Since I am a fan of eating whatever I want, I sometimes have to wonder at the success of those who restrict themselves to low fat or low carb diets. Christopher Genoves has an explanation: any restricted diet has a calorie advantage. He also explains why the low carb diets are so popular:
Holding to the no-carb line gives one few outs, either at the vending machine or the cupboard. (Those low carb bars are not only disgusting but outrageously expensive.)
There seem to be no shortage of low-fat snack options, so perhaps we're just witnessing a cultural cycle. Rigorously adhering to a restrictive diet outside the mainstream limits your access to snacks, which increases its likelihood of success. Success leads to popularity, which eventually means snacks become widely available, and the diet loses its "out of the mainstream" status. After the vending machines are full of nuts and beef jerky, maybe the food pyramid will become the next big thing.
If any restrictive diet is likely to succeed, then, I propose the color diet. Each day of the week, everything you eat must naturally be that day's assigned color. Let's say white for Friday, red for Sunday, green for Saturday, etc. Blue Monday will probably offer one of the more monotonous menus.