There were a few documentaries floating around rebutting Morgan Spurlock's documentary. People have actually lost weight eating the same diet...
When I was a slave to McDonalds, I didn't loose weight. I only ate one value meal a day (super sized) and I gained around 50 or so pounds before I broke free. I swear McDonalds food is addicting. It's too poor of quality to be so hard to give up.