A Sauna Isn’t a Substitute for Exercise

Spending time in a sauna can feel good, but it can also entail a little bit of suffering; after all, if the weather outside were the same as the temperature in a sauna, you’d probably want to hide out in the air conditioning all day. There’s something about unpleasant bodily experiences that makes us think they must be good for us, somehow, and so the sauna has gained a healthful reputation that it doesn’t entirely deserve. Here’s a rundown of what a sauna can and can’t do for you.

Saunas don’t burn fat

It is technically true that you can lose weight by sitting in a sauna, but that’s not because your body is torching fat; it’s because you’re sweating, and sweat is made of water, and water weighs something. As soon as you rehydrate—which you should—the scale will go right back to where it was at the beginning. After all, as I’ve discussed in the context of exercise, sweating doesn’t mean that you got a good workout or that you burned calories. It just means you were hot.

People who sell saunas and sauna services like to talk up their calorie-burning benefits, but there’s no evidence to suggest you burn significantly more calories sitting in a hot room than you would sitting on your couch at home. Some more skeptical websites cite a modest figure of 1.5 to 2 times as many calories as you would burn sitting at room temperature, but without a citation. If true, that’s about the same as the difference between sitting and standing—so you can skip that trip to the sauna and just spend half an hour standing around.

So why does your fitness tracker say you burned a ton of calories in the sauna? First of all, don’t bring your phone in the sauna, it’s bad for the battery. But since you did anyway, I’ll explain. The calorie-burning algorithms on your watch are built to estimate your calorie burn from your heart rate under the assumption that you are exercising. If your heart rate increases but you are not exercising, the calculations aren’t correct. The calorie burn during exercise comes from the fact that muscles all over your body are contracting over and over again. That is simply not what’s happening when you sit in the sauna.

Saunas don’t “detox” you

It’s 2026 and we as a society should be over this “detox” concept, which has been debunked time and time again. Ordinary inconveniences like being tired sometimes aren’t due to some secret toxins that are constantly poisoning you, and even if you do have health issues due to toxins, you should seek medical treatment and not expect smoothies or saunas to cure you.

Saunas don’t replace exercise

Saunas and exercise both heat up your body and make you sweat, but there aren’t many similarities aside from that. Remember, exercise makes us stronger and improves our cardiovascular endurance (giving us a higher VO2max, for example). Sweating in a hot room doesn’t do that.

Even this rundown from an exercise science researcher, whose headline draws parallels between running and sitting in a sauna, includes the following disclaimer: “Before you contemplate cancelling your gym membership and investing the savings in a Jacuzzi, know that regular saunas or baths are unable to replicate all the health benefits of exercise training, such as promoting fat loss and increasing muscle mass. Using hot baths or saunas shouldn’t be considered as a substitute for exercise.”

Saunas may be good for your blood vessels

What that researcher does point out, after the disclaimer, is that there are a few lesser-known benefits of exercise that seem to be related to the increase in body heat and heart rate, rather than from the more obvious strain on our lungs or muscles.

When your body temperature rises, blood vessels near the surface of your skin dilate (get wider) and this process may help cell growth and repair. In other words, simply raising body temperature may be good for your blood vessels. That’s not something we normally think about, but healthy blood vessels are a part of a healthy cardiovascular system.

Relaxation is real

If you find saunas relaxing—and many of us do—that can be a health benefit in itself. Now, this isn’t as concrete a benefit as it’s sometimes made out to be. You’re not going to cure your depression or reverse your heart disease just by relaxing in a sauna every now and then. But if you enjoy your sauna sessions, they could certainly contribute to lowering your stress levels and improving your mental health. Pro tip: If you don’t have access to a sauna, a hot bath may have a lot of these effects as well.

Heat has its pros and cons

For other medical conditions and athletic uses, the pros and cons of a sauna come down to the pros and cons of heat itself. If you have sore muscles, heat often feels good, so athletes often enjoy sauna sessions.

Some skin conditions respond well to the dry air of a sauna, while others can be exacerbated by dry air but could feel better with the humid air of a steam room. Use common sense and check with your medical provider if you want to use a sauna to manage a health condition.

Saunas have risks, too

If we’re talking about health benefits, it’s only fair to discuss risks as well. Saunas are reasonably safe, but people with medical conditions are often advised to steer clear, or to talk to a doctor before deciding to spend time in a sauna. This may include you if you are pregnant, have unusually high or low blood pressure, have epilepsy, or are taking stimulants, tranquilizers, or mind-altering drugs. Spending time in a sauna has also been linked to temporarily lowered fertility because heat impairs the production of sperm.

The main danger of a sauna is that you could overheat or dehydrate; severe heat illness and dehydration can both be life threatening, and people have died in saunas. Alcohol makes you more susceptible; half of the people who died in saunas, according to a Finnish study, were under the influence of alcohol. (The authors argue that the biggest danger is not alcohol itself, but allowing a drunk person to be in a sauna alone.) So if you choose to spend time in a sauna, be smart about it. Hydrate well, don’t go alone, and don’t expect the sauna to do things that saunas can’t do.