The appeal of detox tea is straightforward and endlessly promising: drink me and be thin. You don’t have to look very far to see detox tea companies equating thinness to health, and then turning around and selling you a thinner version of yourself in the convenient form of a celebrity-endorsed Instagram post and a few dedicated swigs of tea. The sales model is one that detox tea giants like Skinny Mint, SkinnyMe, Flat Tummy Tea, Slendertoxtea, Bootea, and Skinny Teatox have capitalized on. With promises of weight loss often directly in the company names, it’s clear that “detoxing” has become a convenient euphemism for what these teas really are: glorified, and potentially harmful, weight loss supplements.

The do-nothing-and-be-rewarded mentality is reminiscent of sketchy diet pills like Hydroxycut and Lipozin, only this time the message has been diluted through a seemingly innocuous substance. Tea is synonymous with comfort. It is safe and familiar. There is no way it could ever hurt anyone more than the possibility of a burnt tongue. Now that it also promises the benefit of effortless weight loss, it’s only natural we would want to try a cup.

But when it comes to detoxification, Stella Metsovas, a gut health specialist and California-based certified clinical nutritionist, is quick to warn against placing too much faith in something marketing itself as a quick fix: “The golden rule of creating a healthy digestive tract is to never rely on a product for the relief of ailments like constipation, or that believing a supplement is going to detox your gut from harmful bacteria — they should always be considered as ‘in addition to’ a healthy diet,” Metsovas tells Teen Vogue. “Nothing will magically detox your digestive tract — which includes your colon — unless your diet has a large percentage of plant-based fibers.”

Yet the magical promise of weight loss and detoxification through tea seems to be working: to date the #teatox hashtag alone has spawned over 300,000 Instagram posts. And celebrities like Kylie Jenner, Vanessa Hudgens, and Lindsey Lohan have all posted pictures endorsing various brands. Despite there being no hard evidence backing the claims made by tea companies that detox teas cleanse human cells, the industry has, by all accounts, flourished.

Beyond the inspirational Instagram posts and glamorous celebrity endorsements, the hype behind detox tea doesn’t quite add up: how can tea alone make you lose weight? The answer, it turns out, is that it can’t. At least not in any way you want to experience.

Detox tea programs usually come in two parts: a daytime tea, and a nighttime one. The daytime tea is riddled with caffeine from blends of yerba mate, guarana, and green tea. Caffeine is known to have a diuretic effect. While some studies have shown a link between caffeine consumption and weight loss, others have also gone on to find a link between caffeine consumption and weight gain, leaving the evidence for weight loss from caffeine consumption in the dark. But daytime teas don’t stop at caffeine: some also contain dandelion root, another known diuretic. “The weight loss [from detox teas] is primarily, and probably all, water weight,” Dr. Karin Kratina, a nationally recognized nutrition therapist, tells Teen Vogue. “If true weight loss occurs, it is because a caloric deficit also occurred from a change in eating habits.”

The nighttime tea — billed as the “cleansing and detoxification tea” — is where the real weight loss, or “detoxification,” happens. This is largely due to senna root and leaf. Senna is an FDA-approved laxative used to treat constipation and clear the bowels of patients pre-colonoscopy. It works by irritating the colon to empty its contents and is known as a “stimulant” laxative. Basically, ingesting senna is going to make you have go to the bathroom… a lot. And afterwards you’re going to feel lighter because you have successfully emptied out the entire contents of your intestines. While pooping out a pound or two might seem like an activity that’s innocent enough, the laxative process isn’t usually quick or painless. As ridiculous as it sounds, trips to the bathroom can take hours to complete after senna use. It’s why you’ll find warnings like “ensure you have ready access to a toilet during the day until you know how your body reacts to the tea" on nighttime detox teas.