This randomized controlled trial is designed to determine whether weight losses in a group behavioral weight loss intervention conducted over the Internet are increased with the inclusion of individual, online MI sessions. All participants will receive the same online 6-month group-based behavioral weight loss program followed by 12 months of weight maintenance. Overweight and obese adults at two study sties (N=426) will be randomized to (1) Internet intervention; or 2) Internet intervention with individual MI sessions occurring at three month intervals on a fixed schedule (Internet+MI-Fixed). Assessments will be conducted every six months and will include measures of body weight and height, diet and exercise behaviors, Quality of Life, adherence measures (eg., attendance, compliance with self-monitoring), social influence components, motivation, treatment satisfaction, demographic data and descriptive information regarding use of website components. A third arm was added for the final 3 intervention cohorts. All participants received the program as described above with the addition of motivational interviewing contingent on participants' attendance in classes.
