Meal Disposal After Bariatric Surgery

The meal disposal after bariatric surgery can change depending on the surgical procedures, it is influenced by the gastrointestinal rearrangement and by its functional adaptation to the new anatomical condition. Roux-en Y Gastric Bypass (RYGB), considered a restrictive and malabsorptive technique, is characterised by a rapid delivery of food into the jejunum that contributes to a rapid appearance of glucose in peripheral circulation and hormonal adaptations. Thus post meal increase of insulin secretion, increased glucagon-like peptide-1 and gastric inhibitory polypeptide, paradoxical increase of glucagon and reduced suppression of endogenous glucose production contribute to the post meal glycaemic pattern observed and characterised from an initial increase in plasma glucose levels followed by a sharp drop. Furthermore, after RYGB, protein digestion and amino acid absorption appear to be accelerated. A reduction of postprandial triglyceride concentrations is observed, suggesting reduced lipid absorption or increased clearance. Biliopancreatic diversion (BPD), an example of malabsorptive technique, is characterised by major metabolic improvements. BPD determines an important amelioration of insulin sensitivity with a reduction of plasma glucose. However, on the contrary of RYGB, postprandial glycaemic time-course is not influenced. Furthermore, after BPD, the absorption of proteins and, especially, lipids is reduced.