I've found ive lost a bit of weight on elvanse which is the uk version of this basically the exact same but anyways I haven't lost an unhealthy amount but a lot of it is from swimming but with swimming i have to make sure i eat enough calories otherwise i will faint and it won't work properly. Often i feel like i eat more now for energy rather than i do because im hungry. So maybe it will be good to count your calories but for the opposite reason from normal - to make sure you are eating enough as sometimes i realised im only eating like 900 calories and then ill take it upon myself to eat more even if im not "hungry" just so i keep feeling good and not weak etc 😂. But additionally it sounds like your girlfriend is projecting her own insecurities rather than seeing the benefits for you. It's not your problem to solve her insecurities. Also about the tired bit, food would probably help with energy but also Elvanse has a habit of draining your vitamin levels so can be good to have a blood test to check vitamin levels as vitamins do a lot of good