No matter how good your antiperspirant is or how lightweight your workout clothes are, sweating while you work out is just about as inevitable as death, taxes, and splitting at least three pairs of undies while squatting. (Don’t pretend it hasn’t happened, buddy.) Ask most trainers or athletes, and they’ll tell you they know they’re…

Ask most trainers or athletes, and they’ll tell you they know they’re getting warmed up once those first beads of sweat start rolling.

But what even is sweat, and why do some people seem to take forever to start while others can hardly get from the gym parking lot to the locker room without doing it?

We tapped Lindsay Baker, Ph.D., Senior Principal Scientist at the Gatorade Sports Science Institute (GSSI), to find out. She specializes in sweat as it relates to athletes and how they can best hydrate to optimize their performance. Whether you’re a pro or not, knowing why you sweat and how it helps keep you safe is key if you want to push your limits during workouts.

Here are six interesting things you may have been wondering— or have never even considered— about sweating.

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What even is sweat? Is it “gross”?

Generally, sweat isn’t something that most people find appealing. It’s got a reputation for being “gross,” but sweat in itself isn’t made up of anything dirty.

“The main constituent of sweat is sodium chloride. So, you know, just like the bowl table salt, and that’s why it kind of tastes salty if you get it on your lips,” Baker explains.

Depending on the rate at which you sweat and how long you work out for, sodium chloride can be lost in high quantities and needs to be replaced, which is what sports drinks are for—but more on that later.

“Other things in sweat, like calcium, magnesium, or other minerals like that, are lost in much smaller amounts,” Baker says. “The main ones that we focus on when we’re working with athletes and giving them advice on electrolyte replacement before, during and after exercise are sodium and chloride.

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What determines how much someone sweats?

Some people are super sweaty, and some people barely break a sweat during a 5k or hitting a squat max. So, what gives?

It all goes back to the entire reason we sweat in the first place: to regulate body temperature.

“Even if they’re in the same room and doing a similar workout, athletes will generate different amounts of heat and therefore, the need for the body to sweat—to dissipate that heat through evaporation— varies,” Baker explains.

There are plenty of factors that determine the need to sweat. Baker cites exercise intensity, body size, and environmental conditions as three big ones. More intense exercise means muscles are working harder, which means more sweat. Larger individuals also produce more sweat than smaller individuals, and we all know a hotter environment leads to increased sweating. In the end, it’s all for the body to keep itself at a safe temperature.

The amount you typically sweat can also change as your body adapts to certain environments.

“The more heat acclimated you are, your body develops sort of like an adaptation to better thermoregulate,” Baker says. So if you’re really fit and accustomed to working out in the heat, you will start sweating sooner and you will sweat more so that you can do it while keeping your body core temperature in a safe zone.”

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Can I figure out how much I sweat? And does it matter?

Anyone can (and should) figure out how much they sweat during any particular workout. Fortunately, you can do so at home or even the gym fairly easily.

“Before a typical workout, measure your body weight nude or in minimal clothing, and then do your workout. After your workout, weigh yourself again in the same clothing,” Baker suggests. “In that 45 minutes, maybe up to 90 minutes, the weight loss that happens is mostly due to sweating.”

This simple experiment will give you a baseline for how much you actually sweat. Then, you can tailor your hydration to make sure you’re meeting your body’s needs.

“I think it’s important that people try to do that,” Baker says. “It’s really simple and practical to do, and that way they know about how much sweat they’re losing. That helps them understand how much they need to drink to avoid dehydration and the negative effects of dehydration during their workout.”

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Can I prevent myself from sweating so much?

While sweat is clearly a necessary part of safe exercise, many wish they could do without it. Some even go so far as getting Botox injections to stop their armpits or palms from excessively sweating. But again, your body sweats for a reason—to regulate temperature.

“Sweating is a good thing. So I think that’s something that people need to understand in the first place,” Baker says. “And you shouldn’t try to do things to avoid sweating. Evaporation of that sweat off the skin is so important to being able to safely participate in exercise in the heat.”

And even if you wanted to, there’s really no feasible way to decrease your sweating rate. Basically, you just have to accept that it’s a good thing that means your body is functioning properly.

“I think people need to realize that sweating serves a very important purpose,” Baker says.

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What is a “salty sweater”?

A salty sweater is someone whose sweat has a high concentration of sodium chloride, meaning they need to replace more electrolytes during exercise than someone who isn’t a salty sweater.

It’s important for athletes especially to know if they’re one of those people, because then they can be provided personalized hydration guidance. It’s something that would be good for anyone to know, but the catch is that the only way to tell would be having a sweat test done by a lab.

“Whether you have salty sweat or not, your sweat is going to taste salty. So you can’t use that to differentiate between salty and not salty sweaters,” Baker explains. “So if you can, it’s a good idea to do a sweat test.”

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At what point is it important to replace the minerals lost in sweat during exercise?

It’s important to keep your body from losing too many electrolytes through sweat, but you may not need to worry if you’re only doing a 25-minute home workout.

“It’s most important to think about replacing your electrolyte losses during longer workouts— especially for the workouts where you’re losing a lot of electrolytes because of heavy sweat losses or you’re somebody that happens to be a salty sweater,” Baker says.

Baker’s general guideline is If a workout is nearing or surpassing the two-hour mark, it’s probably time to replace some electrolytes. And if a workout is shorter but being done in the heat, you’ll definitely want to do it sooner.

“Gatorade has products with varying amounts of electrolytes so that we can help facilitate the personalization of electrolyte replacement as well,” she says. There are plenty of products to choose from that suit different goals, from an average gym goer to serious endurance athletes.