Fast Food Nation was a very interesting read and went into many different aspects of the fast food industry (& didn't focus entirely on McDonalds).
I'm sure that Super Size Me has a serious point, but why did it need the guy to eat Macdonalds morning, noon and night for a month? Surely we all know that eating that kind of food so often and for such a long period of time is likely to affect your health? Methinks he really likes the food!