Effects of Weight Loss Surgery on Bone Health in Adolescents

Inclusion Criteria: 1. Adolescents with morbid obesity 13-25yo undergoing RYGB (n=36) or VSG (n=36), or being followed without surgical intervention (usual care) (n=48). 2. Eligibility criteria for weight loss surgery used at the Weight Center include BMI\>40 or BMI\>35kg/m2 with major comorbidities. A BMI\>35 in adolescents reflects a BMI\>99th percentile. In order to be considered appropriate surgical candidates, children must have a bone age of ≥14y (F) or ≥16y (M), and ≥1 co-morbidity of obesity. They must have demonstrated efforts at non-surgical weight loss, and consistent compliance with appointments and recommendations. Patients must demonstrate sufficient maturity, psychological stability and cognitive capacity to recognize the significance of the procedure and implement required post-operative behavioral changes. Exclusion Criteria: 1. Current pregnancy and breast feeding 2. Medications other than calcium or vitamin D that affect bone, such as glucocorticoids, phenytoin, phenobarbitone (washout of 3 months prior to enrollment if discontinuation is medically permissible) 3. Use of antipsychotic medications that cause weight gain if treated for \<6 mos, or if dosage is not stable for \>2 mos 4. Untreated thyroid dysfunction or on stable dose for \<3 mos 5. HbA1C\>8% (to avoid deleterious effects on bone from uncontrolled T2DM) 6. Smoking \>10 cigarettes/day; substance abuse per Diagnostic and Statistical Manual (DSM) V 7. Metal implants, intracranial surgical clips or pacemakers 8. Weight \>450 lbs due to limits for MRI and CT.