New Year’s just passed and it’s likely that a popular resolution in 2009 is, unsurprisingly, to lose weight.  Well, this year, there is a Facebook app that might make keeping your resolution a little easier.

New Facebook application WeightView allows users to upload a picture of themselves and visualize what they might look like at a new weight.  A “digital photo enhancement” process requires a full body photo and a desired weight loss goal of up to fifty pounds.  WeightView returns a customized photo at the goal weight free of charge.  The idea, of course, is that seeing a thinner, healthier you will motivate you to realize your weight loss goals.

By leveraging Facebook’s social graph, WeightView also provides the same support structure that’s available in traditional weight loss programs like Jenny Craig and Weight Watchers.  It allows its users to meet other group members, earn points towards valuable prizes, and discuss weight loss-related topics with the WeightView community and health care experts.

With over 120k users since its launch, WeightView has already become the most-used weight loss app on Facebook.  One of the company’s founders, Dr. Doran Katz, attributes WeightView’s success to the visualization feature that isn’t offered by most other similar programs, online or offline.

If you’re an avid Facebook user and you’re interested in losing weight in 2009, or, alternatively, if you’re trying to market a weight loss product by piggy-backing on a successful Facebook app, you should check out WeightView.