How well do you know your sweat?

by Kim on September 3, 2013

If you’ve ever taken a hot yoga class, you’ve probably asked yourself this question: “Is the heat worth it?”

hot yoga(source)

Running in the heat is one thing—you can’t control the weather, and most of us can only tolerate the dreadmill for so long. But when you walk into a room where the thermometer is purposefully jacked up, you’re making a choice. You’re asking to be hot.

It’s easy to walk out of a hot yoga class feeling like you’ve just dominated the universe because your clothes are drenched with sweat, but did you really “earn” that sweat in the way your brain is telling you you did? (And the even deeper question: does it matter if it makes you feel good, psychologically?)

What if I told you that your body actually burns more calories heating itself (by shivering) than cooling itself (by sweating)? Now is it worth it? (Maybe there should be a cold-room workout on the market—imagine how much harder you’d work in a 35 degree room just to warm up!)

I asked myself all these questions in this post, and found some interesting research about the physical and psychological effects of hot yoga.

Today, I’m here with the follow-up: can you learn anything from how much you sweat? Or are we reading too much into this simple little cooling process?


Ever since I wrote that original post, I’ve been wanting to dig up some truth about the various sweat-related controversies, like sweating out your toxins and wearing sweatsuits to lose pounds, and also to find answers to random questions about sweat, like “why do I sweat like a pig in group classes while everyone else is gently glistening?”

Actually, let’s start there.

Why do pigs get such a bad rap for being sweaty?

(I know this is really weighing on you—stick with me, it’s actually pretty interesting!)

The problem is that most of us aren’t thinking of the right pigs. The pink, snouted kind actually have very ineffective sweat glands and rely mostly on good old mud to keep them cool.

The phrase “sweating like a pig” is allegedly derived from the iron smelting process. The traditional shape of the molds used for iron involved a branching structure that looked like this:

pig iron

You can see how it got the name "pig iron."

As the “pigs” cool in this mold, the surrounding air reaches its dew point, and beads of moisture form on the surface of the pigs. "Sweating like a pig" indicates that the pig has cooled enough to be safely moved. (a source)

Which brings me to the next burning question…

How does sweating actually cool you?

You might think it’s the fact that you have liquid on your skin that’s causing the cooling effect. But really, your skin isn’t actually cooled until the sweat evaporates off of it.

The evaporation rate depends on the temperature and humidity of the air, suggesting that the real reason sweat accumulates more on super humid days (and in those crazy Bikram yoga classes) is that it can’t evaporate fast enough. So it might just look like you’re sweating more when it’s more humid, because your sweat remains on your skin longer. (To make matters worse: a layer of sweat on your body acts as a sort of insulator, making you even hotter.)

If I sweat more than everyone else, does it mean I’m out of shape?

I think the best answer to this question is: it doesn’t necessarily mean anything.

Sure, overweight people sometimes sweat more profusely than average-weight people because fat acts as an insulator that raises core body temperature.

But heavy sweating is also often a sign of fitness, since fit people’s bodies have learned to cool more efficiently. “An athlete who has adapted to keep the body core cool during exercise will shunt blood to the skin’s surface more quickly and release heat from the body. At the same time, the sweat glands increase their output and thus cool the body during sweat evaporation. While fit people produce more sweat than sedentary folks, they lose less sodium, because more of it is reabsorbed by the body.” (source)

Fit people also sweat sooner during workouts, due to their cooling efficiency. So while an unfit person might heat up faster in response to exercise, it’ll take longer for his sweat system to kick in and cool him down.

Other things that affect sweat volume are gender (fit men sweat significantly more than fit women), number of sweat glands (women usually have more than men, but each gland produces less sweat than a man’s would), room temp/humidity, genetics, exercise intensity, and the person’s emotional anxiety level. (source)


Also, possibly the most important factor of all: people are just different, the same way they are with everything else.

Can you use sweat to gauge your intensity level?

You can probably guess the answer: not really.

You might be able to get some information by comparing how much you sweat during one activity to how much you sweat during another activity (all environmental factors equal). But how can you be sure that you weren’t just more dehydrated one of the times, so that your body was less comfortable letting go of fluid? Or maybe you were more stressed out, which can cause your core body temp to go up.

The gold standard in intensity gauging is still a heart rate test, or its less sophisticated brother, the “talk test.” (Can you hold a conversation while working out?)

Why do yoga instructors suggest NOT wiping off sweat?

Remember: sweat itself doesn’t cool you down. Only the evaporation of sweat does.

The more you wipe your sweat off, the harder your body has to work to produce more in hopes that it’ll have a chance to evaporate.

Yoga instructors will also say that it’s distracting to your practice. But if you have a brain like mine, a quick sweat swipe is the least of your worries.

20130816_092850That smile can only mean one thing: I’m about to fall.

Of course, sweat can be really annoying when it’s pouring down your face. I always wipe my forehead and around my eyes liberally—sorry, body, but deal with it.

(Speaking of what not to do: it’s also not a great idea to splash your face with cold water right after a workout, since the cold closes your pores, trapping in all the sweat that was on its way out.)

When you sweat, are you REALLY sweating out toxins?

Ok, here’s the money question. From what I’ve found, the answer is: maybe a teensy bit, but hardly enough to be considered a “benefit” of hot yoga.

According to this article (and several others): “In general, all sweat contains the same primary ingredients: mostly water, some sodium and chloride, and to a lesser extent, potassium. Though you do lose electrolytes when you sweat, perspiration contains only trace amounts of any type of toxins.”

Almost all of your body’s toxin-flushing work is done through the liver and kidneys (which, err, were designed for that purpose), to the point where any sweat-based detox plan is kind of laughable. It’s like opening a dam vs. poking a peep hole through it.

In fact, sweating for detox can actually do you more harm than good if it leaves you dehydrated, since your kidneys need plenty of water to do their job (aka the legit detox work). Which suggests that you could potentially veg out on your couch all night and end up more toxin-free than if you’d gone to hot yoga.


Does working out in sweats really help you lose more weight?

I think this myth is mostly dead, but I thought I should include it just to make sure.

Sure, wearing tons of heavy clothing helps you lose more weight—water weight, due to excessive sweating, which you’ll gain right back as soon as you’re hydrated again.

The Rocky-style work-out-in-thick-sweats routine is a remnant from sports with weight classes, like wrestling. The idea is that an athlete will put on extra muscle weight, then dehydrate himself right before an event or weigh-in to fit into a certain weight category. (In hopes that he’ll have a chance to re-hydrate before actually competing.)

If you’re trying to lose weight, you’re really trying to lose fat. Wearing tons of layers will just make your workout feel harder, potentially preventing you from working as hard as you could otherwise.

So let’s just stick to our skimpy shorts and ultra-thin tank tops in the gym, right ladies?? Ya floozies. (Kidding!)

Why does some people’s sweat stink worse than others’?

Actually, sweat itself doesn’t smell at all. Poor, innocent sweat gets such a bad rap.

It’s the bacteria that live on our skin and (grossness alert—SORRY!) feed on the sweat that give skin a stinky smell.

If you want to keep the stink level down, this article suggests avoiding sulfurous foods like meat, eggs, dairy, onions, and garlic before a workout. Coffee and alcohol can apparently also be responsible for stinkifying sweat. (I honestly never thought I’d use the word stinkifying in a blog post. Have I stooped too low?)

Phew. I’m seriously feeling a little overheated just writing all this. Also, I was pretty serious about that cold-room workout class idea…

Do you consider yourself a heavy or light sweater?

Do you find that some activities make you sweat more than others?

Does anyone else find this stuff interesting?

Sorry if I bored you!!


{ 23 comments… read them below or add one }

Mons January 17, 2017 at 9:10 pm

I think this was a great blog post. I go to hot yoga about 6 times per week, in addition I run between 15 and 25 miles per week. I have a resting heart rate of 54 and I sweat like a sea monster. I really couldn’t understand why I sweat so much, I believe I am in pretty good shape and yet I am always the first one soaked in yoga.
Reading your blog, there is something to the notion of my body getting ready to cool down sooner because it is so accustomed to the work out. I feel a little better about myself now…so thank you.


utes walsh January 2, 2016 at 10:44 pm

You’re not alone!! I love information about my body and being educated about health,its pur personal responsibility to research as much of the media is funded by someone trying to sell a product and obviously bias in its promotion. O find most health products and routine to be extremely deceptive on closer inspection.

There is nothing gross about sweat or bacteria,its all pwrfectlt designed to preserve our bodies health.

I read your blog because I’ve recently started hot yoga and I’m just gushing . I’m very active,so i drink about 3l of water a day as a norm.i dont drink anything else except 2 small coffees a day.

Everyone IS my case,even though I’m a woman,i have the muscle structure and building capacity of an above average male.i was born with a sixpack and defined muscles in my calves. I also have a very large skeleton for a female. It took me ages and finally professional testing to figure out the bmi system is just ridiculously unrealistic in my case.

Apart from that my body cannot metabolize cane sugar,alchohol or most refined starches,so i live on meats,fats,vegetables,fruits,seeds,nuts and dairy.once or twice a week i can have potato or gluten free grains,but then i need 3 days to digest. Ive known and lived this for 12 years.

In an average day,i speand at least 3 hrs being physically active.i live in beautiful melbourne,so i ride my bike everywhere (averaging 20-30km a day)i walk,swim,practice yoga,weight lift and do adventure sports (surfing,kayaking,body boarding,hiking,climbing etc)as much as i can. I started my life as being diagnosed as hyperactive,but it took a while to work out im just quite smart.i do excersize as a coping mechanism for PTSD and bipolar. I feel calm when i move.also,after some disasterous trials,i refuse to use chemical medication. It just dumbs you down and sedates you. I felt like a zombie and a shadow of myself and could no longer create or put my thoughts in words. Ao i medicate with stress relief,excersize (physical and mental) and food.

10 years ago i had a mc donalds burger for the first and last te and literally ended up in the emergency shut down.

So with all this background,why do you think it is that the water just flows out of my pores?i double towel in yoga and it just pours off me. I add rehydration capsules to the water i drink, so i dont get dehydrated. Id like to know if im unhealhy or if im just naturally a sweaty Betty in yoga class.i dont sweat that much in any other activity.

Thank yiu for the information and your lovely sense of humor.


Lindsey I August 4, 2014 at 10:13 pm

What a great post! I have always been a ridiculous sweater… to the point where I prefer to work out alone so no one can see the rain shower of sweat that comes off of me. Very interesting read! Thanks for sharing all that info! :)


Kim August 5, 2014 at 9:55 am

Glad you liked it! :)


Hadie August 4, 2014 at 11:53 am

Kim!! I loved this article – I know it’s been awhile since you posted it. This morning in Yoga – I noticed that I was sweating BEYOND what anyone else was…. I consider myself fit – lots of weight training and rowing per week…. I thought maybe it was my diet compared to most in the class look like vegetarians, etc …. me…? well I do Paleo – lots of protein…. I wonder if the protein plays a significant difference?


Kim August 4, 2014 at 2:49 pm

Thanks Hadie! I really don’t think the extra sweat means much of anything, other than that’s what your body likes to do. :) I certainly don’t think of it as a sign of lack of fitness–in many cases, it’s the exact opposite!

Thanks for stopping by and glad you liked the post! :)


Tina July 22, 2015 at 4:01 pm

I know this post is really old but I just wanted to add to your question that our bodies can’t completely burn down the Proteins so the energy that we can’t use actually heat us up a little bit. So in theory it could be your diet but I really don’t know how big of a difference it actually makes


Erika September 4, 2013 at 2:09 pm

Great post! Just last week it was like 100 degrees out and I was at a garage sale with sweat just running down my back and I thought “I’m not even doing anything!” – so it just goes to show that sweat is sweat and not necessarily a measure of how hard you are working or calories you are burning. I have also read long ago that you burn more calories drinking ice cold water vs. warm/hot water because your body has to work harder to warm it up. It really all makes sense you think about it. You answered a lot of great questions and taught me a few things about sweat! BTW I totally stink worse depending on what I eat but I’ve also noticed that I stink worse since having a baby (2 years ago!).


Amanda N September 4, 2013 at 6:38 am

First time visiting your blog and I love this post. Very interesting! I’m a heavy sweater as is my husband although he is worse than I am.


Kim September 4, 2013 at 6:44 am

Thanks for stopping by, Amanda! Glad you liked the post. My husband definitely out-sweats me too. :)


Giselle@myhealthyhappyhome September 3, 2013 at 10:58 pm

I use the phrase, “I sweat like a pig” so frequently! I really do sweat a lot and it’s interesting to hear some possible reasons why. I definitely used to think that if I didn’t get a good sweat then I wasn’t getting a good workout. Thankfully that thought process has changed!
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Kate September 3, 2013 at 9:14 pm

I am definitely a heavy sweater! And I like the mental boost that I am “working hard” LOL
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Kim September 4, 2013 at 6:45 am

Totally, I don’t blame you!


Presley @ Run Pretty September 3, 2013 at 7:33 pm

I sweat profusely just from walking out of the door in the summertime. I definitely sweat a lot more than “average”… haha I am disgusting. If I’m not sweating A TON during a workout, I assume I’m totally dehydrated. Is that science? I don’t know.
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Kim September 3, 2013 at 9:09 pm

Pure science! You probably have a rocking metabolism too, lucky duck! :)


Kim September 3, 2013 at 7:12 pm

Loved this sweat-filled post!!
I’m a big sweater – I gross my husband out after some of my runs when I wring my sports bra out!!!
The funny thing about one of your comments (fit people often sweat sooner due to their cooling efficiency) – when Chris & I were first dating, he told me he knew he was in good shape because he didn’t sweat while running 3 miles! (then I made him run with me!!!) Now that we have been married 17.5 years, I will just keep your little research tidbit to myself!!! (and smile inside!!)
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Kim September 3, 2013 at 9:05 pm

Hahaha! What a good wife, I’d totally tell him. :)


Rebecca @ Strength and Sunshine September 3, 2013 at 7:08 pm

I rarely sweat! But sometimes (mostly in the winter) if I am working out when my body does try to sweat I get red welts all over my arms and legs. I am pretty much allergic to my own body trying to sweat haha!
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Kim September 3, 2013 at 9:08 pm

Interesting!! I know there are a few medical conditions that prevent people from sweating…I kinda skipped over that info because I wasn’t sure it would apply to anyone.

Sometimes I’ll just get the beet-red-face situation going on instead of actually breaking into a sweat…that’s always pretty cute. :)


Holly @ EatGreatBEGreat September 3, 2013 at 6:32 pm

This was such an interesting post to read! I, unfortunately, am a heavy sweater, and Zumba definitely makes me sweat like crazy!
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Kim September 3, 2013 at 9:04 pm

Sounds like you must be uber fit! :)


Ashley @ My Food N Fitness Diaries September 3, 2013 at 6:23 pm

Wow! SUPER interesting! You’re amazing for researching all of this! Thanks for sharing it with us. :)
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Kim September 3, 2013 at 9:03 pm

Phew, what a relief to hear that I’m not the only one who finds this stuff interesting! I was seriously worried that I was boring everyone to tears, but I just couldn’t rein in the nerdiness. :)


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