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Sweat might not be the most pleasant bodily fluid out there, but you definitely wouldn’t want to live without it either. Sweating is the main way the human body keeps itself cool, thus prevent overheating. But that’s not to say that there’s no such thing as oversweating — something which can ruin relationships and hurt self-esteem. Excessive sweating may also be a sign of chronic illness.

Why people sweat in the first place

Sweating is a necessary process that cools down the body. When the body senses that it’s starting to overheat, the nervous system signals eccrine glands to produce perspiration. As these droplets evaporate, they carry some of the heat from the surface of the body into the atmosphere. Think of how chilly you feel when you just finished a shower or a swim — the water on the body cools you down as it evaporates, and sweat works exactly the same way. If you image your body working like a car, sweating functions like a radiator, preventing the engine from overheating and shutting down (i.e. heat stroke).

Contrary to some pseudoscientific myths, sweating does not ‘detox’ the body. Perspiration is made of 99% water, and the rest is comprised of electrolytes such as salt. Trace amounts of toxic substances may find their way into sweat in some situations, but the main places where toxins are processed is in the liver and kidneys — not the skin.

When is sweating too much?

You’re outside for only a minute on a hot summer day and you’re already sweating like a leaky faucet while your friend is still dry. What gives? These kinds of situations, which can be more intense or frequent for some people than others, might prompt the idea that there’s something out of order. But the truth is that the amount of perspiration released by the body can vary greatly from person to person — from a liter a day to a couple of liters — and that’s just normal.

That being said, if you’re sweating all the time — even when you’re doing nothing physically or mentally straining at your office job — this may be a sign of hidrosis. The condition affects roughly 2% of the population in the United States and is characterized by abnormal sweating  in excess of that required for regulation of body temperature. A particular type of hidrosis, known as hyperhidrosis, causes sweating only on specific body parts — usually from the palms, feet, underarms, or head, while the rest of the body remains dry. Excessive underarm sweating, also known as axillary hyperhidrosis — is one of the most common types of hyperhidrosis.

Although hyperhidrosis is a physiological condition, a 2016 study involving more than 2,000 participants found that anxiety and depression were significantly higher in those with hyperhidrosis.

Most types of hyperhidrosis are caused by overstimulation of the sweat glands, but in some cases, it may be due to a more serious underlying medical condition. Excessive sweating may be a side effect of other more serious conditions such as hyperthyroidism or diabetes. Menopause and certain medications can also trigger hidrosis. This is why it’s important to talk to your doctor about it.

What triggers sweating

There’s something to be said about exercising and sweating. Physical activity obviously causes sweating but if you’re really fit, you’ll actually produce more perspiration than people who don’t work out regularly. A fit person will also start sweating sooner than a regular individual who doesn’t exercise often because the body is primed to develop a faster cooling response. This makes sense — sweating efficiently cools the body, enabling you to run or lift more. And the more energy you expend, the more sweating is required to thermoregulate the body.

“When you’re fit, you’re able to work harder, generate more power, and sustain that power for longer time periods,” explained Dr. Carolyn Dean of the Nutritional Magnesium Association. “Most of this power output generates heat, [which] means you [can] generate a lot of heat in a very short period of time and for a longer duration.”

Regardless of your fitness level, however, once your exercise is at a rate that pushes you closer to your maximal oxygen consumption (VO2 max), you’ll start sweating. Therefore, a person who is less fit will generate start sweating sooner than a person who regularly exercises if they do the same workout at the same pace. However, if each person works out to their individual VO2 max (i.e. running 10 miles per hour for the fit person and 8 miles per hour for the unfit person), all other things being equal, the fit person will start sweating sooner. Once again, fit individuals sweat more efficiently.

Humidity in the atmosphere can also cause you to sweat more than you would in a drier environment. That’s because there’s already a high density of vapor in the air, so the body needs to produce more perspiration to dissipate heat. Another important environmental factor is temperature; hot air is less efficient at cooling the surface of the body than cooler air, so we sweat to compensate.

Summary

Every person sweats differently, and that’s normal. However, if you find that you sweat in benign conditions (not doing anything straining inside a well air-conditioned room), then perhaps you have a form of hidrosis.

It’s important to keep yourself well hydrated in order to replace all the water and electrolytes lost during sweating. A good rule of thumb is drinking half a liter of fluid for every hour you spend in the gym.