This two site study will evaluate the safety and effectiveness of laparoscopic truncal vagotomy for the treatment of obesity with baseline study and 18 month post op follow up.

30 morbidly obese patients evenly enrolled at The University of California San Francisco and at the University of Rochester will be selected for study on a voluntary basis. They will have a BMI of >35 with at least one obesity related comorbidity or a BMI between 40 and 45. Subjects will undergo specific tests of vagal function and baseline metabolic evaluation at baseline.

Thereafter they will undergo a laparoscopic truncal vagotomy. Over 18 months, post operative tests of adequate vagotomy, weight loss, change in body composition and metabolism will be studied.

Inclusion Criteria:

• male or female age 25-55
• BMI 35-40 with comorbidity and BMI 40-45 with or without comorbidity
• Stable weight for the last 3 months
• willing to use contraceptives
• motivated to lose weight
• a personal history of at least one professionally supervised 6 month attempt or more than 2 serious attempts to loose weight
• fully ambulatory

Exclusion Criteria:

• sign of prior major abdominal surgery
• history of or signs and /or symptoms of gastro-duodenal ulcer disease
• abnormal vagus nerve testing
• current use of a list of medication