14 Fad Diets You Shouldn't Try

Every day it seems a new diet is ready to make weight loss faster and easier than ever before. Or at least they say they are. "Most fad diets go something like this: Take a few foods, give them 'magic' power, and set a plan to convince people that eating this way and only this way will promote weight loss," says Alexandra Caspero, RD, a nutritionist based in Sacramento, Calif. The following diets might spur short-term weight loss, but many are difficult to follow, have arbitrary rules, and a few could put your health in danger.

Any weight-loss expert would agree that boosting your veggie and fruit intake while reducing the amount of junk you eat is a safe and effective way to lose weight, but this diet bans foods that have been cooked or processed in any way. Why? Raw foodies say cooking destroys nutrients. Though it's true that cooking produce can sometimes reduce nutrient levels, cooked veggies still pack plenty of fiber, vitamins, and minerals, and in some instances cooking actually enhances nutrients while also killing bacteria. The biggest issue with this extreme form of veganism? Food prep—it's totally impractical, says Christopher N. Ochner, PhD, director of research development and administration at the Mount Sinai Adolescent Health Center. Raw foodies spend hours upon hours juicing, blending, dehydrating, sprouting, germinating, cutting, chopping, and rehydrating.

The alkaline diet—also known as the alkaline ash diet and the alkaline acid diet—requires you cut out meat, dairy, sweets, caffeine, alcohol, artificial and processed foods, and consume more fresh fruits and veggies, nuts, and seeds. The diet certainly has positive points; it's heavy on fresh produce and other healthy, satisfying foods while eliminating processed fare, which in itself may spur weight loss. But your body is incredibly efficient at keeping your pH levels where they need to be, so cutting out these foods really won't affect your body's pH, says Ochner. Not to mention there's no research proving that pH affects your weight in the first place. The bottom line: the diet is strict, complicated, and bans foods that can have a place in a healthy eating plan, such as meat, dairy, and alcohol.

Developed by naturopathic physician Peter D'Adamo, the Blood Type Diet is based on the notion that the foods you eat react chemically with your blood type. For example, on the diet, those with type O blood are to eat lean meats, vegetables, and fruits, and avoid wheat and dairy. Meanwhile, type A dieters go vegetarian, and those with type B blood are supposed to avoid chicken, corn, wheat, tomatoes, peanuts, and sesame seeds. However, there's no scientific proof that your blood type affects weight loss. And depending on your blood type, the diet can be extremely restrictive.

Also called the lunar diet, this one is simply fasting according to the lunar calendar. Its quick-fix version involves a day of fasting allowing only water and juice during a full or new moon—and supposedly losing up to six pounds in water weight in a single day. The extended version starts with that daylong fast and continues with specific eating plans for each phase of the moon. While you'll lose some weight from not eating, it has nothing to do with the moon, and it will come right back, Ochner says.

Dr. Siegal's Cookie Diet, The Hollywood Cookie Diet, and the Smart for Life Cookie Diet all promise that eating cookies will help you drop pounds. Of course, you don't get to chow down chocolate-chip cookies—you eat about 500 to 600 calories a day from high-protein and high-fiber weight-loss cookies (one cookie company even makes the cookies from egg and milk protein) for breakfast, lunch, and any snacks. Then you eat a normal dinner, for a total of 1,000 to 1,200 calories a day. If you stick to the diet, you will likely lose some weight, but by depriving yourself all day, you set yourself up for bingeing come dinnertime, Ochner says.

Eat whatever you want—but only five bites of it. On this diet, developed by obesity doctor Alwin Lewis, MD, you skip breakfast and eat only five bites of food for lunch and five more for dinner. "I'm OK with the idea of eating whatever you want in smaller portions, but you need to round out the rest of your eating with nutrient-dense foods to give your body the fuel it needs," Caspero says. "On this diet, even if you take giant bites of heavily caloric food, you're still barely consuming 900 to 1,000 calories a day."

This diet has been around for decades, and there are a ton of variations. Pretty much all involve subsisting for days on only lemon juice, maple syrup, and cayenne pepper mixed in water. "You are essentially just drinking diuretics," Ochner says. "You'll shed mostly water weight." Once you start eating solid foods again, you will gain all the weight back. Common side effects include fatigue, nausea, dizziness, and dehydration. Plus, on an extremely low-calorie diet like this one, you are going to lose muscle, exactly the kind of weight you don't want to lose, Caspero says.

If a baby can grow up eating the mushy stuff, eating some definitely won't hurt you, but guess what: You aren't a baby. Dieters replace breakfast and lunch with about 14 jars of baby food (most baby food jars contain 20 and 100 calories apiece), and then they eat a low-calorie dinner. It's easy to get too few calories for your body to run its best, Ochner says. Besides, who really wants to take jars of baby food to work each day?

The grandmother of all fad diets, the bulk of this plan is fat-free cabbage soup, eaten two to three times a day for a week along with other low-calorie foods such as bananas and skim milk. In the short term, it does yield weight loss. "It works because you are eating a low-calorie diet full of fiber and water to help aid in fullness," Caspero says. "But it's just a quick fix diet. It can also promote bloating and gas from all the cabbage, and is lacking in protein, which is needed to preserve lean body mass. While I am a fan of nutrient-dense, low calorie foods for weight loss, it should be balanced with other foods such as fruits, carbohydrates, healthy fats, and lean protein."

We are all for including produce at every meal, but the various versions of this 80-year-old fad diet instruct dieters to focus all of their meals on grapefruit or grapefruit juice, claiming that the fruit contains fat-busting enzymes that will help dieters lose 10-plus pounds in 12 days. "In reality, any time you are following a very-low calorie diet you will lose weight," Caspero says. And this diet definitely hits that, limiting dieters to 800 to 1,000 calories a day. Some iterations also prohibit eating extremely hot or extremely cold foods, preparing foods in aluminum pans, and requires dieters to space "protein meals" and "starch meals" at least four hours apart.

If you're asleep, you're not eating. Rumored to have been followed by Elvis Presley, this diet takes that simple fact to the extreme, encouraging people to use sedatives to stay asleep for days on end. But sleeping the days away not only starves the body and causes muscle deterioration from a lack of movement, but actually risks death: "Every time you go under, there's a risk," Ochner says. "Sure, you might wake up 2 pounds lighter, but you might not wake up at all."

This edge-of-starvation diet limits you to about 500 calories a day while taking human chorionic gonadotropin (HCG), a hormone that proponents tout as a powerful appetite suppressant. However, there's no evidence that HCG does more than act as a placebo, Ochner says. Yes, you'll lose weight, but only due to the extreme calorie restriction. Though a health care provider may legally give you HCG injections, they're typically used to treat fertility issues in women and the FDA has not approved them for weight loss. As for over-the-counter homeopathic products that supposedly contain HCG? Those are illegal.

"You don't need a doctor to tell you that ingesting a tapeworm is a bad idea," Ochner says. But apparently, some people do. This weight-loss tactic has been around for decades, preying on especially desperate dieters. Here's how it goes: Ingest tapeworm eggs, let the tapeworm eat the food you consume once it gets to your intestines, and then, when you lose enough weight, get a doctor to prescribe you an anti-worm medication. But some tapeworm eggs can migrate to various parts of your body or cause other potentially life-threatening problems. Freaked out yet? Good.

Consuming cotton balls soaked in orange juice—a diet technique may have been born on YouTube, in chat rooms, and on Facebook—is an incredibly dangerous way to suppress your appetite. "This makes my eating-disorder therapy head spin," Caspero says. Not only does consuming cotton balls in place of food deprive the body of nutrients, eating anything that isn't actually food can cause blockages in your intestines. What's more, most cotton balls aren't even made of cotton—they're composed of bleached, synthetic fibers.