body cools down by sweating, not by burning fat.
How many calories does a 20-minute sauna burn?
Somewhat more than sitting still, but far less than a 20-minute walk. Claims of hundreds of calories are not backed by good evidence.
Is it better to use the sauna before or after exercise for weight loss?
After. Going before can leave you dehydrated and tired for your workout.
Do sauna suits help you lose weight?
Only water weight. They also raise the risk of overheating, so they are best avoided.
