Accountability is the best way to describe WW. If you go to the meetings knowing you have to weigh in, there is a better chance you will stay strick or true to your eating choices. I know on weigh in days I wasn't always ready for the results but the results are there whether you're ready or not.
My first week I lost 8 pounds which was a great motivator to keep going. Of course, as the weeks went on, the pounds settled out to 2 or 3 pounds a week. Even so, I was successful on WW, but gained the weight back after pregnancy, etc. It's been 9 years since that WW visit.