Early Re-Initiation of Semaglutide Post Sleeve Gastrectomy in Youth

Inclusion Criteria: * ages 12 to 18 years * Tanner stage 3 or higher * severe obesity (defined as a BMI greater than 35 kg/m2 or BMI ≥140% of the 95th percentile) * currently undergoing primary surgical weight loss through the pediatric bariatric surgery pathway at Children's Hospital Los Angeles * be willing to have blood collected before and after surgical procedure at defined points * be willing to have clinical data entered into a prospective database; 8) presence of a consenting caregiver * be taking semaglutide 2.4 mg weekly as part of their routine medical care prior to surgery as part of their obesity treatment program, apart from any planned surgical procedure. Exclusion Criteria: * have a previous diagnosis of type 1 diabetes * taking any medications known to influence body composition or prevent weight loss or promote weight gain (e.g. prednisone) * have been diagnosed with syndromes or diseases that may influence the postoperative course (e.g., Cushing syndrome, Down syndrome, Prader Willi Syndrome) * have significant comorbid medical conditions necessitating frequent hospitalization that may require interruption of medications and/or that would make early re-initiation of semaglutide unsafe due to the other medical comorbidities * refuse to comply with eligibility criteria.