Obesity is an escalating global chronic disease. Bariatric surgery is a very efficacious treatment for obesity and its comorbidities. Alterations to gastrointestinal anatomy during bariatric surgery result in neurological and physiological changes affecting hypothalamic signaling, gut hormones, bile acids, and gut microbiota, which coalesce to exert a profound influence on eating behavior. A thorough understanding of the mechanisms underlying eating behavior is essential in the management of patients after bariatric surgery. Studies investigating candidate mechanisms have expanded dramatically in the last decade. Herein we review the proposed mechanisms governing changes in eating behavior, food intake, and body weight after bariatric surgery. Additive or synergistic effects of both conditioned and unconditioned factors likely account for the complete picture of changes in eating behavior. Considered application of strategies designed to support the underlying principles governing changes in eating behavior holds promise as a means of optimizing responses to surgery and long-term outcomes.

Background:Roux-en-Y gastric bypass (RYGB) surgery is currently the most effective treatment of obesity, although limited by availability and operative risk. The gut hormones Glucagon-like peptide-1 (GLP-1), Peptide YY (PYY), and Oxyntomodulin (OXM) are elevated postprandially after RYGB, which has been postulated to contribute to its metabolic benefits.Objective:We hypothesized that infusion of the three gut hormones to achieve levels similar to those encountered postprandially in RYGB patients might be effective in suppressing appetite. The aim of this study was to investigate the effect of a continuous infusion of GLP-1, OXM, and PYY (GOP) on energy intake and expenditure in obese volunteers.Methods:Obese volunteers were randomized to receive an infusion of GOP or placebo in a single-blinded, randomized, placebo-controlled crossover study for 10.5 hours a day. This was delivered subcutaneously using a pump device, allowing volunteers to remain ambulatory. Ad libitum food intake studies were performed during the infusion, and energy expenditure was measured using a ventilated hood calorimeter.Results:Postprandial levels of GLP-1, OXM, and PYY seen post RYGB were successfully matched using 4 pmol/kg/min, 4 pmol/kg/min, and 0.4 pmol/kg/min, respectively. This dose led to a mean reduction of 32% in food intake. No significant effects on resting energy expenditure were observed.Conclusion:This is, to our knowledge, the first time that an acute continuous subcutaneous infusion of GOP, replicating the postprandial levels observed after RYGB, is shown to be safe and effective in reducing food intake. This data suggests that triple hormone therapy might be a useful tool against obesity.

Background: Obesity surgery is effective for obesity and type 2 diabetes (T2DM). However, many patients do not achieve sustained diabetes remission following surgery. Liraglutide, a GLP-1 analogue, improves glycaemia and reduces body weight. Our aim was to evaluate the safety and effectiveness of Liraglutide 1•8 mg in patients with persistent or recurrent T2DM after surgery. Methods: In this double-blind, placebo-controlled trial, adults with HbA1c >48 mmol/mol (>6•5%) at least one year after surgery were randomised 2:1 to once-daily subcutaneous Liraglutide 1•8 mg or Placebo, together with a reduced-calorie diet and increased physical activity. The primary outcome was the change in HbA1c from baseline to 26 weeks. EudraCT 2014-003923-23 and ISRCTN 13643081. Findings: Between February 2016 and November 2018, we assigned 80 patients to receive Liraglutide (n=53) or Placebo (n=27). Seventy-one (89%) participants completed the study up to week 26 (complete-cases population). A multivariable linear regression analysis taking baseline HbA1c and type of surgery into account as covariates showed that Liraglutide was associated with a difference in HbA1c change of-13•3 mmol/mol or-1•22%, 95% CI-19•7 to-7•0, p<0•001) vs Placebo at 26 weeks. Liraglutide was associated with a difference in the change of weight of-4•23 kg [95% CI-6•81 to-1•64, p<0•001) vs Placebo. No significant influence of type of surgery was noted. Interpretation: This is the first randomised controlled trial of adjunctive Liraglutide treatment in patients with diabetes mellitus after metabolic surgery. The results support the use of Liraglutide therapy in this clinical context. Funding: JP Moulton Charitable Foundation 3 surgery. We have previously shown that the acute peripheral administration of the GLP-1 RA Exendin-4 in rodent models of RYGB has additive effects to the already enhanced endogenous GLP-1 secretion as demonstrated by an additional reduction in food intake 11. Indeed, data from retrospective non-randomised studies in humans support this hypothesis: the administration of GLP-1 RAs in patients with and without T2DM and a suboptimal response to metabolic surgery was associated with weight loss and glycaemic improvements 12-15. This RCT was therefore designed to investigate the safety and efficacy of pharmacological administration of the GLP-1 RA Liraglutide on glycaemic control in patients with persistent or recurrent T2DM after RYGB or VSG surgery. Methods Study population This was a prospective randomised double-blinded placebo-controlled clinical trial. Eighty patients with obesity and persistent or recurrent T2DM that had undergone RYGB or VSG surgery at least 12 months before randomisation were recruited from the

Objective: The aim of this study was to examine the clinical efficacy and safety of the duodenal-jejunal bypass liner (DJBL) while in situ for 12 months and for 12 months after explantation. Summary Background Data: This is the largest randomized controlled trial (RCT) of the DJBL, a medical device used for the treatment of people with type 2 diabetes mellitus (T2DM) and obesity. Endoscopic interventions have been developed as potential alternatives to those not eligible or fearful of the risks of metabolic surgery. Methods: In this multicenter open-label RCT, 170 adults with inadequately controlled T2DM and obesity were randomized to intensive medical care with or without the DJBL. Primary outcome was the percentage of participants achieving a glycated hemoglobin reduction of ≥20% at 12 months. Secondary outcomes included weight loss and cardiometabolic risk factors at 12 and 24 months. Results: There were no significant differences in the percentage of patients achieving the primary outcome between both groups at 12 months [DJBL 54.6% (n = 30) vs control 55.2% (n = 32); odds ratio (OR) 0.93, 95% confidence interval (CI): 0.44–2.0; P = 0.85]. Twenty-four percent (n = 16) patients achieved ≥15% weight loss in the DJBL group compared to 4% (n = 2) in the controls at 12 months (OR 8.3, 95% CI: 1.8–39; P = .007). The DJBL group experienced superior reductions in systolic blood pressure, serum cholesterol, and alanine transaminase at 12 months. There were more adverse events in the DJBL group. Conclusions: The addition of the DJBL to intensive medical care was associated with superior weight loss, improvements in cardiometabolic risk factors, and fatty liver disease markers, but not glycemia, only while the device was in situ. The benefits of the devices need to be balanced against the higher rate of adverse events when making clinical decisions. Trial Registration: ISRCTN30845205. isrctn.org; Efficacy and Mechanism Evaluation Programme, a Medical Research Council and National Institute for Health Research (NIHR) partnership reference 12/10/04.

Long-term reductions in the quantity of food consumed, and a shift in intake away from energy dense foods have both been implicated in the potent bariatric effects of Roux-en-Y gastric bypass (RYGB) surgery. We hypothesised that relative to pre-operative assessment, a stereotypical shift to lower intake would be observed at a personalised ad libitum buffet meal 24 months after RYGB, driven in part by decreased selection of high energy density items. At pre-operative baseline, participants (n = 14) rated their preference for 72 individual food items, each of these mapping to one of six categories encompassing high and low-fat choices in combination with sugar, complex carbohydrate or and protein. An 18-item buffet meal was created for each participant based on expressed preferences. Overall energy intake was reduced on average by 60% at the 24-month buffet meal. Reductions in intake were seen across all six food categories. Decreases in the overall intake of all individual macronutrient groups were marked and were generally proportional to reductions in total caloric intake. Patterns of preference and intake, both at baseline and at follow-up appear more idiosyncratic than has been previously suggested by verbal reporting. The data emphasise the consistency with which reductions in ad libitum food intake occur as a sequel of RYGB, this being maintained in the setting of a self-selected ad libitum buffet meal. Exploratory analysis of the data also supports prior reports of a possible relative increase in the proportional intake of protein after RYGB.

Background & aims: Duodenal-jejunal bypass liners (DJBLs) prevent absorption in the proximal small intestine, the site of fatty acid absorption. We sought to investigate the effects of a DJBL on blood concentrations of essential fatty acids (EFAs) and bioactive polyunsaturated fatty acids (PUFAs). Methods: Sub-study of a multicentre, randomised, controlled trial with two treatment groups. Patients aged 18e65 years with type-2 diabetes mellitus and body mass index 30e50 kg/m 2 were randomised to receive a DJBL for 12 months or best medical therapy, diet and exercise. Whole plasma PUFA concentrations were determined at baseline, 10 days, 6 and 11.5 months; data were available for n ¼ 70 patients per group. Results: Weight loss was significantly greater in the DJBL group compared to controls after 11.5 months: total body weight loss 11.3 ± 5.3% versus 6.0 ± 5.7% (mean difference [95% CI] ¼ 5.27% [3.75, 6.80], p < 0.001). Absolute concentrations of both EFAs, linoleic acid and a-linolenic acid, and their bioactive derivatives, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid, were significantly lower in the DJBL group than in the control group at 6 and 11.5 months follow-up. Total serum cholesterol, LDL-cholesterol and HDL-cholesterol were also significantly lower in the DJBL group. Conclusion: One year of DJBL therapy is associated with superior weight loss and greater reductions in total serum cholesterol and LDL-cholesterol, but also depletion of EFAs and their longer chain derivatives. DJBL therapy may need to be offset by maintaining an adequate dietary intake of PUFAs or by supplementation. Trial registration: ClinicalTrials.gov Identifier NCT02459561.

Obesity is associated with an increased preference for sweet and high-fat foods, and the most consistent evidence has been the shift away from these calorie-dense foods in both animal and human studies after RYGB. Self-reporting is the most common method used to record food preferences in humans, while more direct approaches have been used in animal work. This methodological heterogeneity may give rise to inconsistent findings. Future studies in humans should focus on direct measures to permit corroboration of mechanistic insights gained from animal studies.

Background and Aims: Bariatric surgery is the most effective treatment for obesity. however, not all patients have similar weight loss following surgery and many researchers have attributed this to different pre-operative psychological, eating behavior, or quality-of-life factors. the aim of this study was to determine whether there are any differences in these factors between patients electing to have bariatric surgery compared to less invasive nonsurgical weight loss treatments, between patients choosing a particular bariatric surgery procedure, and to identify whether these factors predict weight loss after bariatric surgery.Material and Methods: this was a prospective study of 90 patients undergoing gastric bypass, vertical sleeve gastrectomy, or adjustable gastric banding and 36 patients undergoing pharmacotherapy or lifestyle interventions. all patients completed seven multi-factorial psychological, eating behavior, and quality-of-life questionnaires prior to choosing their weight loss treatment. Questionnaire scores, baseline body mass index, and percent weight loss at 1 year after surgical interventions were recorded.Results and Conclusions: surgical patients were younger, had a higher body mass index, and obesity had a higher impact on their quality of life than on non-surgical patients, but they did not differ in the majority of eating behavior and psychological parameters studied.