Proponents of the "you can't spell murder without HFCS" crowd can in fact point to statistics showing that American obesity began its rapid ascent at about the same time corn sweetener began its dominance of the edible garbage industry. If you stop there, it looks like a pretty convincing argument. But researchers who like to look at the bigger picture see it another way -- the reason companies switched to corn syrup in the first place is because it's cheaper than regular sugar. Using it pushed the price of sugary foods down, making them more affordable to the masses. So it's not just that we started eating high fructose corn syrup, it's that we suddenly started eating a lot more bullshit.
In actual fact, studies so far have shown that the body doesn't seem to know the difference between high fructose corn syrup and regular sugar. After all, they both contain the same ingredients, in the same quantities. The only difference is in how they're extracted and combined.
Of course, high fructose corn syrup is still really bad for you, as are the foods that are chock-full of the shit. There's also no doubt that our addiction to sweet-tasting foods and drinks is making us fat as hell. It's just that it's no worse than if those same products were made with sugar.
And just ditching the products and eating pure sugar probably isn't a solution.