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Objective: This pilot study tested whether an Internet-based intervention could achieve change in fruit, juice, and vegetable consumption, physical activity, and self-efficacy in youth at-risk of obesity., Method: Participants were 80 8-to-10-year-old African American girls at-risk of obesity, with a home computer, Internet access, and an e-mail address. A two-group design was followed. Groups differed only on incentive schedule (immediate, delayed). The 8-week home-based program, conducted entirely over the Internet, promoted fruit, juice, vegetables, and water intake and physical activity. Pre-post measures were collected through self-report via the program website. The study was conducted in the greater Houston, TX, area September through November, 2004., Results: Statistically significant pre-to-post differences were observed in fruit, juice, and vegetable consumption (p=.002), physical activity--yesterday (p<.001), physical activity--usually (p=.001), and fruit, juice, and vegetable self-efficacy (p=.003)., Conclusion: Internet-based obesity prevention programs may be an effective channel for promoting healthy diet and physical activity behaviors to youth at-risk of obesity. Additional research is needed to more fully examine their effectiveness at promoting and maintaining diet and physical activity change.

Internet-based interventions hold promise as an effective channel for reaching large numbers of youth. However, log-on rates, a measure of program dose, have been highly variable. Methods to enhance log-on rate are needed. Incentives may be an effective method. This paper reports the effect of reinforcement schedule and recruitment method on log-on rates to an 8-week Internet-based obesity prevention program. It also explores trends in log-on rate. Girls were randomized to receive immediate (weekly) or delayed (program end) incentives ($5). The study was powered to detect a moderate-to-large effect (0.65). Overall log-on rate was 74.5%. A higher but not statistically different log-on rate was observed in the immediate incentive group (79%) than in the delayed incentive group (70%) (P = 0.118), and among girls recruited via media (80%) as opposed to non-media methods (69%) (P = 0.058). Trend analysis indicated a significant drop in log-on rate between weeks 4 and 5 among all participants (P = 0.009). Although an acceptable log-on rate was achieved in this program, there was a substantial drop between weeks 4 and 5. Identifying the reason that this occurred may provide insight into how to further enhance log-on rate. Recruitment method may influence log-on rate.