The purpose of this study is to compare the safety and effectiveness of topiramate (64mg, 96mg, 192mg, and 384mg daily) with placebo in the treatment of obesity.

Topiramate is not approved for the treatment of obesity. This is a randomized, double-blind, placebo-controlled, multicenter study to assess the safety and effectiveness of topiramate in treatment of obese patients. Patients will receive 24 weeks of treatment by topiramate or placebo, followed by 2 week taper and a safety follow-up. Effectiveness will be determined by changes from baseline to week 24 in body weight, body mass index (BMI), anthropometric measurements (waist circumference, hip circumference, waist/hip ration), fasting lipid profiles, fasting plasma glucose, HbA1c (shows average blood sugar level over months), fasting uric acid, fasting insulin, and blood pressures. Safety evaluations (incidence of adverse events, physical examinations, 12 lead ECGs, vital signs, Computerized Neuropsychological Test Battery) will be performed throughout the study. The study hypothesis is that topiramate will be effective in achieving and maintaining weight reduction in obese patients and is well tolerated. The patients will be randomized to receive either topiramate (64, 96, 192, or 384 mg daily) or placebo daily by mouth for 24 weeks.

Inclusion Criteria:

• Body Mass Index (BMI) >=30 and <50
• BMI >= 27 and < 50 if patient has controlled hypertension or abnormal blood lipids
• Stable weight
• Female patients must be postmenopausal for at least 1 year, surgically incapable of childbearing, practicing abstinence, or practicing an acceptable method of contraception (requires negative pregnancy test)

Exclusion Criteria:

• Known contraindication, or hypersensitivity to topiramate
• Exposure to any other experimental drug or device within last 30 days
• A diagnosis of diabetes
• History or evidence of clinically significant liver disease, cardiovascular disease, uncontrolled hypertension or high thyroid levels
• History of obesity with known cause
• History or family history of kidney stones
• History of weight loss surgery
• History of malignancy within last 5 years