The fitness industry is constantly bombarded by waves upon waves of misinformation, and saunas seem to often be the center of all that. I am not saying that what you read up online isn’t true but it is often greatly exaggerated or slightly distorted. Whether saunas can help you lose weight or not has been the topic of countless discussions and even scientific research and the results should always be taken with a grain of salt. Even what I am about to share with you here might differ from person to person a little but is still valid when interpreted freely.

Right off the bat, if you’ve ever found a source that claims that you can burn up to 1000 calories for a 30-minute sauna session, rest assured that this is quite far fetched and here is exactly why…

Imagine the most intense HIIT (high-intensity interval training) can only reach a rate of caloric burning of around 15 calories per every minute you train. If you’ve ever been into such a training session, you would know that sustaining that tempo for more than just a few minutes is extremely difficult and is often not recommended by professionals. So, following that logic, how would sitting inside the cozy wooden sauna burn anywhere between 10-30 calories per every minute? Exactly, it isn’t possible.

I am not saying that you aren’t burning more calories when heated up in the sauna, I am just saying that it is nowhere near that often quoted number. Let me elaborate…

Calories And Sauna

Saunas can be wood-burning, electrically heated, or infrared. All that these types have in common is that they all heat up your body quite a lot one way or another. Since your core body temperature increases there are a number of processes that start taking place:

  • Your metabolism levels increase
  • Your blood flow improves
  • Your heart rate goes slightly up

All that is thanks to the raised temperature. The increased metabolism and heart rate are two of the things that support the theory that calorie-burning increases during this process. While this is technically correct, it is in no way increasing your normal caloric burning rate (1-2 calories per minute) to that staggering number of 30 calories per minute. Studies have shown that, at best, a regular sauna session increases your calories burned twofold.

So, to use a simple equation to solve your question, calculate the number of calories your body burns for 30 minutes of sitting (taking your body weight into account) and multiply that by 1.5 or 2. The result will be the calories burned inside a sauna for that duration, and you might already find that it is nowhere near a few hundred calories.

An average person will burn around 40 calories when sitting for half an hour, meaning that in a sauna they will expend no more than 80, which is the equivalent of around 5 minutes of any high-intensity workout.

So, in reality, you are burning more calories when just chilling in the sauna, it just isn’t as much as you (or I) wished it would be.

Click here if you want to see some of the top infrared sauna models for this year that can help you lose weight!

What about weight loss?

Enjoying sauna heat

Everyone who has stepped in and out of a sauna knows that he or she will drop a pound or two depending on the temperature and humidity of the sauna. So what is that all about? Well, since the dry air inside the sauna allows for a lot of sweating (water evaporates easier from your skin), then you will be losing water from your body at quite the fast pace. So, technically you will weight a little less when you go out, but that weight should be immediately replenished by water otherwise you will be dehydrating your body and possibly causing stress to your circulatory system and organs.

Moreover, losing all that weight solely from water makes it harder to shed those extra pounds in the long run as proper hydration is a key player in burning extra pounds.

Consistent and healthy habits are the factors that lead to a healthy pace of weight loss while shedding pounds of body-water inside the sauna isn’t.

The Dangers Of Dehydration

As I pointed out, heat makes your body sweat. Sweating means losing fluids through your skin. When you lose more fluids than you take in, your body starts dehydrating. Sauna, naturally, is a way to lose water, so replenishing it must be a key part of your session, otherwise, you will just lose more water which is essential to your body’s function. Some sauna models let you control their humidity levels which, in turn, controls how much you sweat but it still is a very efficient way to lose body water.

So, what are the potential dangers of dehydration and which are the signs that you need to look for?

Signs

When you are in the sauna it is crucial for you to pay attention to any potential signs of dehydration, as severe dehydration is a quick way to win a visit to the ER. Here are some of the most common signs of dehydration:

  • Extreme thirst
  • Dryness in eyes and mouth
  • Lightheadedness, dizziness, and headaches
  • Less frequent urination

All these are directly linked to your body quickly losing fluids. Your brain is the most sensitive organ when it comes to water and the moment you start losing it without properly replenishing it, your brain will start sending out distress signals usually in the form of pain or dizziness. Having a dry mouth is also a clear signal by your body that it needs more water to function properly. Unlike with food substances, we don’t have a reservoir for water and the body cannot self-regulate these levels once it starts sweating as much as it does in a sauna.

How to avoid it

To avoid these you need to properly re-hydrate yourself before, during, and after the sauna. On average, you will lose around 2 pints of water per 15 minutes in the sauna. So, it is pretty safe to assume that drinking 3 pints of water back after a normal 20-minute session should do the job at keeping your water levels constant. People that suffer from conditions such as kidney disease, diabetes, or heart failure, are at higher risk of getting dehydrated.

If you’ve just been in the gym and have been sweating profusely there, you also need to take that into account when trying to figure out how much water to drink in order to restore the balance. One common mistake people do is head to the sauna immediately after the gym and then re-hydrate only taking the sauna into account. That negative water balance can disrupt a lot of processes that are linked to your muscle restoration in the following hours and days.

Good infrared saunas still offer a lot of advantages, even if weight loss isn’t one of them. You can click here if you want to learn how infrared light inside those saunas helps your body.

The Sauna And Your Heart

There are a few direct effects that heat has on your body that are all related to your cardiovascular system. Firstly, your smallest blood vessels (the capillaries) dilate. This allows blood to move closer to the surface of the skin and therefore more water will be able to pass through and evaporate (increased sweating). By dilating, these blood vessels also drop the overall blood pressure in your cardiovascular system. This is one of the main advantages of saunas and it is extremely healthy for people that are suffering from hypertension.

There have been studies that even point out a direct link between regular sauna visits and improved cardiovascular health. Still, if you have pre-existing heart conditions like a recent heart attack or irregular heart beating, you should avoid places that get that hot. People that have irregular blood pressure should also avoid alternating between hot and cold environments or big temperature swings in general.

Have in mind that inside the sauna your heart rate will also increase. This will result in your body burning slightly more calories, as discussed, but won’t really affect your fat tissue metabolism too much. One other reason why this is important is that the increased heart rate can postpone the beginning of the healing phase of your muscles. Sure, the heat will relax your whole body, but in order for your muscles to start rebuilding themselves, they will need a resting heart rate, and the passively increased HR from the sauna won’t allow it.

I’ve compiled a whole article on the topic of workout recovery and saunas. Click here to check it out.

Final Words

So, can saunas help you lose weight? Well, technically yes but actually no. Almost all the weight that you lose during a 20-30 minute sauna session is pure water evaporated from your skin’s pores and should be replenished as soon as you step out or even during the session itself. The slight surplus of calories burned is solely thanks to the increased heart rate and metabolic rates. These aren’t enough to justify using saunas or even steam rooms for losing weight, though, and that can be quite counterproductive in the long run.