2 things I can add here.
you might rest a long time ingame without eating, running around and similar, or even by doing so, to loose waight, but before you log off, ensure to do something that saves your status, like changing the Lobby, so it is ensured the work was recognised. Do this Always when you realised the effekt of loosing waight, to ensure it is kept.
The second thing is, if you play a female charakter you never gonna gain visual waight. You always stay slim (if you choosen this while creating your charakter). At the same time you have the system telling you your fat in red with an arrow pointing right to the sky. So the mechaniks use the status but ist not vissible for females.