I would say something along the lines of "what's the worst that could happen", but actually, now that I really think about it, that's really not helpful! Given the choice between Godzilla rising out of the North Sea and destroying everything I know and love OR weighing myself in front of people, I'm going to go with the lizard.
That said, friends are good things to have around, because they support and encourage you. Remember, no matter how bad the number is today, next week it's going to be so much better AND you'll have someone else there to a) confirm your eyes aren't lying to you when the smaller number appears b) knock the socks off with your awesome weight-losing powers.
Good luck!