I've been on 25mg of Adderall XR since last year. I've lost about 15lbs, but I needed to loose weight.
Adderall hasn't taken away my appetite completely, it just seems to make it so I don't want to eat as much...if I wasn't trying to diet, I could probably eat the way I use to. I have had times where I over ate for a week or so and didn't gain weight. I also had a time in the winter where I was eating a lot less (I follow weight watchers), was exercising, but hit a plateau and actually gained weight...then all of a sudden I started to loose weight again. So, sometimes I wonder if it does have an effect on weight even if your appetite is not suppressed and you aren't eating less. I know that it is an amphetamine, which will speed up your heart rate...so I wonder sometimes If that is why. I check my heart rate regularly and it is always find...so I don't know.
Something to keep in mind with Adderall is acidic foods can have an Impact on how effective it is. Vitamin C shouldn't be taken around the same time as it can make the Adderall less effective.
ADD Forums has a section just for Adderall that helped me a lot in the beginning. Check out the link below.