While enlightening, the above discussion doesn't really indicate whether or not sugar will be added as something to track. If this is a concern for you, I would suggest posting it down in a thread in the bottom category in the list, under FitDay Beta; I am certain that the technical folks working on changes to the site read that much more frequently than they do the threads in the nutrition area. Many folks share your concern, but I don't know if it's a planned addition or not. The tech folks should be able to tell you.
And now that you don't have to be perfect, you can be good.