1. Just listen to it and say she looks great and she doesn’t need to lose any weight. Most of the time this doesn’t always work....some women just like to express what they may be thinking about with you like you are one of their girlfriends. Her appetite is real....she has gained and is always hungry but doesn’t want to sacrifice anything....so she will probably get Fatter, which is a win for you accept having her always complaining about it.
2. If you are truly sick of hearing it .....next time she brings it up. Just say yes....you have gained a bunch of weight but I love it and wouldn’t even mind if you got really Fat. Maybe this will work with her.....who knows.