Gastric bypass surgeries for obesity are hypothesized to produce weight loss and improve diabetes by multiple mechanisms including gastric restriction and lower gut stimulation.The surgeries typically involve rearrangement of the fore-gut, hind-gut or both. We compared the effects of foregut (Sleeve Gastrectomy, SG), hindgut (Ileal Transposition; IT), both (SG+IT), or sham manipulations, on food intake, body weight and glucose tolerance in male SD rats. SG, IT and SGIT surgeries produced transient reduction in food intake and weight gain but improvements in glucose tolerance. SG, IT and SGIT surgeries increased plasma GLP-1 concentrations; IT and SGIT increased PYY concentrations. The protein abundance of key markers of glucose metabolism (e.g. GLUT4, AMPK, PKA, IRS-1) in muscle and adipose tissue were increased following SG, IT, or SGIT. Improvement in glycemic control following these surgeries appears to be independent of changes in weight and is likely due to enhanced lower gut stimulation.iii Acknowledgment

Together, our data demonstrate that the reduction in food intake and weight gain, increase in lower gut hormones, glycemic improvements and associated changes in tissue metabolic markers following IT surgery are dependent on the length of the transposed ileum.