Fads: A Look at America's Wackiest Dieting Plans

In her quest to shed pounds, Amy Jamieson-Petonic tried the cabbage-soup diet, a hot-dog and peanut-butter diet, and just about everything in between. Then, after an "aha" moment as she tried on a size 22 coat, she said, "No more." She started eating smaller portions and healthier foods, and took up running. Lo and behold, she slowly lost 100 pounds. Fifteen years later, Jamieson-Petonic, now a 38-year-old registered dietitian and spokeswoman for the American Dietetic Association, has kept off all the weight. "Real people can do this," she says.

Easier said than done. A remarkable 41 percent of U.S. adults are trying to lose weight—and their average goal is 37 pounds, according to a Consumer Reports survey published this month. (Two thirds of U.S. adults are overweight or obese.) Small wonder they're tempted to try such, um, unusual regimens as Beyoncé's maple-syrup, lemon-juice and cayenne-pepper diet. Or the grapefruit diet. Or the blood-type diet. But experts say they should try some common sense instead. "They sound wacky, and they are wacky," says Walter Willett, professor of epidemiology and nutrition at the Harvard School of Public Health. "If you do something extreme in your diet, you will likely lose weight in the short term because you're excluding the majority of foods. But it's not going to be something you can live with for the rest of your life, and so it's bound to fail." As swimsuit season approaches, here's a rundown on some of today's odder diet options.

The Astrology Diet
In "Zodiaction: Fat-Burning Fitness Tailored to Your Personal Star Quality," trainer Ellen Barrett and astrologer Barrie Dolnick promote an exercise and eating plan based on the 12 astrological signs. Scorpios are "fiery" and need "cooling foods," says Barrett. "It sounds fun, but there's no scientific backing for it," says the ADA's Andrea Giancoli.

The Blood-Type Diet
In "Eat Right 4 Your Type," Peter D'Adamo, a naturopathic doctor, argues that people should eat according to their blood type. A type A, he eats lots of fish and avoids processed meats. "There's no evidence that different people with different blood types need different diets," says Willett. So what's the appeal? People "think it's more personal than other diets," says Giancoli.

Single-Food Diets
Grapefruit. Cabbage Soup. Pineapple. Single-food diets are perennial favorites. "They keep coming back," says Giancoli, who admits she tried single-food diets—including her own popcorn diet—before becoming a registered dietitian and trying (gasp!) a balanced diet and moderate quantities. Eliminating complete food groups can lead to nutrient deficiencies. The body needs protein, for example, to build and repair muscles.

The Maple-Syrup Diet
Sounds yummy, but this draconian plan doesn't allow pancakes. Instead, it asks dieters to drink a concoction of 2 tablespoons of maple syrup, 2 tablespoons of lemon juice, a pinch of cayenne pepper and a cup of water. The diet seems new because Beyoncé said she used it to slim down for "Dreamgirls." But it actually took off in 1976, when Stanley Burroughs wrote "The Master Cleanser." "The really critical thing for weight control is to find something we can live with for the rest of our lives," says Willett. "That would not be maple syrup." The ADA's Susan Moores worries that the diet can interfere with the body's balance of sodium, potassium and fluids. It's particularly detrimental, she says, for kids, teens, pregnant women and nursing moms.

Detox Diets
"For some reason, people think our bodies are full of all kinds of toxins," says dietitian Tara Gidus. Some detox diets, including "21 Pounds in 21 Days," call for "cleansing" with colonics. Translation: enemas. The problem with using them to clear the colon of waste: "it's not really waste at all," says Northwestern University gastroenterologist Alan Buchman. "What people describe as 'toxins' include the normal metabolic products of digestion and the normal bacteria that produce vitamin K and folic acid—and other substances that keep the colon healthy.

The final word goes to James Hill, who runs the University of Colorado-based National Weight Loss Registry, which tracks dieters who have kept off 30 or more pounds for at least a year. What's their secret? They eat a low-fat diet and watch their total calories. They eat breakfast and weigh themselves often. And they get 60 to 90 minutes of exercise a day. No mention of maple syrup.