The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Sauna Suits: Your key to weight loss?

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Move more

Thursday, Jun 28, 2012

It is that time of year again—HOT! At least it is here in Texas. It reached 100 degrees this weekend! I couldn’t believe that while I was out and about I saw not one but TWO people (in different locations) wearing sauna suits while exercising. I was stunned not to mention concerned. Exercising in this heat by itself is a concern for some but add in exercising while wearing a sauna suit in this heat and alarms were ringing. In case you are unfamiliar, sauna suits are made from waterproof material and are designed so that the body retains heat and moisture causing the wearer to sweat profusely. They were created to imitate the effects of a sauna like you would find at a spa but many people use these suits for accelerated weight loss during exercise. Indeed profuse sweating will lead to the loss of pounds but from the loss of water not from the loss of fat.

Here’s what happens. Sauna suits contribute to weight loss by interfering with the body’s cooling system. You see the body functions at its best at an internal temperature of approximately 98.6 degrees and works hard to maintain this temperature. When our body temperature rises above this, there are several cooling systems in place, the most significant of which is sweat or more precisely, the evaporation of sweat. Sweat rate varies depending on many factors including the internal production of heat, the environmental temperature, humidity, the type of clothing worn, as well as others. Exercise raises the internal production of heat so our sweating rate increases in order to help cool the body. When a sauna suit is worn, however, the sweat cannot evaporate; therefore cooling does not take place. This leads to an even greater rise in body temperature and even more sweating as the body continues to attempt to cool itself. And the cycle continues—further rise in temperature, more sweating, further rise in temperature, more sweating. A significant amount of fluid is lost and results in temporary (I stress temporary) weight loss due to dehydration. For most individuals, when they rehydrate themselves, the weight returns.

So if the weight returns once rehydrated, what’s the big deal? Why was I so concerned? In this specific instance, you have exercise which raises body temperature, you have the inhibition of the evaporation of sweat (no cooling) because of the sauna suit, and you have the extreme environmental heat—a triple whammy. This very easily can lead to heat stroke which if not treated can cause damage to your brain, heart, kidneys and muscles. There are several cases where the use of sauna suits while performing intense exercise has lead to death. Even if heat stroke isn’t experienced, dehydration itself can have negative effects such as cramping, dizziness, confusion, loss of consciousness, and others. So even if these exercisers weren’t in the extreme heat they still should not be using a sauna suit during exercise.

So unfortunately, no. Wearing a sauna suit during exercise will not accelerate your weight loss efforts and in actuality is quite dangerous. Heck if sweating were the key to weight loss, everyone here in Texas (or living in extreme heat for that matter) would be skinny! Weight loss happens from eating better/less and moving more. Find what physical activity you enjoy, do it consistently, and leave the sauna suit behind.

1  U.S. Department of Health and Human Services; National Institutes of Health; National Heart, Lung, and Blood Institute. (2006). Your guide to physical activity and your heart (NIH Publication No. 06-5714). Retrieved from website: