Hey im christina im 15years old and have been on adderall since i was 10. Adderall could cause compulsiv behavior if the dose is just a little to high for him. For his weight loss, yes its completely normal to have a back and forth (gain and lose) weight for being on adderall. When he dosnt take the medican ull notice his hunger coming out. Adderall depresses ur appitite which causes weight lose so its really cuz he's actually eating less but if he continues to not eat then a eating disorder with be soon to happen like me... to fix that and to prevent him from getting a eating disorder have him take it only on week days and have him off it on weekends so his hunger wont be a problem.
Some loss of appetite is almost always reported in most individuals. Insofar as compulsive behavior is concerned, since I began taking Adderral I cannot stop chewing gum, to the tune of about five packs a day--SO WHAT! As long as the behavior is not hurting him or anyone else, that is to say, as long as it is harmless, who cares as long as the benefits outweigh the negatives.
I would be much more concerned about him developing an addiction to this drug as he grows older as opposed to some idiosyncracy he has while taking it.
Adderall is highly addictive, watch him carefully and if possible do not allow him to take the drug every day. I only take it 5 or 6 days out of 10!!!!