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There are a bunch of sites claiming this, with the most disparate theories: that saunas directly melt fat, that saunas burn calories because your body needs to maintain the normal temperature, that saunas increase your metabolism, that they make your heart work harder...

I also found a ton of suspicious pages like this one.

While there are a million theories, has anyone measured if any extra calories are burnt at all? If so, does sitting idly in a sauna burn significantly more calories than sitting idly elsewhere?

Sklivvz
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  • **Note**: this question was asked as part of the "[topic of the week](http://meta.skeptics.stackexchange.com/q/1371)" initiative to raise our questions per day stat. Please contribute some great questions! – Sklivvz Mar 18 '12 at 20:48

1 Answers1

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Sauna makes your heart work harder

Sauna definitely increases heart rate ([1] and [2])

Does sauna makes you burn calories the same as exercise ? No.

The most accurate method of measuring calorie burn is through VO2 testing ... Combustion, which turns the fuel you receive from food into energy, needs oxygen. Because there is a direct relationship between how much oxygen you use and how much energy you burn, by measuring the oxygen to carbon dioxide exchange through VO2 testing, you will get a fairly precise gauge of how many calories you're burning.

eHow "How Heart Rate Monitors Calculate Calories Burned"

This study has show following results:

VO2 on exercise (ml/min) 1269,4 +/- 426,1 VO2 on suana (ml/min) 236,9 +/- 42,7

Oxygen update in suana was much less then during exercise.

What about sauna and sitting ?

Let's say sitting requires 1 MET, then for 120 kg person would intake about 120 ml / min. Walking for the same person (120 kg) would be 120 kg * 3 ml / min kg = 360 ml / min

So, sauna makes your body burn more calories than sitting, it's can't be compared to exercises.

4erkas
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  • You lost me in the last part. Do you burn more calories than sitting? How many more? – Sklivvz Mar 24 '12 at 14:09
  • @Sklivvz **Sitting: ~120 ml/min, Sauna: ~240 ml/min,** Walking: ~360 ml/min, Exercise: ~1270 ml/min. Calorie burn depends on body statistics. – Ilari Kajaste Apr 04 '12 at 05:45
  • But it's quite possible the 120 ml/min increase in VO2 value doesn't do much for the calorie burn. I'm not familiar enough with the topic to do the calculations. There are [some online calculators](http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.aspx) for this type of stuff but it seems they don't take the values in the form provided in this answer. – Ilari Kajaste Apr 10 '12 at 05:50