Background Surgery for obesity and metabolic diseases has been evolved in the light of new scientific evidence, long-term outcomes and accumulated experience. EAES has sponsored an update of previous guidelines on bariatric surgery. Methods A multidisciplinary group of bariatric surgeons, obesity physicians, nutritional experts, psychologists, anesthetists and a patient representative comprised the guideline development panel. Development and reporting conformed to GRADE guidelines and AGREE II standards. Results Systematic review of databases, record selection, data extraction and synthesis, evidence appraisal and evidence-todecision frameworks were developed for 42 key questions in the domains Indication; Preoperative work-up; Perioperative management; Non-bypass, bypass and one-anastomosis procedures; Revisional surgery; Postoperative care; and Investigational procedures. A total of 36 recommendations and position statements were formed through a modified Delphi procedure. and Other Interventional Techniques Disclaimer This clinical practice guideline has been developed under the auspice of the European Association for Endoscopic Surgery (EAES). It is intended to be used primarily by health professionals (e.g. surgeons, anesthetists, physicians) and to assist in making informed clinical decisions on diagnostic measures and therapeutic management. It is also intended to inform individual practice of allied health professionals (e.g. surgical nurses, dietitians, physical rehabilitation therapists, psychologists); to inform strategic planning and resource management by healthcare authorities (e.g. regional and national authorities, healthcare institutions, hospital administration authorities); and to inform patients wishing to obtain an overview of the condition of interest and its management. The use of recommendations contained herein must be informed by supporting evidence accompanying each recommendation and by research evidence that might not have been published by the time of writing the present document. Users must thus base their actions informed by newly published evidence at any given point Electronic supplementary material The online version of this article (

OBJECTIVEThis study determined whether the decrease in pancreatic triacylglycerol during weight loss in type 2 diabetes mellitus (T2DM) is simply reflective of whole-body fat or specific to diabetes and associated with the simultaneous recovery of insulin secretory function. RESEARCH DESIGN AND METHODSIndividuals listed for gastric bypass surgery who had T2DM or normal glucose tolerance (NGT) matched for age, weight, and sex were studied before and 8 weeks after surgery. Pancreas and liver triacylglycerol were quantified using inphase, out-of-phase MRI. Also measured were the first-phase insulin response to a stepped intravenous glucose infusion, hepatic insulin sensitivity, and glycemic and incretin responses to a semisolid test meal. RESULTSWeight loss after surgery was similar (NGT: 12.8 6 0.8% and T2DM: 13.6 6 0.7%) as was the change in fat mass (56.7 6 3.3 to 45.4 6 2.3 vs. 56.6 6 2.4 to 43.0 6 2.4 kg). Pancreatic triacylglycerol did not change in NGT (5.1 6 0.2 to 5.5 6 0.4%) but decreased in the group with T2DM (6.6 6 0.5 to 5.4 6 0.4%; P = 0.007). Firstphase insulin response to a stepped intravenous glucose infusion did not change in (P = 0.005). No differential effect of incretin secretion was observed after gastric bypass, with more rapid glucose absorption bringing about equivalently enhanced glucagon-like peptide 1 secretion in the two groups. CONCLUSIONSThe fall in intrapancreatic triacylglycerol in T2DM, which occurs during weight loss, is associated with the condition itself rather than decreased total body fat.Type 2 diabetes mellitus (T2DM) has reached epidemic proportions, affecting 9.2% of the U.S. population and costing the country $322 billion in 2012 (1). The condition is widely recognized to be caused by a combination of insulin resistance and insulin secretory failure. However, insulin resistance alone does not cause blood glucose to rise (2), and T2DM occurs only when the acute insulin response of pancreatic b-cells becomes inadequate to control blood glucose (3,4). The etiologic process underlying this is still uncertain. Inhibition by excess intracellular fatty acids or their metabolites is a potential mechanism (5-7). We have previously demonstrated in people with T2DM that weight loss over 8 weeks can normalize the acute insulin response and

The worldwide obesity epidemic continues unabated, adversely impacting upon global health and economies. People with severe obesity suffer the greatest adverse health consequences with reduced life expectancy. Currently, bariatric surgery is the most effective treatment for people with severe obesity, resulting in marked sustained weight loss, improved obesity-associated comorbidities and reduced mortality. Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), the most common bariatric procedures undertaken globally, engender weight loss and metabolic improvements by mechanisms other than restriction and malabsorption. It is now clear that a plethora of gastrointestinal (GI) tract-derived signals plays a critical role in energy and glucose regulation. SG and RYGB, which alter GI anatomy and nutrient flow, impact upon these GI signals ultimately leading to weight loss and metabolic improvements. However, whilst highly effective overall, at individual level, post-operative outcomes are highly variable, with a proportion of patients experiencing poor long-term weight loss outcome and gaining little health benefit. RYGB and SG are markedly different anatomically and thus differentially impact upon GI signalling and bodyweight regulation. Here, we review the mechanisms proposed to cause weight loss following RYGB and SG. We highlight similarities and differences between these two procedures with a focus on gut hormones, bile acids and gut microbiota. A greater understanding of these procedure-related mechanisms will allow surgical procedure choice to be tailored to the individual to maximise post-surgery health outcomes and will facilitate the discovery of non-surgical treatments for people with obesity.