Edit: Yes, bigorexia is a term. It was the term they used on the preview for the show, and it's a term that will show up on internet searches. So here. I'm doing the work for you.
Here is an article on wikipedia describing bigorexia.
Here is an article on About describing bigorexia in a lot more detail.
Here is another article on bigorexia (also called muscle dysmorphia)
Tada. Plus, I'm sure the show tomorrow night will answer some questions as well.