Apart from helping friends stay connected, social networking sites like Facebook and MySpace can also provide moral and nutritional support for people trying to lose weight.
Millions of people using these websites can find useful information, and groups that can help them succeed with their dieting or exercise regime.
"When we embark on a weight loss program we want encouragement, motivation and results. Websites offer so many opportunities to track the sorts of information we know helps keep our weight in check," said Stefanie Barthmare, a licensed professional counselor with The Methodist Weight Management Center in Houston.
She added: "These social networking sites are a perfect place for people to record their progress, find others in the same boat or join weight loss groups. There are also blogs and chat rooms where people can swap recipes, share stories and goals or just offer support."
A recent survey by Nielsen Online found that one in 11 minutes spent online around the world is devoted to social networking and blogging sites.
Barthmare said that blogs also offered another great way for people to find information and support without having to get in your car and go to a meeting.
She said: "When we diet we tend to stick with the same things; the same food, the same support group, etc. This is why many people fall off the wagon a couple of months in."
She added: "It can be motivating to see your friends on one of these sites losing weight. It can push you to work harder and stay focused. The group dynamic when it comes to weight loss is very important and I think these types of sites really offer a new and exciting way for people to connect and support each other their way to a healthier body."