Morbidly obese patients exhibit impaired secretion of satiation hormones which may contribute to the development of obesity. Bariatric surgery is associated with weight loss and dramatic increase in the secretion of satiation hormones, but the underlying mechanism remains unknown. The investigator's goal is therefore to examine patients before and after sleeve gastrectomy and compare findings to lean controls.

Morbidly obese patients exhibit impaired secretion of satiation hormones cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1) and peptide YY (PYY), which may contribute to the development of obesity. Bariatric surgery is associated with weight loss and dramatic increase in the secretion of satiation hormones, but the underlying mechanism remains unknown. A better understanding of mechanisms involved will assist in development of non-invasive therapeutic strategies. The investigator's goal is therefore to examine patients before and after sleeve gastrectomy and compare findings to lean controls. Gastric and intestinal mucosa will be collected by endoscopy from morbidly obese subjects before and 3 months after sleeve gastrectomy. In Addition, lean controls will be examined. Expression of various gut peptides will be assessed by immunohistochemistry and quantitative polymerase chain reaction (PCR).

Inclusion Criteria:

Morbidly obese patients scheduled for sleeve gastrectomy

• BMI > 35 kg/m2
• Age: > 18-65 years Lean, healthy controls
• BMI > 18 and < 28kg/m2
• Age: >18-40 years

Exclusion Criteria:

• Bleeding diathesis
• Previous surgery on the gastrointestinal tract (appendectomy acceptable)