As I said, I'm not sure what it's about... at the top of the threads there's an announcement "biggest loser challenge" but I didn't see what it was about, just those signing up.
You are more then welcome to join however all new players will be assigned to an existing team. I believe there are several people that are on/have been on the SBD that participate. Then challenge is open to anyone - just read the posts about it and it'll all make sense.
Hope to see you girls!