My group at work is doing a biggest loser challenge, and I'm currently in 1st place! It's definitely tough though. 2nd, 3rd, and 4th place are all guys who have a decent amount of weight to lose, and seem to be losing much easier. I lost a bunch of water weight in the beginning, so I'm down 10.8 pounds and 5.96% from my starting weight.
The contest is for 8 weeks, we're currently 4 weeks in, and is by percentage of weight lost.
Wish me luck! It's definitely motivation to weigh in with your coworkers every week, certainly helps keep me on track.