There are many diets out there, but the worst ones, the ones that are known to be bad are underwritten by The U.S. govern-cement.
The food pyramid is dangerous for your health, especially if, for the grains section you get processed, sugar filled cereals from the largest section of the supermarket.
And the "fat-free" diet, is DEADLY!!! Your body needs fat. It does not need straight sugar. So, you get that "fat-free" candybar, and you destroy your body and ... get fat. Fat is about the hardest thing for your body to turn into fat cells. Sugar is the easiest. And since your body need good oils for the nerve pathways and your liver, the fat free diet will kill you, or give you alzheimer's, and then kill you.
To be honest, I don't think there is much food at all out there anymore that is rich in nutrients. Not available at price the average citizen can afford at least. It becomes a matter of finding the food that has the less poison in it, and that the body can draw the most nourishment from.