Talk to a regular doctor first - not a MM doctor if you know what I mean - to see if they have any suggestions. Appetite suppression isn't uncommon with stimulants, but they may have some different ways to help, like non-stimulant treatment (e.g. Strattera).

Otherwise, if they don't have any answers, I can only say that cannabis definitely makes me eat a lot more than I need to. Quitting it has lead to some good weight loss - the appetite suppressing side effects of my meds were never noticeable until I stopped smoking cannabis.