Five Bite Diet
Despite being developed by a doctor this one is extremely dangerous. Five biters skip the first meal of the day and take only five bites for lunch and another five for dinner. On the upside you can eat whatever you want. On the downside that's not enough food to reasonably survive for an extended period of time and maintain good health.
The premise of the diet is flawed on it's face: eating inline with our paleolithic ancestors is practically impossible given it would vary by location and season. Beyond that, the idea that our ancestors were somehow healthier than we are requires very selective evidence, like focusing on a lack of diabetes while ignoring shorter lifespans. Nutritionists warn that following the diet could lead to a calcium deficiency.
The Maker's Diet
Similar to the Paleo plan, this diet focuses on what it assumes to be a Biblical diet on the grounds that it's somehow healthier for you to eat things that are totally unprocessed and devoid of pesticides. Where things get really questionable are the recommended supplements, which nutritionists argue are not needed if you're eating a balanced diet, pulling the rug out from under the whole premise.
Concocted in the 1880s on shoddy “science” by Horace Fletcher, the idea is that all food should be chewed at least one-hundred times. Oh, and liquids, somehow. On paper this should make food digest better and promote better health. In reality it doesn't do anything outside of wasting time.
Eat Anything Diets
There are many diets that claim you can eat whatever you want with certain caveats (one says you only eat during an eight-hour period each day, while another says eating anything at all will eventually force self-control onto you... somehow). But in either instance you've taken the idea of a balanced diet and smashed it to pieces. Without that balance, there is no health.