The Science Of Sauna Weight Loss

So you’ve been eating right and you’re killing it in the gym. But you wonder if there was any way to burn a few extra calories and hit your weight loss goal faster. You’re also a bit sorer than you’d like to be post-workout and wonder if there was a way to ease the soreness whilst improving recovery. If any of that sounds like you then you’ll seriously want to consider adding a regular sauna session to your self care routine. Not only is the sauna a great way to blow off steam after a workout, but it also comes with a long list of health benefits to help you tone up and feel energised. In this article, I’ll break down what exactly sauna is and the science behind how it can help you lose weight.

Origins of Sauna

Before we can talk about the science and incredible benefits of sauna, we first have to touch on what exactly sauna is.

Sauna is an ancient health practice that dates back to over 2000 BC and originates somewhere in northern Europe. Although its exact place of origin is not known, the word Sauna is actually a Finnish word. Fun fact, Sauna is the only Finnish word in the English language.

Sauna just means ‘cabin’ but is popularly used to refer to a heated room in which people relax for the express purpose of sweating a lot. And I mean a lot. The average person sheds about a pint of sweat during a short 15-minute sauna session.

But this is only one type of sauna, let’s quickly touch on the different types of sauna.

Types of Sauna

Traditional Sauna

Traditional saunas are the original Finnish type of sauna. Conventionally these are wood-burning saunas. Wood-burning saunas heat up sauna rocks which in turn radiate heat to the room. The humidity in the room can be adjusted by pouring water over the sauna rocks.

This traditional style of sauna takes a bit of time to heat the room up, demands a vigilant eye to control the heat and humidity, and necessitates good ventilation. Modern ‘traditional’ saunas overcome many of these challenges by electrically heating the sauna as opposed to using wood burning. This allows for fine control of heat and humidity.

Traditional wood-burning and electrically heated sauna are known for their extreme heat, with temperatures ranging from 160 – 200°F (71-93°C). The humidity is low so the air is desert-dry.

Steam Room

Steam rooms are, as the name implies, rooms heated with steam. Water is boiled in large generators which collect and pump the steam into an enclosed room.

The thing that makes steam rooms unique is that they maintain a tropical wet environment with humidities of nearly 100%.

The tradeoff with steam rooms is that they do not generate the same intense heat as traditional saunas, instead maintaining respectable temperatures around 120°F (49°C).

Infrared Sauna

Infrared saunas are the newest, most technologically advanced form of sauna that we have. These use infrared light, a type of electromagnetic radiation that has a longer wavelength than visible light meaning it cannot be seen.

But do not worry, it is not harmful. Infrared light is non-ionising which means it does not cause damage to cells or DNA. In fact, we produce low levels of infrared light ourselves! Want to test it out? Place your hand next to your cheek. After a few seconds, you’ll feel a warm glow on the cheek. That’s your body’s infrared heat!

This deep heating effect means infrared saunas can use lower heat temperatures, typically between 100˚F (38°C) and 130˚F (54°C).

If you’re keen to try one out, check out my article on the best infrared sauna available currently.

The Science Behind Sauna Weight Loss

So, we understand the different types of sauna options available to us but how can sauna help us lose weight? Let’s dive into the science behind exactly how getting your sweat on can help with getting the weight off.

Water Weight 

The most straightforward way that sauna causes weight loss is by cutting water weight. As mentioned before, sitting in a sauna will cause you to sweat a lot, with the average person sweating up to a pint in volume during a short session.

Remember, humans are 70% water. So it’s not unheard of for people to experience up to five pounds in weight loss after an intense sauna session. This is why athletes and bodybuilders regularly use saunas when they need to cut to a certain weight rapidly.

However, cutting water weight is not a sustainable weight loss method. Not only is there a risk of dehydration, but the water weight returns immediately after you rehydrate. So overall losing water weight is not an effective weight loss strategy.

Fat Loss

It was previously thought that sauna was only good for losing water weight however, there is increasing evidence that sauna can actually help people to burn more calories, and in turn, burn fat.

Mitochondria

There is evidence that heating the body up causes a change in the number and mitochondria within a muscle. Mitochondria are responsible for your base metabolic rate i.e. how much energy you burn daily. More mitochondria = more calories burnt = more weight loss.

One study found that mice who were only passively heated experienced the same amount of fat weight loss as those who did regular treadmill running. And even better, the mice that were both heated and exercised experienced an astounding fat weight loss of 72% (1).

Heat Shock Proteins

Heat Shock Proteins (HSPs) are produced when the body is subjected to high temperatures, such as in a sauna. These were originally thought to just the body against heat but more data is revealing that HSPs can also help you lose weight.

One study compared people receiving heat shock treatments two, four, and seven times per week. The four-treatments-per-week group lost more abdominal fat and had better blood fat levels than the two-treatments-per-week group. And the seven-treatments-per-week group enjoyed even more weight loss than the four-treatments-per-week group (2).

Another study compared two groups of mice; one with high levels of HSPs and one with normal levels. Both were fed a high-fat and high-calorie diet. The mice with high HSPs did not gain weight after 10 weeks, whereas the mice with lower HSPs experienced 30% weight gain (3).

Growth Hormone

Another emerging theory behind the use of sauna for weight loss is that sauna stimulates the production of Human Growth Hormone (HGH). HGH is known to both stimulate the breakdown of fat and prevent the storage of fat.

One study found that, in both men and women, sauna use resulted in a 16x increase in HGH levels (4). That’s a lot of muscle growth and fat burn!

Another study found that using infrared sauna three times a week for thirty minutes per session resulted in an average fat weight loss of 4% over a four-month period. For a 175-pound man, that represents a weight reduction of seven pounds (5).

How Can I Incorporate Sauna Into A Healthy Lifestyle?

I’m sure that was a lot of scientific data to take in. But the take-home message is that there is also a growing body of scientific work that shows how and why a sauna is a potential weight loss tool.

So you’re convinced. You want to start adding regular sauna sessions to your health routine but you’re not sure where to start. Should you go for a dry traditional sauna, splash around in a steam room, or go high-tech with an infrared sauna? My advice is to go for infrared.

Infrared Sauna

The reasons I prefer infrared sauna are:

• Infrared light penetrates skin roughly 2 inches deep and heats tissues from the inside out. This generates a deeper more intense sweat
• The deep heating mechanism of infrared saunas means you can enjoy a great sweat even at lower temperatures. Because the temperatures are lower you can tolerate longer sauna sessions for potentially more health benefits
• They’re relatively affordable and can be done at home

A Word Of Caution

As with any health practice, although there are many benefits, there are also risks that you need to be aware of. As a general rule, avoid saunas without first speaking to your doctor if:

• pregnant
• immune-compromised
• have a history of heart disease
• have a low blood pressure
• are sick or have a fever

Even if you are healthy and able to safely enjoy a sauna, always watch out for dehydration and ensure you adequately rehydrate after each session.

Conclusion

Sauna is a rejuvenating practice that has many health benefits including losing weight. Although we have discussed a lot of the science behind how a sauna can help you lose weight, the optimal way to tone down is to maintain a healthy diet and do regular exercise. If you mix in sauna sessions with these two things I’m confident you’ll have no problem losing weight. And if you want an extra fat-burning health boost then why not try out an ice bath. Happy sweating!

Sources:

1. Postexercise whole body heat stress additively enhances endurance training-induced mitochondrial adaptations in mouse skeletal muscle Yuki Tamura, Yutaka Matsunaga, Hiroyuki Masuda, Yumiko Takahashi, Yuki Takahashi, Shin Terada, Daisuke Hoshino, and Hideo Hatta American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 2014 307:7, R931-R943
2. Kondo T, Goto R, Ono K, Kitano S, Suico MA, Sato M, Igata M, Kawashima J, Motoshima H, Matsumura T, Kai H, Araki E. Activation of heat shock response to treat obese subjects with type 2 diabetes: a prospective, frequency-escalating, randomized, open-label, triple-arm trial. Sci Rep. 2016 Oct 19;6:35690. doi: 10.1038/srep35690. PMID: 27759092; PMCID: PMC5069544.
3. Activating HSP72 in Rodent Skeletal Muscle Increases Mitochondrial Number and Oxidative Capacity and Decreases Insulin Resistance. Henstridge DC, Bruce CR, Drew BG, Tory K, Kolonics A, Estevez E, Chung J, Watson N, Gardner T, Lee-Young RS, Connor T, Watt MJ, Carpenter K, Hargreaves M, McGee SL, Hevener AL, Febbraio MA. Diabetes. 2014 May 15; 63(6): 1881-1894
4. Leppäluoto J, Huttunen P, Hirvonen J, Väänänen A, Tuominen M, Vuori J. Endocrine effects of repeated sauna bathing. Acta Physiol Scand. 1986 Nov;128(3):467-70. doi: 10.1111/j.1748-1716.1986.tb08000.x. PMID: 3788622.
5. https://www.infraredsauna.co.uk/resources/infrared-sauna-weight-loss