A friend of mine has been doing this since fall 2010. It seems like he is one of about 20 team body "coaches" in my area. He is going to a lot of team meetings 2-3 a month. He has changed his life physically. I do not know how much change fiscally though.
From the outside looking in...it seems to me that it requires constant marketing, he is using facebook. I have also seen others market through Craigslist and form groups on meetup.com. There is a lot of constant marketing to friends. I presume you try to get more "coaches" to sign up under your guidance and you get a cut of their sales as well? Not sure of what profit margins there are or volume of sales that can be made.
Smells a whole bunch like MLM to me. For the most part, we don't care too much for MLM around here unless you are the originator of it. The reasons are many.