Custom girls should appear in town at their base BMI (though they will passively fatten up if Dizzy's is open in town, so don't wait too long to meet her!).
I can change this so there's always the possibility you'll run into a slim girl in town.
Maybe there could be a little chance at running into a slim girl only at the Leisure Centre, like they're the only ones using the gym after all this or something similar?
