Since September, the Japanese have gone bananas over the Morning Banana Diet, which is why you can’t find any clusters of the world’s most popular fruit in local supermarkets. The run on bananas started when former opera singer Kumiko Mori—who weighed more than 220 pounds—appeared on a popular TV show and described how she lost 15 pounds by eating nothing but bananas for breakfast. That’s all it took for Japanese girls and young women obsessed with their weight to stampede supermarket shelves in search of elusive bananas.

The Morning Banana Diet is simple: you eat a banana (or as many as you want) for breakfast with a glass of room-temperature water. You can eat anything you want for lunch and dinner, even enjoy a mid-afternoon snack. But no desserts and no eating after 8 p.m.

The Morning Banana Diet—originally introduced on a social networking website called maxi—has taken Japan by storm, but then again, the Japanese love the latest fads. A year ago, the natto diet (fermented soybeans) was the rage.

Here in the U.S., we love our share of fad diets, as well. Remember all the hype surrounding the “Master Cleanse” diet after singer Beyoncé Knowles shook off 22 pounds before playing the role of Deena in the hit film Dreamgirls? Beyoncé lost all that weight after embarking on a crash diet that consisted of drinking a mixture of water, cayenne pepper, and maple syrup—and starving herself of regular food. When the supermarket tabloids splashed photos of her newly svelte figure, shoppers made a dash for the maple syrup on Aisle 4.

While Beyoncé’s “maple syrup diet” may be one of the more outlandish fads to capture attention in recent years, her story is an instructive reminder that millions of Americans are on the lookout for the Next Big Thing to lose weight swiftly and effortlessly.

Fad diets make up a tidy chunk of a multi-billion dollar weight-loss industry that churns out books, CDs, DVRs, shakes, bars, pills, supplements, gym equipment, and infomercials for everything from the latest “weight-burning shakes” and “slimming supplements” to “bun trainers” and “ab sculptors.”

Yet as anyone who’s suffered through a crash diet will tell you, weight quickly lost is weight destined to return. Nearly all these diets cannot be sustained because these food-restrictive regimes do not deliver a variety of well-rounded, nutritious foods necessary for good health.

In fact, these fad diets should come with the following health advisory: “Don’t do this at home.”