Given the prevalence of overweight and obesity, worksite-based health promotion programs have been recommended due to their potential reach and social support impact. Within worksite contexts, many strategies to prevent and treat obesity have focused on educational programs delivered in person or to small groups that target knowledge acquisition and strategies targeted at individuals to improve their dietary and activity practices. These programs have been criticized because they typically reach a small percentage of workers-and seldom those that could benefit most, are of short duration, and have typically small effects that are not sustained. They have also typically been conducted in large worksites that have the greatest resources. The lack of success of these programs may be due to: 1) inadequate intervention intensity, 2) implementation challenges, and 3) a lack of theoretical models as the bases for intervention development. To overcome the limitations of previous research we will conduct a 2 group randomized controlled trial to determine the reach and effectiveness of an extensive intervention that: (a) is based upon sound theory, (b) is delivered primarily through scalable interactive technologies, and (c) leverages the existing organizational and environmental context of the workplace.

This study will test the utility of a social ecological theory, individually-targeted internet-based intervention with monetary incentives to reduce the weight of overweight and obese employees (INCENT) when compared to a low-intensity, internet-based weight loss program without incentives (Livin My Weigh). Participants in INCENT will receive daily e-mail support that facilitates goal setting, regular assessments of body weight, and incentives based on percent of original body weight lost at the end of each quarter over the 12-month program. The e-mail supports will target improving perceptions of self-efficacy and outcome expectations related to weight loss or maintaining a healthy weight. In addition e-mail support will facilitate participant problem solving and identification of resources for healthful eating and physical activity at home, in their neighborhoods, and at their worksite. Participants in Livin My Weigh (LMW)will receive evidence-based physical activity and nutrition information to facilitate weight loss through quarterly newsletters and quarterly educational sessions.

Inclusion Criteria:

• Employed full time at an eligible worksite
• Access to the internet
• BMI > 25

Exclusion Criteria:

• BMI < 25
• no internet access