Changes in Insulin Sensitivity After Weight Loss

This study is designed to compare the changes in insulin sensitivity as well as gastrointestinal hormone levels in diabetic and non-diabetic obese individuals who are undergoing weight loss procedures. The main hypothesis of this study is that weight loss induced by gastric bypass will induce a greater improvement in insulin sensitivity compared with gastric banding or low calorie diet. Subjects will be studied before and after weight loss. Studies consist of intravenous glucose tolerance test, body composition analysis, meal test, and energy expenditure.