Fatgirl Goes to the Fugly Pride Parade by C.S. Johnson

Kallie Grande-White never wanted to be a superhero, let alone a superhero who was known for sitting on her enemies. But after accidentally devouring her former-government-worker grandmother's radioactive doughnuts in a fit of sad rage, that's where Kallie found herself.
And now, the superhero schtick is nothing even close to the supermodel career Kallie longed for, but to make it worse, the Fat and Ugly Parade has come to town, with an invitation for Fatgirl to be one of their leading grand marshals. Kallie's determined not to go, but that doesn't mean anything to the villain behind the mysterious packages of radioactive doughnuts that are transforming people into their literal worst fears - an experience Kallie is all too familiar with herself. And when Sorra March, a leading figure in the Fugly Pride movement, is the next Alterant to show up in Cuttingham City, Kallie has no choice but to step up and save the day.
With Zeus and AB at her side, Kallie heads off to save the city from its biggest Alterant issue yet!