Morgan Spurlock successfully managed to "shock and awe" in his Super-Size Me documentary. He extrapolated the general trend in modern life to eat too much crap while not getting near enough exercise to it's worst case conclusion that even the doctors did not expect. He force-fed himself at the arches every day but there were side trips to schools where kids were having fries, sausages, and candy for lunch boxed by some cheap food processing company. So it's not just MacDonalds who wish to maintain the status quo but the entire processed food industry and their well paid lobbyists.
My Conclusion: Have an occasional happy meal for variety but eat natural food every day.