Kevin Federline is going to have to stop eating at McDonald's. Nicknamed K-Fat for the pounds he's packed on, Britney Spear's porky ex is on board for the next season of Celebrity Fit Club, TMZ reports, complete with embarrassing shirtless photos of the blown-up former model and wannabe rapper. He'll be joined on the VH1 reality show by Bobby Brown, Nicole Eggert—and his other babymama, Shar Jackson. (More Kevin Federline stories.)