I notice that if I have lots of HFCS items I suffer from semi-diabetic type symptoms if I go too long without food: an urgent desire to eat, cold sweats, the shakes, blurry vision, etc. It's usually not too bad, but sometimes can pretty much take me out of commission. For years, before I figured out it was HFCS, I tried to deal with it by constantly eating which made me very heavy.
About a year ago I figured it out and have systematically gone about trying to eliminate HFCS from almost everything I eat, which is easier said than done. In the U.S. at least, it seems to be in almost everything from Soda to Bread to Ketchup. I also notice that when I travel overseas, I can eat with relative abandon and not suffer any of the typical ill effects I have from HFCS loaded food in the States.
I noticed within a week of doing this that I could actually get hungry again without getting "sick" and go thus go longer between meals. In the last year, I've lost about 15-20 pounds by just eliminating HFCS from my diet but not making any conscious effort to change my diet or exercise habits.