This is a randomized, double blind, placebo-controlled study of the effects of intranasal oxytocin in youths with obesity, ages 12-18 years old. Subjects will be randomized to receive intranasal oxytocin or placebo (1 spray per nostril, 4 times per day) for 12 weeks. Study visits include screening to determine eligibility, 2-part main study visits at baseline, week 8, and week 12, and safety check-in visits at weeks 1, and 4; phone calls at weeks 2, 6, and 10, with a safety follow-up visit 6 weeks after the last dose of study drug. Study procedures include appetite, behavioral, metabolic, and endocrine assessments.