The investigators wish to study the effects of three forms of bariatric surgery: Roux-en-Y gastric bypass, Sleeve Gastrectomy, and Gastric Banding. The surgery is not part of the clinical trial. If your insurance does not cover the procedure, then you are responsible for payment of the surgical process. We are doing pre and post surgery testing to provide a better understanding of the effect of bariatric surgery-induced weight loss on metabolic function.

Bariatric surgery is the most effective weight loss therapy for obesity. Moreover, the early improvement in insulin sensitivity and the resolution of type 2 diabetes after bariatric surgery has led to the hypothesis that bariatric surgery has specific beneficial effects on glucose homeostasis beyond weight loss alone. However, this hypothesis has never been adequately evaluated in human subjects. Therefore, the primary goal of this proposal is to provide a better understanding of the effect of bariatric surgery-induced weight loss on insulin action and pancreatic beta cell function.

Inclusion Criteria:

• BMI ≥ 35 kg/m²
• on stable dose of medications for at least 4 weeks before the pre-surgery metabolic studies

Exclusion Criteria:

• smokes > 7 cigarettes per day
• previous malabsorptive or restrictive intestinal surgery
• pregnant or breastfeeding
• recent history of neoplasia (< 5 years ago)
• have malabsorptive syndromes and inflammatory intestinal disease
• diabetes mellitus
• show signs of oral disease or xerostomia (i.e., dry mouth)
• history of chronic rhinitis
• on medication that might affect metabolism
• severe organ dysfunction

A total of 20 (per surgical group) morbidly obese (BMI ≥ 35 kg/m²) subjects scheduled for bariatric surgical procedures will participate in this study.