Junk food and fast food are different things - Just because it's served to you in a timely and convenient manner does not lower it to the state of 'junk'.
I think the supersize me was about "fast food" and how over-eating fatty foods to the point of vomiting, was not good for you. I think that's something we can all agree on. If the maker of that film had targeted carrots I'm sure we'd all be wary about turning orange.