I remember Ben Stiller's character saying that when he was younger age 12 he weighed 200-300 pounds, and then he lost weight. Like in this movie.
He acts the same way as uncle Tony.
And it works as a sequel because he goes full circle. Fat as a child, gets in shape, tries to make fat kids get in shape, years later he changes his name due to being known as an insane person who nearly tortured kids to lose weight, opens a gym for adults since he probably has some sort of court order to stay away from kids, events of dodgeball unfold and he goes back to being a fatty