I take issue with this because was it really the sugar or were you reducing and eliminating other bad elements from your diet? Cup cakes and ice cream, for example -- it's not the sugar -- it's the high fat combined with sugar causing you problems.
Good point. My feeling is that this rule of cutting added sugar is a good rule to actually eat mostly healthy food. There is counter example to that of course. I am not doing a scientific study, I am just tired to gain weight if I don't run 3 times a week.
There's nothing wrong with high fat on its own. Sugar on its own is not good (might as well eat anything else, you'll save your teeth). But put the two together and you get heart disease.