A couple years ago, Jesse and I watched Morgan Spurlock's movie "Supersize Me." It documents Morgan's quest to track his health as he eats only McDonald's food for a month. The parameters were that he would eat breakfast, lunch, and dinner at McDonald's, would try everything on the menu at least once, and would only supersize a meal if the employees offered it to him. Long story short, his health rapidly deteriorates, in fact appears close to death, and I'm not quite sure if he hits the 30-day mark. In the movie, it's said he eats about 5,000 cals a day.
This YouTube clip sheds some light on how the "Supersize Me" documentary might not be on the up and up. Pretty interesting stuff, I think.