Some of our sodas are made with HFDC too. Maybe different amounts - I dunno. When I was in Canada, everything seemed to be sweeter than in the UK - peanut butter was full of sugar, for instance. Here in the UK, I buy peanut butter that is made out of peanuts and oil. No sugar in it. I don't much like sugar.
With regard to American fatness, I don't know if you're the same as Canada, but in Canada I found people went out to eat all the time, and for extra meals after their evening meal. In addition to their three meals a day, they'd go out for dessert, go out for fries, go out for snacks (huge big snacks!), go out for breakfasts which were huge stacks of pancakes with syrup. Portions in restaurants were twice the size as they are here. And socialising always involved lots of food. In the UK, when people get together, it normally involves a cup of tea - or alcohol, depending on what sort of get-together it is. But we're also getting fatter as a nation. Lots of junk food and fast food, and kids spending time on their computers rather than going out to play.