Haven't seen Supersize Me, but have read Fast Food Nation (yikes, just had to correct what I first typed: Fat Food Nation

).
I didn't eat at McD's for at least two years after I read that.
But my choice not to eat fast food had to do with more than just the poor nutrition that is included with fast food, but also with the economics of fast food and that cooking is something that is performed on an assembly line. In other words, the types of jobs and wages provided by fast food companies, the lack of security at many fast food locations (open late with just a couple of teenagers minding the store), and also the way that suppliers for fast food companies and smaller farmers are treated, and how livestock are treated. (These are some of the same reasons I don't shop at
Walmart - obviously not referring to livestock here).
It's the whole fast food culture that I don't like. I also disagree with the statement that natural foods aren't any better for you than processed foods. I think that is really a difficult statement to evaluate. It depends on how you define processed vs. natural. If you define processed as fresh vegetables that have been packaged for purchase at a grocery store vs. vegetables that you grow yourself, then, okay, I'm with you. If, however, you mean to tell me that frozen TV dinners are nutritionally equal to a meal that you prepare yourself, then I can't say that I'm in agreement. Food such as these usually have much more sodium, fat and sugars than unprocessed foods.
I use convenience foods (i.e. bagged salads), and don't think it takes any longer to broil a lean piece of steak or chicken cutlet than it does to bake a TV dinner or fry/broil a hamburger. But I still think that you get a better quality of food from eating lots of fresh vegetables (cooked and raw, even if "convenient") and from eating lean protein with minimal additives (including fat and salt) than you do from eating pre-prepared frozen dinners or a burger and fries from McD's. My sister in law is a nutritionist, and I tend to think she would agree with me. But she would also tell you that portion size is equally important. Just because you cooked your own pasta does not mean that you can eat a pound of it every day, and doesn't mean you should not control how much fat, what kind of fat, and how much salt you add to it.
That's not to say I never eat fast food, just like I'd never even attempt to get away with telling anyone that I don't eat chocolate. It's just that I view fast food the same way I view chocolate (okay, well not really, chocolate is it's own special category), dessert and potato chips. It is to be eaten sparingly.