Why Sweating a Lot Doesn’t Mean an Effective Workout
Let me introduce you to your trusty friend—sweat. Take a moment to forget the unpleasant sensation and potential odor of sweat and consider what it does to you: when your body overheats, threatening to raise your core temperature above normal, tiny glands in your skin squeeze droplets of moisture onto its surface. As soon as a gentle breeze touches these droplets, they evaporate, taking some of your body heat with them.
This is true even during exercise. It’s not the exercise itself that makes you sweat; exercise simply raises your body temperature, and it’s the heat that makes you sweat. That’s why you sweat without working out on a hot day, and why you can sometimes work out without sweating in a cold environment. In other words, sweat matters a lot less than you think. Sweating doesn’t mean you’re working out well, it doesn’t mean you’re losing weight, and it says little about your fitness level. Let me explain.
You can get a great workout even if you barely sweat.
At the same ambient temperature, more intense exercise can lead to an increase in body temperature, which is why we associate sweating with intense exercise. However, this is misleading.
If you go for an hour-long run in the heat, you’ll sweat profusely. Running on a treadmill for an hour at room temperature might not cause as much sweating, but you’ll still be damp. However, if you run for an hour in the winter, you’ll be almost completely dry. That’s because your body doesn’t have to worry about cooling down.
Besides ambient temperature, there’s another factor: not all workouts raise body temperature equally. An intense strength workout with plenty of rest may not raise your body temperature enough to cause you to sweat profusely. But that doesn’t make it any less intense than, say, a light jog. So, don’t overemphasize the amount of sweat you produce.
Why do some people sweat more than others?
One of the main differences between people who sweat a lot and those who sweat less is body size. And by “size,” I mean exactly that—it doesn’t matter whether you’re fat, muscular, tall, or somewhere in between. The bigger you are, the more effort your skin has to work to cool itself, and therefore, the more you sweat.
There’s also the surface area-to-volume ratio. The more skin you have relative to your body size, the more effectively sweat cools the body. This means that smaller people, including children, have a higher surface area-to-volume ratio, so they can cool themselves with less sweat. If you lose a significant amount of weight, you may sweat (slightly) less for these reasons. Your body mass will decrease, and your surface area-to-volume ratio will improve slightly.
On the other hand, the fitter you are, the more you may sweat, as studies show that runners’ sweat glands activate earlier than sedentary people, and they sweat more during the same workout. Therefore, increased sweating doesn’t mean you’re out of shape; in fact, it may indicate you’re more physically prepared and better adapted to the heat than people who sweat less.
Finally, if you think you’re the sweatiest in your group of friends, consider how valid your comparisons are. If you’re drenched in sweat while running in the midday sun, while your friend is posting selfies from the air-conditioned gym, don’t expect them to sweat the same.
What is the connection between sweating and weight loss?
Sweating profusely during a workout doesn’t necessarily mean fat loss, so let’s dispel that myth. However, profuse sweating can lead to water loss, which is only temporary.
Our blood, cells, and various components of our body contain a certain amount of water. We can lose a small amount of water, becoming mildly dehydrated, and barely notice. Or we can drink a huge amount of water, become severely dehydrated, and need to urinate frequently to restore normal fluid levels. In extreme cases, dehydration can be so severe that it poses a health risk, but this is rare during normal activity.
When you sweat, and that sweat evaporates or washes off (for example, when you wipe your forehead with a towel), it means water is leaving your body. You can weigh yourself before and after a workout and notice a change in weight if you’re sweating enough. Every kilogram you lose represents two cups (16 ounces) of water leaving your body. So technically, you’ve “lost weight,” but it’s not fat. You just need to drink two cups of water, and then you’ll be hydrated and happy again.