As someone who is actively trying to lose weight, I have a slight advantage over most people. With a degree in Human Nutrition, I know the ins and outs of calories, digestion, metabolism, and the entire host of factors that go into successful weight loss. However, the times I have been most successful with my endeavors have been when I participated in either in an in-person group activity or online with a commercial weight loss program. A new study finds that I'm not alone.

Investigators at the Kaiser Permanente Center for Health Research pulled 350 people who had lost at least 19 pounds in six months from a longer-term study of 1600 overweight or obese participants. They designed a weight-loss support website, modeled after Facebook, that tracked weight and exercise over a two-and-a-half year period. Those who failed to log in once a week were followed up with an e-mail or automated phone call encouraging them to enter their information.

The site was designed to mimic (as much as possible) what it is like to be in an in-person weight loss program with personal counseling and group meetings. The study authors found that the combination of keeping participants accountable and providing them with a community helped the participants maintain at least a portion of their weight loss. The more often people logged on, the greater their ability to keep the weight off.

There are many online resources to help you with your weight loss goals. Some require payment while others are free. Kristine Funk, the study's lead author, suggests that when looking for an online program, find one with both a weight tracking feature and a forum for users to interact with each other and experts.

The program that I was successful with is also one of the best known weight loss programs in the world. Weight Watchers offers an online program in addition to its in-person group meetings. The site includes interactive tools to help manage daily food choices and activities and track weight progress. There is also an online community where you can join groups, set challenges and swap recipes. Sign-up fee is $29.95 with a monthly fee thereafter of $17.95, but the site regularly runs specials.

Another popular site is FitDay.com, which offers both a free and a premium paid service for entering daily foods and exercise and tracking weight loss goals. Over 5 million people enjoy membership on FitDay, so the community for support and interaction is strong. You can also purchase a computer software program — FitDay PC v2 — to enter foods and track goals even when you are unable to be online.

If you are on a tight budget and looking for a free community, SparkPeople might be the place for you. Over 8 million people have joined, and company founder Chris Downie ensures the site will remain no charge to help people lose weight and keep it off through personalized diet and fitness plans, message boards, and support teams. SparkPeople was named "Best Health Website" in 2006, 2007, and 2008 by Business Week.

These three sites are by no means the only online resources to help you lose weight and keep it off. But research does show that more people are successful with their efforts when they use tracking tools, such as a diet and exercise journal, and have a support system for both motivation and accountability.