Having successfully championed minorities, women, homosexuals, and rainbow-haired, sexually-confused, surgically-mutilated freaks in science fiction, SF-SJWs have defined their next urgent anti-discrimination priority: fat chicks.
You’ve read a couple books where fat girls get to be loved in the real world, and that’s wonderful, but fat girls don’t get whisked away into alternate worlds and told they’re a long lost princess. Fat girls don’t get to see the magical underside of New York City. Fat girls don’t save planets.
It’s an interesting dichotomy. Many, if not most, fantasy writers are fat women, but fat women are apparently discriminating against fat women in their books, either because they are a) self-hating or b) subject to a false consciousness instilled by Society and The Patriarchy.