Inclusion Criteria:  Severe obesity (Body Mass Index (BMI) >/= 120% of the 95th percentile or BMI >/= 35 kg/m2) Age 12 to < 18 years old and Tanner stage >1  Exclusion Criteria:  Diabetes (type 1 or 2) Current or recent (< 6 months prior to enrollment) use of anti-obesity medication(s) defined as orlistat, phentermine, topiramate, combination phentermine/topiramate, liraglutide (or other GLP-1RA) and/or combination naltrexone/bupropion (monotherapy use of naltrexone or bupropion is not an exclusion) Previous bariatric surgery Any history of treatment with growth hormone Medically-documented history of bulimia nervosa Major psychiatric disorder as determined by the local medical monitor Unstable depression requiring hospitalization within the previous 6 month Any history of suicide attempt History of suicidal ideation or self-harm within the previous 30 days Current pregnancy or plans to become pregnant ALT or AST >/= 5 times the upper limit of normal Creatinine > 1.2 mg/dL Uncontrolled hypertension as determined by the local medical monitor Diagnosed and medically-documented monogenic obesity Medically-documented history of cholelithiasis Untreated thyroid disorder Medically documented history of pancreatitis Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2 Clinically significant heart disease as determined by the local medical monitor Personal history of malignant neoplasms within the past five years Hypersensitivity to any component of semaglutide