I can think of several IF adventures I’ve read in the past that had some fun with characters both gaining and losing weight. IMHO, how things happen within a game’s narrative is important; would it make sense for something to happen within the game? It’s also a question worth asking of the characters in the game; how do they react to weight changes? Do they have agency to react to player actions?
That said, I don’t think Forks needs to necessarily try to be everything for everyone. That’s a great way to kill a project before it’s finished.