Detox has become a seriously watered-down term because of the many over-hyped products that are peddled in its name–from juice cleanses to infomercial foot pads.

The truth is, your body is set up to take care of the process on its own via a variety of systems, but there are a handful of ways you can pitch in to help it perform, including one you may not have explicitly thought of: exercise.

“The primary detox organs are the liver and kidneys, but sometimes they’re not able to get rid of certain toxins because the load is too large,” explains Manhattan-based functional medicine physician Jeffrey Morrison, MD.  “What doesn’t leave gets stored in the fat, so the body gets rid of it through a secondary system, which is sweat.”

That’s right, add “sweating out toxins” to the long list of reasons you should hit the gym, along with boosting your mental health, making sure you can climb the stairs when you’re 80, another reason to wear cute leggings, and so much more.

Don’t you know that you’re toxic?

First off: why detoxing even matters. Dr. Morrison points to the many environmental chemicals we’re all exposed to daily, many of which have not been thoroughly studied when it comes to long-term health effects. For example, a CDC report from 2009 that looked at exposures by measuring levels of more than 200 chemicals in human urine and blood showed that nearly all people surveyed had measurable levels of BPA and mercury in their urine.

“Fat is a storage for both calories and toxins. It’s our dumpster.”

It’s important to note that the substances being present in the urine doesn’t prove they’re causing harm, but it does demonstrate how ubiquitous exposures are, and Dr. Morrison points to the build-up of so many chemicals in the body, the cumulative effect of which is unknown.

“Fat is a storage for both calories and toxins. It’s our dumpster,” he explains. “Once toxins get into the fat, mostly they’re pretty inert and not causing any harm. But then if the fat gets overloaded, if a person is consuming so many toxins, then people start noticing problems, like skin issues, circulation issues, the metabolism starts shutting down.”

How sweat helps

Most detoxing happens through the liver and kidneys, but when the amount exceeds the capacity the body can handle, Dr. Morrison says, your pores will start to pitch in. “There’s only so much they [the liver and kidneys] can grab and package. If there’s more coming in, then the body has to manage it. That’s when the body starts trying to sweat things out.”

Research backs up the point, he says, with multiple studies that have shown heavy metals like arsenic, lead, and mercury in sweat after exercise (and saunas). “They also know that there are some fat soluble toxins in the sweat as well. Just like you can absorb them through the skin, you can also pass them back through it.” Think endocrine disruptors like BPA (learn more about those here).

Most detoxing happens through the liver and kidneys, but when the amount exceeds what the body can handle, your pores will pitch in.

Which brings him to an important piece of advice: If you’re looking to use your spin session or Bikram Yoga class as a detox opportunity, you’ve got to ditch the currently trendy “wear your sweaty athleisure all day!” mentality.

“The next step is soap and water in the shower. The soap will help carry away the fat soluble toxins,” Dr. Morrison says. “If you don’t, they’re just going to get reabsorbed through the skin, and all that hard work was for nothing.” When it comes to detoxing, at least.

Too. much. sweat. Try these 9 natural deodorants that are good enough for your intense workouts.