According to Marie Marcus, MS, RD, CDN, nutrition director at Nourish Snacks, these types of diets appeal to people because they have a lot of structure but only require a short commitment.
“Unlike lifestyle change diets, the finite time period of the watermelon diet gives dieters a realistic, achievable goal,” she says. “We’re more likely to willingly punish ourselves if we know it’s only for a few days.”
And with watermelon as the main selling point, Marcus says, “We’re more likely to sign up for a diet if it means we get to eat something we love all day.”
Watermelon is good for you, it’s true. In addition to nutritional benefits, it provides a good deal of water.
“The watermelon diet is really more of a cleanse that relies on the fact that watermelon is over 90 percent water,” explains Marcus. “So it’s low in calories and provides some vitamins and minerals. It’s hydrating, refreshing, and can help you feel full, at least temporarily.”
Before you go stock up on watermelons, Marcus also offers some words of warning. The diet’s restrictive nature leaves people without any dietary source of protein, she explains. Because of this, she can’t recommend the diet to children, pregnant woman, or anyone with compromised immune function.
She adds that, like all flash diets, it’s not a long-term solution.
“Study after study shows that these fad-type diets don’t work in the long run,” she says. “Once the diet period is over, people fall into their old habits, regain the weight, and look for the next diet to test drive.”
For healthy dieters, some optimism: “In general, I don’t advocate for extreme, restrictive diets and cleanses like this,” Marcus says. “But if you’re generally healthy, it’s unlikely to be harmful when followed for a few days. If you have a plan for how to continue your weight loss efforts once the diet is over, and all you need is a little jumpstart, then go for it.”