One thery for the issue with HFSC(?HFCS) is they reduce the body's ability to measure how many calories it has consumed which promotes over eating. The other problem is they tend to be in high calory low nutrition food so people need to still need to eat nutrent food and the "empty callories" don't really help.

PS: While I have never heard much mention of this, I suspect people crave food that contain nutrents they are missing. So hunger is probably a fiarly complex system that might not be all that robust to "new" food types.

HFCS might be a contributor, but would simply show up as an increase in energy intake. If you go from eating X amount of sugars in a day to eating 2X amount of sugars in a day, that just shows up as an increase in caloric intake.

This article was trying to contrast energy intake with exercise to see if the obesity seen was being caused by an increase in the amount we ate or a decrease in the amount we exercised (rather than seeing what foods might have been the culprits of the increased energy intake).