Long-term, Substantial Weight Loss and Insulin Regulation of Lipolysis

Inclusion Criteria: * BMI 40 - 50 kg/m2. * Mo active physical illness that would interfere with mobility or weight loss after bariatric surgery Exclusion Criteria: * Type 1 or Type 2 Diabetes diagnosis or fasting plasma glucose ≥126 mg/dL * Active coronary artery disease * Participation in structured exercise (\>2 times per week for 30 minutes or longer) * Smoking * Medications known to affect adipose tissue metabolism (e.g., beta blockers, corticosteroids) * Renal insufficiency (serum creatinine \> 1.5mg/dl) * Chronic active liver disease (Bilirubin \> 17mmol/L, AST \> 144 IU/L, or ALT\>165IU/L) * Pregnancy or breastfeeding.