HFCS isn't really used where I am (UK) nor the rest of Europe (dunno about the rest of the world), but we're still getting massively increased obesity.
When one eats traditionally prepared (European, at least) food, it is much harder to become very fat, even if you are eating “unhealthy” foods with a lot of fat in them.
We really need regulation forcing processed foods to pass some kind of satiation-per-calorie test. It’s mind blowing that this isn’t a top level political issue.