Phentermine/Topiramate as Preventive Pharmacotherapy for Obesity

This study will test the use of phentermine and topiramate compared with placebo in helping adolescents who are at high risk for developing obesity to lose weight

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.

Eligibility Criteria:
Inclusion Criteria:

* Age 16 to less than 22 years at screening
* BMI \>/= 25 to \< 30 kg/m\^2
* Family history of obesity defined as one biological parent with severe obesity (BMI \>/= 35) and/or two biological parents with obesity (BMI \>/= 30)
* Age 16 or 17 years old must also have an obesity-related complication/co-morbidity defined as elevated blood pressure (\>/= 130 and/or \>/= 80 milligrams of mercury \[mmHg\]) or current use of anti-hypertensive medication, dyslipidemia (triglycerides \>/= 150 milligrams/deciliter (mg/dL) and/or HDL cholesterol \< 40 mg/dL or current use of cholesterol-lowering medication, diagnosis of obstructive sleep apnea

Exclusion Criteria:

* Tanner stage 1-4
* Diabetes (1 or 2)
* Current or recent (\< 6 months prior to enrollment) use of anti-obesity medication(s) and other weight-altering medication(s) (e.g.,, atypical antipsychotics, attention-deficit hyperactivity disorder \[ADHD\] stimulant)
* Previous bariatric surgery
* Current or recent (\< 6 months prior to enrollment) use of medication(s) to treat insulin resistance
* Recent initiation (\< 3 months prior to enrollment) of anti-hypertensive or lipid medication(s)
* History of glaucoma
* Current or recent (\< 14 days) use of monoamine oxidase inhibitor
* Known hypersensitivity to sympathomimetic amines
* History of treatment with growth hormone
* Patient Health Questionnaire (PHQ) score of \>/= 15
* Eating disorder symptoms within 6 months and/r any past medical diagnosis of eating disorder
* Major psychiatric disorder
* Unstable clinically-diagnosed depression
* History of suicide attempt
* Suicidal ideation of type 4 or 5 on the Columbia-Suicide Severity Rating Scale (C-SSRS) in the last month
* Current pregnancy or breastfeeding
* Plans to become pregnant
* If sexually active, refusal to use 2 forms of birth control
* Tobacco use
* Alanine transaminase (ALT ) or Aspartate transaminase (AST) \>/= 2.5 the upper limit of normal
* Bicarbonate \< 18 micromoles per liter (mmol/L)
* Creatinine 1.2 mg/dL
* Creatinine clearance of \< 50 microliters per minute \[mL/min\] (Schwartz formula)
* History of seizures
* Uncontrolled hypertension
* History of structural heart defect
* History of clinically significant arrhythmia
* Diagnosed monogenic obesity
* History of cholelithiasis
* History of nephrolithiasis
* Hyperthyroidism
* Untreated thyroid disorder