11 viral diets and the ones that actually work

The hype: Hollywood fitness trainer Harley Pasternak is the author of the New York Times best seller "The 5-Factor Diet," which encourages people to eat five 5-ingredient meals per day, each of which allegedly take just five minutes to prep.

The truth: The plan, more of a lifestyle and less of a temporary "fix-it" diet, is based around the idea that each of your meals contains one of each of four main food groups: protein, complex carbs, fiber, and healthy fats. The fifth group is water or other sugar-free drinks.

The hype: Singer Christina Aguilera reportedly went on the seven-day Color Diet at one point, eating foods of one color each day. Day one starts with white, which is followed by red, green, orange, purple, yellow, and, on the seventh day, all of the colors.

The truth: Different-colored foods do often provide different nutrients, so the temporary plan might help encourage you to try new things that you might otherwise ignore, from purple yams to emerald green kale. If you start by eating one color of fruits and veggies every day, you can establish a healthy habit of incorporating color into your diet, but don't forget the protein and whole grains.

The hype: The day before his 44th birthday, artist Jay Z joined partner Beyoncé in a 22-day "vegan challenge." Now, both stars are partners in a vegan food company founded by their personal trainer, Marco Borges, called 22 Days Nutrition.

The truth: As with any eating plan, if you can stick with the lifestyle changes it advises for a long time, it might be worth a shot. Experts also advise people transitioning to a vegan diet to replace meat and dairy with foods that have a similar nutritional profile, like tofu, beans, and dark, leafy greens to ward off nutrient deficiencies. Also, instead of Bey and Jay Z's plan, which costs about $600 for 22 days, you might want to simply try going vegan with a friend.

The hype: Singer Katy Perry claims the "M Diet," which involves swapping a meal with raw mushrooms for two weeks, helps her get lean only in select areas of her body, namely her waist, hips, and thighs.

The truth: "There's no evidence that any diet … will help you lose weight in a particular spot," registered dietitian Katherine Tallmadge told LiveScience. Again, you can chalk any weight loss that results from this plan to calorie restriction. While a traditional meal is around 700 calories, a cup of raw mushrooms is about 20.

The hype: Shortly after singer Sam Smith took home four top awards at the Grammys in February, he started shedding pounds, crediting his transformation to nutritional therapist Amelia Freer and her "Nourish and Glow" 10-day plan. Freer also had him exercising regularly and eating lots of fresh veggies, fruit, lean meats, and some seafood while abstaining from pastries and ice cream.

The truth: There's nothing about the plan that's outright unhealthy. If you can keep up the habits you start with in the 10 days on the plan, it might work for you.

The hype: Snooki reportedly lost weight in 2010 with a diet based on special cookies created by Sanford Siegal, who calls himself "The Cookie Doctor." The three-week plan involves eating six of the 90-calorie treats a day and one small meal.

The truth: Like the Baby Food Diet, the reason the Cookie Diet could be linked with weight loss is because of calorie restriction — all of those cookies only add up to 540 calories, about the equivalent of a single meal. A look at the ingredients in Siegal's "cookies" (wheat bran, beef protein, egg whites) also suggest they're more of a high-protein, high-fiber snack than anything else.

The hype: The Baby Food Diet, which involves eating 14 jars of baby food with the option of adding in one low-calorie meal each day, has been traced to celebrity trainer Tracy Anderson, who's since denied supporting it. Celebrities including Reese Witherspoon have allegedly tried it.

The truth: The diet is likely linked with weight loss because it involves calorie restriction, rather than having anything to do with the baby food itself. An average jar of the stuff has around 80 calories, so if you ate the number outlined in the diet, you'd end up with roughly 1,000 calories each day, not counting the allotted single meal.

The hype: Slashing carbohydrates from your diet will force your body to burn fat, and celebrities including Adriana Lima, Megan Fox, and Mick Jagger are supposedly doing it.

The truth: First developed to treat childhood epilepsy, ketogenic or "keto" diets have become something of a fad among the Silicon Valley crew. The plan mimics starvation, sending the body into a metabolic state called ketosis. Some studies have linked the plan with a variety of health benefits from weight loss to a reduced risk of chronic disease, but it can also come with side effects like nausea, headaches, and fatigue — all of which could make it tough to stick to.

The hype: Singer Tim McGraw sticks to a paleo diet, a meal plan free of dairy, legumes, refined sugar, alcohol, and grains.

The truth: The US News and World Report ranks the paleo diet 36 out of 38 diets, saying that it can be tough to follow and is somewhat "nutritionally incomplete."

The hype: Beyoncé reportedly used the Master Cleanse to slim down before the movie "Dreamgirls." The cleanse involves drinking a lemon juice-based mixture to allegedly clean out the system and speed weight loss.

The truth: Any diet that's based around the idea of detoxing is probably bogus, since our bodies naturally detoxify themselves.

The hype: Actresses including Jennifer Aniston, Kirsten Dunst, and Gwyneth Paltrow, have all reportedly done the pH or "Alkaline" diet, which advocates swapping so-called acid-forming foods like meat, fish, dairy, and grains with alkaline ones like fruits, nuts, beans, and vegetables.

The truth: The diet is based on the misleading idea that you can change your blood pH with food. While the pH of the stomach is acidic, the blood is slightly alkaline, something the food you eat can't change. Still, one positive part of the diet is that it advocates eating more fruits and veggies, something most dietitians agree we should all be doing.