T.O.
I really wouldnt worry to much about it. My daughter is 10 and is 57lbs. The doctors do not seem to be concerned. They said when puberty hits she will start to put on weight... I just pretty much let my daughter eat whatever she wants in her lunch even if it is all fruit... She has gotten better the past few months. She was 50lbs this time last year. So there is a light at the end of the tunnel. Hope this helps...
Also i read the one below me Adderal is probably more known for that then Concerta. My daughter was on adderal wow what a zombie she was. COncerta is great!!