Sweating cools us down, but does it burn calories?

While some people endeavor to prevent, hide, or cover up sweating, it's really nothing to be ashamed of and nothing that can (nor should be) stopped. Research shows that humans have between 2 and 4 million sweat glands within our bodies - each connected to the surface of our skin via coiled tubes called ducts. 

Though sweating is almost always a good thing, so long as we're replenishing the lost liquid by drinking plenty of water, "there are times when the body's mechanism that contributes to sweating may be malfunctioning or receiving incorrect signals such as during menopause, which contributes to sweating associated with hot flashes," says Jewel Kling, MD, Assistant Director of Women's Health for Mayo Clinic. There are also times when sweating may be associated with anxiety or certain medical conditions.

But the benefits of sweating are many, and experts say it's an important bodily function that we should be glad our bodies have. 

What's in sweat? 

Though sweat contains trace amounts of electrolytes such as potassium, chloride, sodium, ammonia, calcium and magnesium, it's 99% water. We sweat up to a quart of liquid each day, with much of it evaporating without our noticing. Replenishing is one of the reasons it's recommended for men to drink a little over 3 quarts of water a day and for women to drink a little over 2 quarts daily. 

Sweat also often contains bacteria which can grow in one's released sweat and contributes to the unpleasant odor sweat is known for. People often seek to mask the smell of body odor with fresh scents, natural products such as coconut oil or apple cider vinegar. More commonly, people use deodorant. Though some deodorant is advertised as "all natural," (meaning it only masks smells), deodorant marked as "antiperspirant," is deodorant that contains aluminum, which both masks sweat's odor and blocks sweat from flowing to the surface of the skin where its applied. 

What are the benefits of sweating? 

Sweating has several health benefits such as being a good natural skin moisturizer, helping to improve circulation, and being associated with the release of feel-good chemicals like endorphins. 

But sweat's most important function is that "it keeps our bodies from overheating," says King. Indeed, temperature regulation is essential − especially when one is in warmer climates or engaged in activity. "As soon as our body’s internal temperatures start rising, our brains tell our sweat glands that it’s time to start cooling the body down by producing sweat," explains Emily Skye, a certified personal trainer and founder of Emily Skye FIT.

Beyond keeping our bodies cool, some people also believe we release toxins when we sweat, though that claim is mostly exaggerated. While it's true that sweating can get rid of very minimal amounts of heavy metals such as nickel, copper and mercury, it's actually the kidneys and liver that handle most of the body's detoxification needs, not sweat glands. 

Does sweating burn calories?

Another misconception about perspiration is that sweating burn calories. The short answer is that sweating is not associated with burning calories because it only does so very marginally. "Sweating itself burns only a very small number of calories," explains Anthony Beutler, MD, an associate medical director of sports medicine at Intermountain Health in Salt Lake City. He says this negligible number of calories burned occurs because sweating requires the body to fire small muscle fibers that expel sweat from sweat glands. "But typically, the physical exercise that leads to sweating burns far more calories than the actual ‘work' of sweating," he says. 

Indeed, even though sweat doesn't equal calories burned, sweating is often a great indicator that one is expelling energy. "Sweat itself isn’t a measure of how much energy you’re burning nor how effective your workout is, but in most situations where you’re sweating a lot, you’re also usually burning energy," explains Kayla Itsines, a certified personal trainer, fitness author and co-founder of the popular fitness app, SWEAT.

That means that when one is engaging in cardio, Pilates or bodybuilding, one is burning calories − regardless of the amount one sweats in the process.

It also means that spending extra time in the sauna or participating in thermal exercises like hot yoga may not help you lose more than water weight. "These workouts definitely have benefits, as hot workouts warm the muscles up faster which help to improve flexibility, reduces stress and increases lung capacity," explains Skye. "However, the extra sweat does not mean more calories have been burnt."