Little is known about how online social networking can help enhance weight loss. To examine the types of online social support utilized in a behavioral weight loss intervention and relationship of posting and weight loss. A sub-analysis of the content and number of posts to Twitter among participants (n = 47) randomized to a mobile, social network arm as part of a 6-month trial among overweight adults, examining weight loss, use of Twitter, and type of social support (informational, tangible assistance, esteem, network, and emotional support). A number of Twitter posts were related to % weight loss at 6 months (p