Topiramate and Severe Obesity

Inclusion Criteria: * 9-17 years old * Body Mass Index Z-score ≥ 4 SD of French reference * Weight at enrolment ≥ 50 kg * Therapeutic failure \> 6 months * For girls of childbearing age, willing to have an acceptable method of contraception (no estrogens plus progestin) * Negative pregnancy test for girls of childbearing age * Agreeing to participate upon written informed consent * Appropriate understanding of the study Exclusion Criteria: * Syndromic or secondary obesity * Major neurological or psychiatric disorder * Current or history of suicidal thought/attempts * Current or history of breakdown * Previous bariatric surgery * Severe hypercapnia * Renal dysfunction * Deformity in the urinary tract or solitary kidney * History of renal lithiasis or glaucoma * Poorly controlled diabetic children or adolescents (HbA1c \>10%) and diabetic patients treated with Metformine and/or glibenclamide * Hepatic dysfunction * Bicarbonate ≤16 mmol/L * Known hypersensitivity to the active substance or to one of the excipients * Intolerance to saccharose * Enrolment in another therapeutic study * High probability to fail to comply with treatment * Females: Pregnant, planning to become pregnant * No signature on consent form * Uncovered by the French National health Insurance system (Sécurité sociale)