In the UK we are fairly obese and we don't grow corn, we don't have HFCS subsidies, and we don't have have HFCS in everything either - eg coca cola is just plain old sugar here. So I doubt that the US getting rid of corn subsidies will make any difference to obesity - some other sugar would be used instead, sugar cane or sugar beet.

Because regular sugar won't make you obse?

High Fructose Corn Syrup is about half the price of regular sugar.

It would be an interesting thought experiment about what would happen to obesity levels if prices were taxed to the point where the price difference would be eliminated.

Isn't that thought experiment just Europe?

My hunch is that HFCS is more versatile and cheaper than other sugar products, and it can compensate for garbage food in the same way. Therefore passably good tasting food is cheaper and more readily available than anything else.