I have been around for awhile on the SparkPeople community -- and I can tell you from my personal viewpoint -- it works! I am in this age group, and I need to be accountable. The SparkPeople community has the support and vetted tools to make this possible. www.sparkpeople.com/resource/motivation_ar
The above link is for a Study: Socializing on SparkPeople Helps with Weight Loss. Not only does it detail why it helps with weight loss, the link details how to go about doing it, how to get the kind of support that will get you through the tough times, the plateaus that inevitably happen on the weight loss journey. Using a different weight loss provider, I was on a plateau of 8 weeks before there was action on the scale. That's a long time when you are paying a fee every week. Here at SparkPeople you don't have to pay with your money - (unless you want to use SparkCoach, which i happen to do) - just spend the time, and allow yourself to get informed in a way that makes sense to you.
If you need some help getting started with the SparkPeople website, this link may be helpful: www.sparkpeople.com/myspark/get_started.as
Best wishes all, for meeting your goals in 2013.