"King-Size Homer" was written by Dan Greaney, and directed by Jim Reardon. It was the first episode Greaney wrote for "The Simpsons". Prior to this episode he was working as a lawyer and was contemplating moving to Ukraine to work for a start-up company. He said that this episode "saved" him from doing so. Greaney pitched some ideas to the writing staff, but none of them were satisfactory, so then-show runner Bill Oakley gave him the idea for this episode. Oakley had Greaney come to Hollywood to write it, and when Greaney showed the first draft to the staff, they liked it, so Oakley hired him.