Weight gain accelerates during early adulthood, and leads to the health consequences of obesity (high blood pressure, diabetes, heart disease, etc). Most weight loss studies enroll middle-aged adults. This study tests the hypothesis that a weight loss intervention that builds on prior research evidence but is enhanced with technological innovations will lead to weight loss in a diverse group of overweight and obese adults aged 18-35 years. The technology intervention, using cell phone applications, will be compared to an "advice only" control group and to a group receiving a more traditional personal coaching intervention.

Trials in middle aged adults indicate that weight loss can be achieved and sustained with frequent contact over a long period of time, frequent self-monitoring, social support and motivational counseling. However, it is unclear whether this strategy would work in younger adults. Based on life stage, cultural context, environmental circumstances, and marketing pressures, behavioral intervention may need to be substantially modified to be effective in young adults. Even more adaptation will be required for intervention to be effective in young adults from racial/ethnic minority groups. The proposed intervention builds on prior evidence with innovations directed at increasing effectiveness in young adults.

Using cell phones to deliver a weight control intervention in this age group has the potential to be engaging, enjoyable, practical, cost-effective, sustainable, and broadly disseminated. We propose a trial in which a highly innovative but more risky intervention based almost entirely on use of cell phone technology and a second more incremental innovation over traditional behavioral intervention are each compared to a usual care control group. We will recruit a diverse target population of overweight/obese, generally healthy young adults, comprising approximately 35% non-Latino Whites, 35% non-Latino Blacks, and 30% Latinos, to be randomized to: 1) Usual care control: Educational materials and information but no behavioral intervention; 2) Cell-phone intervention: similar education and knowledge as the control group, but thereafter a behavioral intervention will be delivered almost exclusively via cell phone, particularly using the self-monitoring and social networking features of this technology; 3) Personal contact with cell-phone enhancement: personal contact intervention enhanced by cell-phone for self-monitoring.

The post-randomization intervention period will last 24 months. The primary outcome is change in weight 12 months post-randomization; an important secondary outcome is weight change at 24 months.

The formative phase will focus largely on technology/intervention development.

To assess maintenance of weight loss, after completion of the primary outcome assessment (24 months post-randomization), participants in the control group are followed observationally; those in the cell-phone and personal coaching interventions are re-randomized to either continue intervention or stop intervention with observational follow-up. All participants who agree to participate in this maintenance phase are followed for an additional 2-3 years with data collection every 6-12 months.

Inclusion Criteria:

• Age 18-35 years;
• BMI >=25;
• Using a cellphone.

Exclusion Criteria:

• Diabetes mellitus;
• Pregnant or nursing;
• Use of weight loss medications, systemic steroids, antipsychotics, or diabetes medication;
• Prior weight loss surgery;
• Cardiovascular (CVD) event in past 6 months;
• Current malignancy.

24 months