# Sweating off pounds? **URL:** \ **Category:** Factual Questions\ **Created:** [April 12, 2005, 2:59pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969 "2005-04-12T14:59:03Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [April 12, 2005, 2:59pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/1 "2005-04-12T14:59:03Z")
It’s getting pretty warm down here in SW FLA and sweating season has started. I’m wondering how many calories does one lose from sweating? I know that one loses temporarily loses weight from the water leaving the body. But that is regained simply by drinking more water. Does the process of sweating burn calories, or does getting overheated ramp up the metabolism and burn more energy? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [April 12, 2005, 3:14pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/2 "2005-04-12T15:14:23Z")
I don’t know the answer to your question. As you pointed out though, sweating is ‘water weight’; not Calories. When you sweat, you need to drink water to rehydrate. I’ve heard that you burn more energy at lower temperatures, say, 40°F, because your body is generating more heat to keep itself warm. ---
**Author:** ![velvetjones](https://avatars.discourse-cdn.com/v4/letter/v/5f9b8f/32.png) [@velvetjones](https://boards.straightdope.com/u/velvetjones)\ **Post date:** [April 12, 2005, 3:17pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/3 "2005-04-12T15:17:40Z")
Wish I could find a cite for this. I once read that swimming was not as efficient for weight loss precicely because the temperature of the water keeps your body from heating up and you end up not burning as many calories because your body isn’t expending any extra energy to stay cool. True, you burn more calories at rest trying to stay warm when it’s cool but I don’t think that principle applies here. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [April 12, 2005, 3:27pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/4 "2005-04-12T15:27:37Z")
> [@velvetjones](#): > > I once read that swimming was not as efficient for weight loss precicely because the temperature of the water keeps your body from heating up and you end up not burning as many calories because your body isn’t expending any extra energy to stay cool. Nah, the problem with swimming is that exercising in cool water will jack your appetite up like nothing else. You can lose weight just fine by swimming as long as you can resist the temptation to eat a whole horse afterwards. ---
**Author:** ![Boldface\_Type](https://avatars.discourse-cdn.com/v4/letter/b/b5e925/32.png) [@Boldface\_Type](https://boards.straightdope.com/u/Boldface_Type)\ **Post date:** [April 12, 2005, 3:34pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/5 "2005-04-12T15:34:14Z")
> [@Johnny L.A.](#): > > I’ve heard that you burn more energy at lower temperatures, say, 40°F, because your body is generating more heat to keep itself warm. Although when exercising you will burn less energy at a given work rate when the ambient temperature is relatively low versus relatively high. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [April 12, 2005, 3:37pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/6 "2005-04-12T15:37:19Z")
> [@Boldface Type](#): > > Although when exercising you will burn less energy at a given work rate when the ambient temperature is relatively low versus relatively high. What sort of difference are we talking about? Is it physically significant? ---
**Author:** ![tremorviolet](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)\ **Post date:** [April 12, 2005, 4:01pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/7 "2005-04-12T16:01:43Z")
> [@ultrafilter](#): > > What sort of difference are we talking about? Is it physically significant? Hmmm, well this [Merck Manual cite](http://www.merck.com/mmhe/sec01/ch006/ch006e.html) says: > [@](#): > > If weight loss is one of the main goals of exercise, however, swimming is not the best choice. Exercise out of water is more effective because air insulates the body, increasing body temperature and metabolism for up to 18 hours. This process burns extra calories after exercise as well as during exercise. In contrast, water conducts heat away from the body, so that body temperature does not rise and metabolism does not remain increased after swimming. So it would make sense that exercising in cooler air also affects your body temperature. I always thought you burned _more_ calories when it’s cold because you’re expending more calories through shivering to keep warm. But that probably only applies to an “at rest” state. Wait, I just found an entire [article](http://www.kaizenhealth.com/pages/acoldweather.htm) about this. This passage is interesting (although there aren’t any cites): > [@](#): > > Skin temperature also affects growth hormone levels. In fact, simply taking a hot (38-39 degrees Celsius) bath for 25 minutes will raise growth hormone levels more than ten-fold. > > A single surge in growth hormone increases both the number of fat calories your body burns for energy and your metabolic rate. That’s why growth hormone therapy often leads to a reduction in fat mass. Hmmmmm, maybe I should write a book called “The Bath Diet”… ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [April 12, 2005, 4:06pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/8 "2005-04-12T16:06:20Z")
> [@tremorviolet](#): > > Hmmm, well this [Merck Manual cite](http://www.merck.com/mmhe/sec01/ch006/ch006e.html) says: > > > [@](#): > > > > If weight loss is one of the main goals of exercise, however, swimming is not the best choice. Exercise out of water is more effective because air insulates the body, increasing body temperature and metabolism for up to 18 hours. This process burns extra calories after exercise as well as during exercise. In contrast, water conducts heat away from the body, so that body temperature does not rise and metabolism does not remain increased after swimming. It’s still not quantified, though, so we don’t have any idea whether we’re talking 5 or 50 calories per session. If it’s the latter, it might be worth taking into account, but if it’s the former, why worry? And pretty much anything you do will raise growth hormone. If you want a real spike, skip breakfast and drop a 45 lb. plate on your foot. ---
**Author:** ![tremorviolet](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)\ **Post date:** [April 12, 2005, 4:37pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/9 "2005-04-12T16:37:52Z")
> [@ultrafilter](#): > > And pretty much anything you do will raise growth hormone. If you want a real spike, skip breakfast and drop a 45 lb. plate on your foot. We could call it the “Masochist’s Diet” and make millions. 😉 ---
**Author:** ![Boldface\_Type](https://avatars.discourse-cdn.com/v4/letter/b/b5e925/32.png) [@Boldface\_Type](https://boards.straightdope.com/u/Boldface_Type)\ **Post date:** [April 12, 2005, 6:06pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/10 "2005-04-12T18:06:31Z")
> [@ultrafilter](#): > > What sort of difference are we talking about? Is it physically significant? Absolutely; pretty much all endurance event worlds records are set in cooler temperatures because of this (and related factors). Basically less energy needs to be expended in the mechanisms that cool the body, or otherwise respond to heat stress when ambient is cool. (Plus, of course, in cooler temperatures athletes are less liable to suffer from hyperthermia). I don’t know if the difference in energy expenditure between exercising in cool versus warm temperatures has been quantified as such. When exercising in the heat, VO[sub]2[/sub] max is reduced by several percent (e.g., Sigurbjorn et al, 2004; [DOI: 10.1007/s00421-004-1053-1](http://dx.doi.org/10.1007/s00421-004-1053-1) ), probably due to factors such as vasodilation and the consequent increase in how hard the heart needs to work at a given speed, and in increased sympathetic nervous system activity. That’s some sort of quantification. Also, for runners exercising at 35degC versus 15degC (8k performance run), heart rate was increased by a few % (Marino et al., 2001; [DOI: 10.1007/s004210100506](http://dx.doi.org/10.1007/s004210100506)). Performance reduced by a greater percentage. I guess it’s reasonable to say that the energy cost of running a given pace is increased by a few % in warm versus cool conditions. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [April 12, 2005, 6:22pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/11 "2005-04-12T18:22:30Z")
> [@tremorviolet](#): > > Hmmmmm, maybe I should write a book called “The Bath Diet”… Hmmmmmm, maybe I should go sit in the hot tub for a while… ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [April 12, 2005, 8:33pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/12 "2005-04-12T20:33:23Z")
Now I won’t feel so bad about taking a walk in the heat of summer. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 12, 2005, 9:28pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/13 "2005-04-12T21:28:17Z")
> [@tremorviolet](#): > > Hmmm, well this [Merck Manual cite](http://www.merck.com/mmhe/sec01/ch006/ch006e.html) says: > > > [@](#): > > > > If weight loss is one of the main goals of exercise, however, swimming is not the best choice. Exercise out of water is more effective because air insulates the body, increasing body temperature and metabolism for up to 18 hours. This process burns extra calories after exercise as well as during exercise. In contrast, water conducts heat away from the body, so that body temperature does not rise and metabolism does not remain increased after swimming. > > So it would make sense that exercising in cooler air also affects your body temperature. Hmmm…I hate to argue with the Merck Manual, but when I was swimming one to two miles three times a week I lost weight like crazy, as opposed to running 5-6 miles a day (5-6 times a week), where I plateaued out quickly and stopped losing any weight, even after switching routes to climb that monster-friggen hill on Lincoln Dr (Milwaukee) 3-4 times in rapid succession. I also felt the after-exercize whole body “buzz” from swimming for the rest of the day (if I went at lunch), whereas my effects from running disappear after an hour. On the other hand, as **ultrafilter** points out, swimming makes you want to eat, eat, eat. I couldn’t choke down enough fruit and carbs to satisfy my bodies continued need for energy and ended up eating a couple of granola bars and a cup of yoghurt (if I remembered to pack lunch) or couple of Snickers (if I didn’t), and _still_ I was famished when I got home from work. Yeah, Nikos down at **Apollo** got to know me real well that year. “My friend! You want-a the special gyro, or-a the beef souvlaki? You want-a the avgolemono too, no? Ah, let-a me throw in some spanakopita. You want-a some baklava, no? Ah, my friend, come back soon!” And I still lost weight. Now I can’t lose ten pounds by eating rice and salad. :rolleyes: I’ve got to start trailrunning. Stranger ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [April 13, 2005, 12:36am UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/14 "2005-04-13T00:36:40Z")
Decades ago, a neighbor and I both were home with our respective infants and wanted to lose weight and tone up. We opted for swimming at the local YWCA. Negatory on the weight loss, but lots of improvement in stamina and muscle tone. We were doing some significant swimming, too, and got up to being able to swim 1/4 mile without stopping. To lose weight for real, we took up bicycling. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 13, 2005, 12:52am UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/15 "2005-04-13T00:52:15Z")
> [@MLS](#): > > Decades ago, a neighbor and I both were home with our respective infants and wanted to lose weight and tone up. We opted for swimming at the local YWCA. Negatory on the weight loss, but lots of improvement in stamina and muscle tone. Maybe the problem with swimming is that people tend to limit their speed to what feels comfortable, which may be a good low-intensity workout but doesn’t really get the heart rate up. I _hate_ rotation lane swimming because I’m always outpacing other swimmers, except for the hardcore people with the shaved eyebrows and six-pack abs. (Note: that ain’t me, even when I was swimming regularly.) Pushing, I can (or could) do a mile in about 24 minutes, and 2 miles in slightly under an hour, which doesn’t seem (to me) to be all that fast, but it is a good workout. Going much slower than that probably isn’t going to give you as much effect. The people doing a slow backstroke for hour, or bouncing up and down the lane in the shallow end? I don’t see how that’s doing much of anything at all, aerobically. Stranger ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [April 13, 2005, 1:18am UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/16 "2005-04-13T01:18:44Z")
No, we were doing vigorous and exhausting exercise, not just a lazy backstroke. But we wouldn’t have had time for a two-mile swim! We had babies waiting in the child care area, so we only had about an hour altogether to change, swim and change again. ---
**Author:** ![threemae](https://avatars.discourse-cdn.com/v4/letter/t/5f9b8f/32.png) [@threemae](https://boards.straightdope.com/u/threemae)\ **Post date:** [April 13, 2005, 2:23am UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/17 "2005-04-13T02:23:43Z")
In my Biochem class, my prof said that a full _25%_ of your basal metabolism is used up by Na+/K+ transporters, basically the ones involved in maintaining the typical cellular membrane potential. That’s around 4-500 calories per day for most people. Also, I’ll admit that I don’t know the exact mechanism for how your sweat glands work, but I’m guessing that it involves pumping molecules against their gradient to create a hypertonic solution on the outside to leach water out of your body, so the amount of calories used in sweating may be significant. Will it offset the fact that you feel more tired and are likely not working as intensely in the heat? What if you have to add a shower because of the heat when you could have made it without one in a cooler workout temperature? Will that take 20 minutes away from your workout? I think that sweating itself might be a significant calorie sink, but I don’t know if it offsets the discomfort of exercising in a warmer environment. ---
**Author:** ![Valgard](https://avatars.discourse-cdn.com/v4/letter/v/7feea3/32.png) [@Valgard](https://boards.straightdope.com/u/Valgard)\ **Post date:** [April 13, 2005, 4:25am UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/18 "2005-04-13T04:25:02Z")
> [@tremorviolet](#): > > We could call it the “Masochist’s Diet” and make millions. 😉 And just think of your ad - “I dropped 45 pounds this morning!” ---
**Author:** ![Boldface\_Type](https://avatars.discourse-cdn.com/v4/letter/b/b5e925/32.png) [@Boldface\_Type](https://boards.straightdope.com/u/Boldface_Type)\ **Post date:** [April 13, 2005, 3:40pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/19 "2005-04-13T15:40:39Z")
> [@threemae](#): > > Will it offset the fact that you feel more tired and are likely not working as intensely in the heat? What if you have to add a shower because of the heat when you could have made it without one in a cooler workout temperature? Will that take 20 minutes away from your workout? > > I think that sweating itself might be a significant calorie sink, but I don’t know if it offsets the discomfort of exercising in a warmer environment. Well, the point I was making was: If you are working at the same rate (e.g., a set pace if running, cycling, whatever) then you will be using more kcal in warmer conditions. However, the point you make is a good 'un: If you work at a set perceived effort, then you may indeed use fewer kcal per unit time in hot weather. And surely everyone will shower after a proper wokout, cold or not? ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [April 13, 2005, 5:14pm UTC](https://boards.straightdope.com/t/sweating-off-pounds/298969/20 "2005-04-13T17:14:09Z")
Mor to the point, that Merck manual totally forgets the water resistance.Sure, it’s partially bouyant, but swimming takes a lot more out of you pushing through the water than running does. [Next page](https://boards.straightdope.com/t/sweating-off-pounds/298969.md?page=2)