As The Odyssey continues to draw people to the movies for the fourth week in a row, there has been much discussion about how Matt Damon got in shape for the film. His personal trainer says the actor’s muscle-y physique in the movie was a result of an overhaul to his diet and a consistent 5-workout-a-week schedule. But in a recent interview with Andy Cohen, the 55-year-old actor also credited a “gut cleanse with my doctor, who told me to take 90 days to not eat gluten, dairy, alcohol, caffeine, or sugar.”

While the main motivation for Damon’s restrictive diet was shredding to reach Greek god tier, gut cleanses have also become popular among wellness enthusiasts seeking primarily to improve their digestive health. Also called a colon cleanse, the practice involves eliminating certain food groups and, in some cases, taking stacks of supplements to supposedly remove toxins and waste from the gut, reduce bloating, and boost energy (weight loss, many of these influencers often say, is a common side effect).

The idea has been around for a while (you might remember the mid-Noughties Master Cleanse craze that instructed people to consume a only a beverage made with lemon juice, maple syrup and cayenne pepper for 10 days or more), but the concept has been experiencing a resurgence on TikTok recently, where the wellness-minded recommend doing a cleanse with antimicrobial herbs every six months to get rid of parasites or a gut reset to ‘clear pathogens’. But is there any science behind these cleanses? We asked experts to weigh in.

What is a gut cleanse meant to do?

Encompassing a huge range of different protocols, the gut cleanses suggested by influencers can last anywhere from three days to three months. The first step typically involves cutting out food groups or ingredients that are seen as harmful for the gut lining, typically some combination of sugar, dairy, gluten, alcohol, or all of the above.

“Other gut cleanses remove solid food altogether, replacing it with juices or soups,” says Dr. Federica Amati, head nutritionist at ZOE Health and nutrition lead at Imperial College London, who has seen these diets appear in “different guises” over the years. “But a lot of them are not evidence-based. It’s a promise that a short-term intervention will magically reset your body and make you feel better.” Often aimed at people who have IBS (Irritable Bowel Syndrome), these week- or month-long regimes claim to reduce symptoms such as bloating, constipation or diarrhea, and leave people feeling more energized.

Some colon cleanse protocols also recommend consuming supplements, which health influencers say will detoxify the GI tract. They also claim that activated charcoal (which is used as a legitimate medical treatment for poisoning and overdose) binds to impurities and removes them from the body, while probiotics and enzymes are meant to feed the microbiome and supercharge digestion. More extreme programs also recommend taking laxatives to get the bowel moving, plus antiparasitic herbs, drops or pills to kill bugs lurking in the intestines. “Wormwood, black walnut and clove are the ‘big three’ you see marketed for parasite removal,” says Jordan Glenn, head of science at SuppCo. Recently, some biohackers have also been raving about zeolites, a category of supplement said to remove heavy metals from the gut.

Does a gut cleanse work?

It stands to reason that forgoing bread, desserts, cheese and booze in favor of veggies and lean meat will put a spring in your step, but that’s not because your digestive system has been ‘detoxified’. It’s just because you’ve been consuming more gut-friendly foods, Dr. Amati says. “The gut is one of our body’s main detoxification organs, along with the liver, the kidneys, and the lungs. Anything we eat that the body doesn’t need anymore gets put into our feces.”

Similarly, there’s no strong evidence that gut cleanse supplements will support this process, and some of them could be harmful. One small 2019 study on clinoptilolite, an ingredient commonly found in zeolite supplements that purport to reduce heavy metals from the body, shows that it could improve intestinal barrier function and decrease inflammation, but with “potential side effects like decreasing your sodium and calcium, and also increasing your lead levels,” says gastroenterologist Dr. Leybelis Padilla, founder of Unlocking GI.