Not sure how big one has to be to earn the nickname Fat Chef, but www.performancebike.com has bike shorts up to 3XL, which they say fits 46-48" waists. They have 3XL jerseys too, and their customer support and return policies are good too. I've used them many times.
These are actually SuperGo's house brand, but Nashbar, SuperGo and Performance are all owned by the same übercompany so Nashbar sells SuperGo's products occasionally. I just bought a few pair of these and they aren't too bad for daily workouts. They have them all the way up to 48-50.