Hi there! Yes I'm on Optifast 900 and I'm doing okay. It is hard work, like all weigh loss programs are, and it is paying off for me. I noticed that the program seemed to be medically supervised globally, however the program details differ by Country. I'm in Canada and my doc has me on 900 cal/day.
Feel free to add me as a friend and I'll answer as much as I can. Welcome to SP!