Keep in mind I'm not a doctor but....
My son has been on Adderall and Adderall XR for years. His psychiatrist thought we'd try taking him off of it a couple of years ago to see if maybe he'd "grown out of" his need for it. NOT a good thing. He bounced off the walls and couldn't focus for more than a minute at a time if he was lucky. He hasn't had any side affects from it at all. He's got an appetitie and is pretty lanky but then again so are all of his bio sibs. Bio mom is skinny too but I'm not sure if that's genetics or just her lifestyle. He's also now "zombified" either. In fact, when he was younger (11 ish), he would be on the correct dose but still have lots of energy. So much so that I would have him run a couple of laps around the back yard to burn some off. Overall, for my difficult child it's been a good medication for him. He's also on a mood stabalizer and some people don't do well with a ms and a stimulant but he's never had any real issues with it.
If you have concerns or questions, don't hesitate to talk to the doctor about it and do research on your own.