I cut out a lot of sugar this month, but not every last little gram, so I can't really say how that would affect my complexion. My skin looks very nice though. I can't complain.
When I struggled with adult acne a few years ago, my dermatologist had me try several different treatments, and he would always say before I started a new treatment that the acne would get worse before it got better. And he was almost always right. Pimples take weeks to form under the surface of the skin - when you start a new acne treatment, it accelerates this process so the ones that are already forming start popping up faster, but no new ones start forming. So what you get is more breakouts at first, as your skin tries to push all the forming pimples up to the surface and get rid of them. Then, the skin starts to clear. This is my very limited understanding of the process. I wonder if eliminating sugar, as an acne treatment, would have the same affect on some people - it gets worse before it gets better. Could be, but I don't know for sure...