Phentermine/Topiramate as Preventive Pharmacotherapy for Obesity

This study will evaluate the effects of preventative pharmacotherapy on body mass index (BMI), as well as incidence of obesity and normal weight, in adolescents at high risk of developing obesity. We hypothesize that 24 months of Qsymia vs. placebo, in combination with lifestyle-based weight gain prevention coaching, will prevent increases in BMI (primary endpoint). More participants in the placebo group will develop obesity (cross the BMI 30 kg/m2 threshold) and more in the Qsymia group will transition to normal weight (drop below a BMI of 25 kg/m2). All participants, regardless of medication/placebo assignment, will receive the same foundational weight gain prevention coaching throughout the entire study. The weight gain prevention coaching will be delivered individually by master's level behavioral intervention specialists with expertise in nutrition, physical activity, and weight-related behavior change. The multi-phase prevention intervention will start with 6 weekly 30-minute coaching calls followed by monthly 15-minute check-in calls for the remainder of the first year. At the beginning of the second year, a series of 3, 30-minute coaching calls will be held to revisit the information covered in the initial coaching calls, followed by bi-monthly 15-minute check-in calls for the remainder of the second year. The calls will be conducted via videoconference substituted with phone calls if needed. The weight gain prevention intervention will utilize empirically supported behavior change strategies to help promote healthy dietary intake, physical activity patterns, and modest weight loss and/or prevent weight gain among participants. The intervention is informed by several of our previous weight loss and maintenance trials and the work of others, including weight gain prevention trials in young adult populations. The core prevention intervention is based on a behavioral conceptualization of effective weight management that emphasizes: 1) identifying behaviors in need of change; 2) setting goals for change; 3) monitoring progress; 4) modifying environmental cues to facilitate change; and 5) modifying consequences to motivate change. The intervention will incorporate core behavior change strategies including self-monitoring, stimulus control, modeling, goal setting, and positive reinforcement, which were among the common behavior change elements identified across the 17 treatment arms used in the Early Adult Reduction of weight through LifestYle (EARLY) weight management trials that included the young adult weight gain prevention trials previously referenced.