I make jam at home. I usually just heat the fruit (strawberries, raspberries etc) alone, with not even added sugar. That's group 1. If I add sugar, it becomes group 3. If I did add pectin for some reason, it becomes group 4.

Yes, I agree that group 4 is very broad, but I think as an initial attempt its good. Breaking things down into further groups is going to confuse people a lot more, especially because there are no distinct categories here. Too much overlap. Just asking people to eat less of group 4 is a much more reasonable public health objective.