You’ve probably heard of people using laxatives to lose weight, but the New York Times is calling attention to a new study that suggests just how common the habit really is. According to research on 13,000 people, a whopping 10.5 percent of women aged 23 to 25 have used laxatives to try to lose weight.

Experts say the findings, which were published in the journal Pediatrics in July 2016, are alarming given that laxatives aren’t designed to be used this way—and doing so can actually be harmful to your health. Here’s what you need to know about laxatives, especially when it comes to why they’re not an easy weight-loss solution.

1. There’s not just one type of laxative.

Products like Ex-Lax are designed to irritate and stimulate your bowel, but that’s just one of five methods that laxatives can use to get things moving, Marc Leavey, M.D., an internist at Baltimore’s Mercy Medical Center, tells SELF. Other laxative forms include osmotic products (which prompt water to enter the colon through osmosis, softening poop to make it easier to pass), bulking agents (which add fiber and bulk to poop to help you go), stool softeners (which pull water from your GI tract into your poop, making it slippery so it’s easier to use the bathroom), and enemas (which involve inserting fluid into the rectum, usually to relieve constipation).

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2. There’s no laxative that will help you lose fat.

If you try to use laxatives for weight loss, you may see the number on the scale go down, but it’s deceiving, women’s health expert Jennifer Wider, M.D., tells SELF—that’s actually water weight you’re losing. “Very little to no fat can be lost [with laxatives],” she says. Leavey agrees, explaining that your weight has to do with so much more than “excess poop.”

3. Most are not designed for long-term use.

Bulk-forming laxatives are the only ones truly designed for chronic use. Stimulant laxatives, which are the most common kind used for weight loss, are “relatively harsh” and shouldn’t be used for a long period of time, says Leavey. Why? “The bowel can get used to them, leading to more constipation.” And if weight loss is your goal, that can actually work against you over time, since all that poop hanging around can add pounds to the scale.

4. What’s more, when used over the long-term, laxatives can actually be dangerous.

While it’s usually fine to take a laxative here and there if you’re stopped up, sustained, needless laxative use can have a negative impact on your health. For starters, it can irritate the lining of your bowel and cause all kinds of gastrointestinal issues, Leavey says, and osmotic laxatives can drop your blood pressure and even cause permanent kidney damage. Not only that, laxative abuse in general can also cause electrolyte and mineral imbalances and dehydration, which can lead to dizziness, fainting, blurry vision, and even death, Wider says.

Bottom line: This is not a weight-loss method you want to try. “There is no rational basis to try to lose weight with laxatives, and there is a clear potential for harmful side effects,” says Leavey. “Don’t do it.”