Asked about the diet by Katie Krause on Extra in January, Butler said, “It’s basically a watermelon fast. You’re not actually fasting, because you’re getting something in your stomach.” She added, “I will do it every once in a while when I feel like I’ve just been eating really bad, not only for my physical appearance but for my mental state, too … It’s not something that is unhealthy. It actually is very good for you at removing all that toxic stuff. What watermelon does is it basically clears everything because it is mostly water.” But do dietitians agree with Butler? Here’s an in-depth look at the diet, along with what they had to say.

What Is the Watermelon Diet?

Different versions of the watermelon diet have been making their way around the internet. At its core, the diet involves eating nothing but watermelon for a set time period. Common variations run from three to seven days, and after that, you add in some or all of the foods you normally eat, with or without watermelon. Since watermelon is a low-calorie food — one cup of diced watermelon has about 46 calories, according to the U.S. Department of Agriculture (USDA) — this diet is very low in calories. It’s considered a cleanse or detox diet. YouTubers who try it brag about losing lots of weight — 13 pounds in seven days, for example, and say they stop craving junk food, clear their skin, have more mental clarity and energy, and feel lighter and less bloated. But the dietitians we spoke with aren’t fans. “[Gabi Butler’s] advice about the watermelon diet is more toxic than the toxins that she’s trying to get rid of with this cleanse,” says Bonnie Taub-Dix, RDN, the creator of BetterThanDieting.com and the author of Read It Before You Eat It: Taking You From Label to Table. “It’s a shame that she doesn’t understand her importance as a role model.” Unfortunately, people like Butler who are in the public eye can influence fans to try fad diets like this one. “I’m a huge fan of watermelon and fruit in general, but this diet is not helpful,” says Samantha Cassetty, RD, the New York City–based coauthor of Sugar Shock. “Watermelon happens to be a very healthy food, but there’s no evidence that eating it exclusively is a healthy thing to do. In fact, it’s the opposite.” Both Cassetty and Taub-Dix are skeptical of cleanses in general. “There’s no scientific validity to doing a cleanse,” Cassetty says. “The idea that you could eliminate toxins by just eating watermelon is totally untrue.” Taub-Dix points out that you don’t need a restrictive diet to cleanse your body — your liver and kidneys do that for you. After your days of eating nothing but watermelon end, some versions add light meals accompanied by lots of — you guessed it — watermelon. For others, you revert back to your typical diet. You might choose to repeat the watermelon diet anytime you feel the need for a cleanse or detox.

Vitamin A, which helps maintain your vision, support your immune system, and fight inflammation, according to an article published in September 2018 in the Journal of Clinical MedicineVitamin C, which may boost immunity and lower your risk of chronic diseasesLycopene, an antioxidant that may help prevent DNA damage and benefit your immune system, according to research published in LWT in June 2020Citrulline, an amino acid that may help reduce blood pressure and improve exercise performance, according to a study published in January 2017 in Current Opinion in Clinical Nutrition & Metabolic Care

And if you choose to eat watermelon seeds, the USDA reports that an ounce of them contains 8 grams (g) of protein and 13 g of fat. So, no one is questioning the fact that watermelon is a healthy. But when you make it your only source of food, experts say you’re missing out on the health benefits of a host of other nutrients. “It is unhealthy to make any one food your way of life,” Cassetty says. “A healthy diet includes a range of foods.” Cassetty recognizes that cleanses can be appealing: “If you’ve been eating unhealthily for a while, you might feel like you need to do a 180, and small changes aren’t top of mind. I do understand that desire. I would still discourage it, but I think people are entitled to make their own decisions about their health.” She questions whether using the watermelon diet to lose weight could be a sign of underlying problems: “If you are willing to go to this extreme to lose weight, it could be a sign that you have an unhealthy relationship with your body or with food.” If you exercise when you’re not taking in many calories or nutrients, you could become dizzy, tired, or weak. And following the watermelon diet for a prolonged time might lead to loss of muscle tissue. The watermelon diet doesn’t teach you anything about building sustainable habits that will serve your physical and mental health in the long run. “It is unhealthy to make any one food your way of life. A healthy diet includes a range of foods,” Cassetty said. And, if you’re intrigued by the idea of the watermelon as a cleanse, it’s not going to give you the desired effect. “The idea that you could eliminate toxins by just eating watermelon exclusively is totally untrue,” Cassetty said. “There’s no validity to any type of cleanse.”