There are times (think: indoor spin classes, indoor training sessions, or really hot really long rides) where we just pour sweat. We can ride every day and feel fairly fit, yet in certain circumstances, we’re drenched. People have been correlating sweat and calorie burn for decades, but can you actually tell how good of a workout you got based on sweat alone—does sweating burn calories?

We spoke to Bryan Saltzman, M.D., a Charlotte, North Carolina-based sports medicine physician, and Natasha Trentacosta, M.D., a Los Angeles-based sports medicine specialist, to find out if sweating actually burns calories, why some people seem to perspire way more than others, and what your sweat stains (or lack thereof) say about your workout.

Get Bicycling All Access for the latest cycling and health tips!

Here’s a real quick recap of sweat’s actual purpose: Those little droplets are your body’s way of regulating your body temperature when things heat up, which happens when you put your muscles to work during exercise.

“Our sweat glands produce a water-rich secretion onto our skin’s surface,” says Saltzman. When the sweat evaporates off your skin, the result is a natural cooling effect, which in turn helps to keep your core temperature from getting too high, he explains.

It’s true, though, that some people seem to be a lot sweatier than others. “Not all people sweat the same doing the same activity,” says Trentacosta. Yes, your fitness level plays a role—the better shape you’re in, the more efficient your body becomes at regulating temperature, says Saltzman, thus the more you might sweat. But there are other factors at play. Men generally perspire more than women, and heavier people tend to sweat more than those who weigh less.

Still, it’s possible for two people of the same sex, size, and fitness level to sweat differently. Genetics play a part in sweating, so the sweatier person might have more sweat glands than their drier counterpart.

“Furthermore, the physiologic response of individuals’ thermoregulatory autonomic nervous systems are just inherently different and react differently to temperature and exercise,” Saltzman says. In other words, the way your body handles changes in temp might just be different from someone else’s.

External factors play an important role, too. The weather conditions such as heat and humidity often make the biggest impact on your sweat rate. Consuming alcohol or caffeine before a workout can make you sweat more, Trentacosta notes. Then there are your clothes: Heavier garments or those made from synthetic materials (like polyester) trap more heat and result in more perspiration than lighter ones or those made from natural fibers (such as cotton or wool).

Okay, but what about calories—can sweaty exercise help you lose weight faster? A more intense workout will burn more calories than a less intense one. But remember, heavy sweating isn’t necessarily an indication that you’re exercising harder. Take, for example, a hot yoga class, in which yoga is practiced in heated rooms. The activity itself (yoga) is quite gentle and low intensity, but you may leave drenched in sweat due to the heat and humidity of the room.

This content is imported from poll. You may be able to find the same content in another format, or you may be able to find more information, at their web site.

The key here is to recognize that sweat loss is more representative of water loss than fat loss. Just because the scale reads a little lower after a sweaty ride doesn’t actually mean you burned off lots of fat. “Those pounds are just water weight that will often restore itself once you rehydrate,” Trentacosta says.

That’s not to say you haven’t burned any fat during the workout. You had to burn both carbohydrate and fat calories for energy. But the sweat is not a good measurement of that.

Research backs this up. In a University of Wisconsin-LaCrosse study, scientists had healthy, fit subjects participate in an hour-long yoga class in a 70-degree room. The next day the subjects did the yoga class again, but this time, the room temperature was cranked up to 92 degrees. Unsurprisingly, the subjects sweated a lot more and reported feeling like they were working harder when the room was warmer. But their heart rates were the same in both classes, suggesting that the subjects’ bodies were reacting the same way to the amount of work being done despite the amount of sweat.

There are many different variables that go into how sweaty or dry you are during exercise. Sweating more doesn’t necessarily mean you’re getting a better workout—and not sweating much at all doesn’t necessarily mean you’re cruising along on an easy spin. Yes, those droplets are an indication that your muscles are active and are generating enough heat to cause your core temperature to rise. But “simply sweating more doesn’t always correlate with working harder,” Saltzman explains.

The bottom line: Your sweat rate doesn’t dictate the quality of your workout. You could sweat profusely and not have burned a lot of calories or fat, or you could be mostly dry and have burned a lot of calories or fat. Your fitness level, genetics, alcohol or caffeine consumption, the environment, and what you’re wearing all play a role in how much—or how little—you sweat during exercise.

Want to get your sweat on? Here are a few indoor workouts you can do to boost your fitness:

preview for Fitness Episodes

Headshot of Marygrace Taylor
Marygrace Taylor
Marygrace Taylor is a health and wellness writer for Prevention, Parade, Women’s Health, Redbook, and others. She’s also the co-author of Prevention’s Eat Clean, Stay Lean: The Diet and Prevention’s Mediterranean Kitchen. Visit her at