Mari, my daughter has never been a good eater, always on the thin side. She was about that size at 2 and I remember us joking that she would really eat only every 3rd day... Her bloodwork has always been in normal range, very controlled CAH, with endo visits every 3 months. I read on this board all the time about overweightness being a side effect of the cortef, however, our children must be a exception to the rule. If you are visiting the endo on a regular schedule and bloodworks come back normal and your ped. is not concerned, then I would stop from worring about his weight. He just might be lucky enough to be a naturally thin person. I sure wish I was one of thoes people!