I think you're referring to the Biggest Loser challenge going on in the 20-somethings forum. It's just a weight loss challenge they have going on for a few weeks. The colors don't denote anything other than different teams.
__________________ Jaime :: Blog
"We are all inventors, each sailing out on a voyage of discovery, guided each by a private chart, of which there is no duplicate. The world is all gates, all opportunities." Ralph Waldo Emerson
To add to the confusion, there are usually Biggest Loser challenges going on down in the exercise forum... there's one right now, but I just looked and I think there's only red and blue teams.