I don't. Certainly it doesn't help and, of course, Americans should eat much better than they do, but ...
I think the most important factor is that our built and cultural environment are constructed to make us obese.
If one does not live in a modern city center one barely ever walks. Most Americans sit all day - at a desk or in a car.
Further, many Americans are 1-2 generations removed from "the farm" and are still heavily influenced by habits like "three square meals per day" that made great sense on the farm and make no sense at all in the city.
We're bad at being urban.
I contrast us with people I see who are good at being urban. The old Chinese women in the park doing Tai Chi every morning. The 70+ woman I saw running (running!) to get the bus in Zurich. The Spanish people I lived with who sort-of ate one big meal every day at 14:00 ...
We'll get there ...