Regular sauna users live longer and have a significantly decreased risk of every disease there is. That’s an amazing fact that has been substantiated in several studies. But saunas can dehydrate you. So how much water do you really lose when you take a sauna? Do some people lose more water than others? And finally, what about weight loss? Is taking a regular sauna a good way to lose fat? The answers may surprise you.
Recently scientists reported on a series of sauna experiments in an article entitled, “Sauna-induced body mass loss in young sedentary women and men.” They were looking to see how dehydrated people get when they take a sauna. They also wanted to see if some people became more dehydrated than others from the same amount of time and temperature in the sauna.
So they took a group of 674 sedentary men and women between the ages of 19-20. Their weights ran the gamut from being thin to being obese. They put the students in a dry sauna for two sessions of 10 minutes each with a five-minute break. Then they measured how much weight they lost and how much of it was water. They also looked to see if being overweight played any role in how much water they lost. Here’s what they found.
Once you get in a sauna, the sweating begins right away and reaches its maximum at approximately 15 minutes. The average water loss was 0.5 kg. That’s a little over a pound of water. That amounts to about 16 ounces of water by volume. But the researchers also discovered that there was a “considerable variation” in individual sweat rates. In addition, they found that the amount of water loss each person had was directly related to their weight. The more a person was overweight, the greater their water loss. The heaviest people lost more than twice as much water as those who were thin. “Persons with a high BMI [overweight and obese] are at higher risk of dehydration, and they should pay particular attention to replenishing fluids during a visit to the sauna.” Here are a couple of other points.
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First, when you take a sauna and see a difference on the scale afterward, the difference is almost entirely water loss. So make sure that you replace that water loss right away. For every pound of weight loss, drink 16 ounces of water with two pinches of salt. The authors also gave some interesting information about hydration in general.
“It must be noted that for a person with a sedentary to active lifestyle, the average daily water demand is two to four quarts in a temperate climate and four to ten quarts in a hot climate. Persons performing light exercise in protective clothing generally lose 1.0-2.5 quarts of water every hour.” That’s way more than I would have guessed. Individuals consuming a normal diet do not have to drink electrolyte supplements except when exercising or working for more than an hour in a hot environment. But what about fat loss. Can’t you lose fat in a sauna?
I’m sorry to say, the amount of fat that can be burned in a sauna is minimal. In fact, if you’re sitting in a sauna, you’re only going to burn about 50-100% more calories than if you were just sitting in the living room. So here’s how this works out. A healthy male of 185 pounds burns about 42 calories in 30 minutes of sitting. To find the number that this same man burns while sitting in a sauna for 30 minutes just multiply 42 calories by 1.5 to 2 in order to get an estimate.
In this case, the individual would burn roughly 63 to 84 calories. That’s only a maximum of 84 extra calories per hour from sitting in the sauna. Since it takes about 500 calories to burn a pound of fat, this man would have to spend a minimum of six hours in a sauna to lose one pound. Surely there must be a better way to lose fat!
So to sum it all up. One, it’s a great idea to use a sauna regularly. The more often you take a sauna, even every day, the healthier you will be. Two, make sure to replace your water and salt loss. Three, when you are working or exercising in hot climates, notice how much water you can lose and be sure to replace it. Being chronically dehydrated is common for so many people. And it’s very unhealthy. I have a whole chapter on this in my book Bursting With Energy. Four, if you need to lose weight, do not plan on doing it with a sauna.
Yours for better health,
Frank Shallenberger, MD
Podstawski R, Boraczynski T, et al. Sauna-induced body mass loss in young sedentary women and men. ScientificWorldJournal. 2014;2014:307421.