Several years ago, I worked for a finish company (Yes, NOKIA) and had the pleasure to visit the country several times. During one of my trips, I was invited to real finish sauna. Finally, I was about to try the real deal, instead of the standard ones at the hotels.
There was nothing fancy about the place. In fact, it looked a bit cheap. It was only locals, most of them above 70 years old.
I remember the heat was terrible, much hotter than I had ever tried.
Some of the elder people started to laugh at me and my German friend as they could see how we were struggling in the heat. Whereas they seemed to be enjoying it so much, that even some of them wore a knitted cap on their head.
After like 15 minutes we couldn’t stand the heat any longer and went outside to dip ourselves in the leg where a hole had been cut in the ice. The experience was fantastic and is still one of my best travel memories.
We didn’t go to the sauna for weight loss and from what I remember, the local people who seemed to come there often and actually could stand the heat for a long time didn’t seem that slim either. However, the question is, if sauna for weight loss is a myth or truth?
If we Google it, we get almost as many answers as we click links. Everything from 0 extra calories burned to 500 calories burned in 20 minutes. Some even say that your metabolism slows down when you enter a sauna. When it comes to lbs, you can find comments saying, that you only lose the amount of water you sweat and others claiming you can lose 5 lbs in 30 minutes.
The question is how should we navigate through all these comments in order to find the right answer?
So if we leave the fantastic feeling of being in a sauna – or getting out of it 🙂 and just objectively start to calculate the number, what do we get?
Basal metabolic rate
First, we need to have a foundation to calculate out from. For that, we will use the basal metabolic rate (BMR).
This is the minimal amount of energy our body is using during the time. If we take the sauna situation, most people are resting, so they will be very close to minimal energy usage. Of course, we need to consider the heat, but as we do not know yet if the heat has an impact, we will leave that question out for now and just assume that during a sauna session, we are close to BMR state.
To calculate a 100% accurate basal metabolic rate is difficult. This as body composition, age and gender has a big impact. The trickiest part is the body composition, as more muscles means a higher BMR (This is why strength training is great for weight loss)
However, if we can live with rough figures and go for an average body when it comes to muscles, we can simply use these formulas:
Or if you want, go to this site and enter the figures 🙂
In our example, we take a woman, 35 years old, 165cm high (sorry, I’m from Europe) & 65kg. For this person, the BMR will be 1355 calories a day or around 56 calories an hour.
So we now know that this woman will roughly burn 56 calories an hour at rest under normal conditions. But what if we put her in a sauna?
The rise of external temperature.
Two things happen when you go into a hot sauna.
You will start to sweat
Your body temperature will rise
The question is how does this impact the BMR, if anything at all?
So when we workout, we normally sweat. We know that working out can raise our metabolism up to 5 times, so a normal belief is that we raise out metabolism when we sweat – however, this has very little truth to it. Remember it’s not just the sweating and raised heart rate – it’s actually your muscles working and thereby requesting more energy.
Of course, the sweating is an additional activity that requires energy, but as this is triggered by external heat, it also means that your body can slow down on its own production of heat. Therefore, it more or less equals out each other.
Conclusion: Sweating due to external heat will not raise your BMR
Raised body temperature
With raised body temperature like a fever, it’s a bit different. Actually, the BMR will increase by 14-15% by every degree Celsius when the body temperature rises.
The question is then of course how much does the body temperature rise during and after a sauna visit?
Studies have shown that in adults, a 30min visit in a 80-degree hot sauna, will raise the body temperature by 0,9 degree.
Ok, we now got some numbers – let’s try to calculate roughly.
From above we know that our body temperature will rise to 0.9 degrees after 30min of moderate hot sauna. Now, let’s be fair and say that we had 90 degrees, and it takes another 30min to cool down. In that case, we raised our body temperature with 1 degree for one hour. Meaning the BMR raises with 15% for 1 hour.
In the case of our example, that means additional 15% of 56 calories. Equalling in an additional 8,5 calorie burned during that hour.
Sauna for weight loss?
I believe we now are able to answer the question if sauna for weight loss is a myth or the truth.
As a rough thumb of rule, we know that it takes around 3500 calories to burn 1 pound of fat. Therefore it would take around 411 sauna visits of 30min duration to lose 1 pound of fat.
So what do you think? Does 411 sauna visits seem like a good way to loose 1 pound of fat? 🙂
Not really, right?
Just for fun lets compare it with the exercise called Burpee. Doing 1minute of burpees will roughly require 10 calories, so here you would have to do burpees for almost 6 hours to lose 1 pound of fat. Not the best option but still much faster than the sauna.
I hope you get the picture. Sauna for weight loss is close to being a waste of time. However, we of course, shouldn’t forget about the great feeling of being in a sauna or getting out 🙂 Therefore, enjoy your sauna sessions for whatever reason, but do not expect a weight loss.