The Worst Diets Ever: Diets That Don't Work

Avoid these 5 types of diets for best weight loss results, experts say.

By Kathleen Zelman, MPH, RD/LD
WebMD Weight Loss Clinic - Feature

Reviewed by Louise Chang, MD

"Eat what you want, when you want, and watch the pounds disappear!" You've heard of them, maybe even tried them: miraculous-sounding diets that claim to melt off pounds with minimal effort. There are hundreds of these quick-fix diets out there, from the grapefruit diet to the detox diet to the "caveman" diet. But how do you tell legitimate weight loss plans from diets that don't work (at least in the long run)?

One reason's it's so hard to tell the difference is that even the worst diets will likely result in weight loss, at least initially. But it does little good to lose weight, experts say, if it comes right back.

"Don't be fooled into thinking it is because of some magical food, pill or potion. What causes weight loss is eating fewer calories than you burn," says Dawn Jackson-Blatner, RD, a spokesperson for the American Dietetic Association (ADA). "Crazy, unbalanced diets cause weight loss because they are basically low-calorie diets."

After a few weeks on an unrealistic diet, dieters usually become frustrated and give up. This leads to feelings of failure that can help send them right back to their unhealthy lifestyles.

"Fad diets not only fail to produce long-term weight loss, they can lead to deprivation, weight gain, and discouragement," says Michelle May, MD, author of Am I Hungry?What to Do When Diets Don't Work. "In other words, you are often worse off than before you started."

The Worst Diets Ever

Experts who spoke to WebMD identified these 5 types of diets that are unlikely to produce long-term results for most people:

1. Diets that focus on only a few foods or food groups (like the cabbage soup diet, grapefruit diet, strict vegan diets, raw food diets, and many low-carb diets). Beware of any diet that rules out entire food groups. People need to eat from a variety of food groups to get all the nutrients they need, says ADA spokeswoman Andrea Giancoli, MPH, RD.

Yale University's David Katz, MD, author of The Flavor Point Diet, says that while restrictive diets do work initially, they fail over the long haul. You can lose weight on diets that focus on single foods (like cabbage soup), but how much cabbage soup can a person eat? Before long, you grow weary of eating the same foods every day, and cravings for favorite foods lead you back to your former eating behavior.

Keep in mind that all foods can fit into a healthy lifestyle in moderation -- even things like bacon, super-premium ice cream, and chips. And when diets forbid certain foods and dieters envision a life without their favorite treats, those diets usually fail. "Any time you restrict a certain food, it triggers cravings for the forbidden fruit and sets up a restriction-binge cycle," says Blatner.

And what about restrictive diets that offer a rewarding "cheat day"? May labels them "absurd."

"It just doesn't make sense to try to be perfect (whatever that is) on Sunday to Friday while obsessing about everything you are going to eat on Saturday," she says.

2. "Detox" diets (like Master Cleanse, the Hallelujah Diet, and The Martha's Vineyard Diet Detox). Extreme regimens calling for procedures like liver flushes, bodily cleanses, colonics, hormone injections, and more are highly suspect, experts say.

"All the flushes and cleanses are pure nonsense, unnecessary, and there is no scientific basis for these recommendations," says Pamela Peeke, MD, chief medical correspondent for the Discovery Health channel. "Your body is well equipped with organs, such as the liver and kidneys, and the immune system, to rid itself of potential toxins and does an excellent job of cleansing itself without needing flushes or cleanses."

3. Diets with 'miracle' foods or ingredients (like supplements, fructose water, bitter orange, green tea, apple cider vinegar). Dieters are always searching for the food, pill, or potion that will help them lose weight, but unfortunately, there are no such miracle ingredients."No one single food or group of foods eaten together or at a certain time of day has any impact on weight loss," notes May.

Be leery of any plan that recommends a shelf full of supplements, enzymes, or potions (especially if you purchase them from the diet book author or company).

"You don't need expensive supplements," says Blatner. "If you want to take a once daily multivitamin for nutritional insurance, that is fine, but otherwise, we recommend you get your nutrients from food."

4. Fasting and very low-calorie diets (like the "Skinny" vegan diet, Hollywood Diet, and Master Cleanse). Fasting has been a cultural and religious tradition for centuries, and is fine for a day or so, but fasting for weight loss is counterproductive, Giancoli explains.



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