The primary aim of this study is to compare changes in body weight between an in-person behavioral weight loss program, a technology-based system, and an enhanced version of a technology-based system during a 6 month behavioral weight loss intervention in obese adults. Additional aims will compare changes in body composition, physical activity, dietary intake, and the frequency of self-monitoring of weight loss behaviors between the 3 groups. A total of 84 sedentary, healthy obese adults (BMI: 35.0-45.0 kg/m2) between the ages of 21-55 will be recruited to participate. Assessments will be conducted at 0, 3, and 6 months and will include measurements of height, weight, body composition, blood pressure, physical activity, dietary intake, and eating behaviors. This is a randomized controlled trial in which participants will be randomized after the completion of assessments to one of three groups: standard behavioral weight loss (SBWL), BodyMedia® FIT System (FIT), and BodyMedia® FIT System with Bluetooth® enhancements (FIT-BT). Subjects in SBWL will participate in a behavioral weight loss intervention which includes weekly group sessions throughout the 6 month program. FIT and FIT-BT will not attend weekly group sessions, but will have identical intervention materials mailed each week. FIT will receive the BodyMedia® FIT System, and FIT-BT will receive the BodyMedia® FIT System with Bluetooth® enhancements to use throughout the 6 month program. FIT and FIT-BT will receive a telephone intervention call 1x per month.