Lore:

Nell is a foxy adventurer like any other foxy adventurer, which is a problem for her. Despite her best efforts of doing good deeds, Nell is getting sick of looking like a copy to all of the other vulpine adventurers. She despises the repetitiveness and wants to do something different. It's easier said than done because there seems to be always a large group of vixens who have done the same thing. What's even worse is that Nell often get herself stuck with the common tropes associated with busty, vixen women.

In this case, involuntary weight gain!