Continuing Education Activity

Obesity is a chronic, progressive, relapsing disease that affects more than 40% of adults and contributes to numerous metabolic, cardiovascular, respiratory, musculoskeletal, oncologic, and psychosocial complications. As understanding of obesity has evolved, metabolic and bariatric surgery has emerged as the most effective and durable treatment for eligible patients, offering sustained weight loss, improvement or remission of obesity-related comorbidities, and reductions in long-term mortality. This course reviews updated indications, expanded procedural options, and advances in perioperative care that have further strengthened the role of surgery in comprehensive obesity management. Participants will gain an understanding of patient selection for surgical therapies for the treatment of severe obesity, current guidelines for preoperative evaluation, contemporary bariatric and endoscopic procedures, mechanisms of metabolic benefit, postoperative management, expected clinical outcomes, and potential complications. This activity for healthcare professionals is designed to enhance learners' competence in performing evidence-based counseling, making individualized treatment decisions, and implementing an appropriate interprofessional approach when managing obesity to optimize long-term patient outcomes.

Objectives:

• Identify current evidence-based indications for bariatric surgery.
• Apply guideline-directed preoperative evaluation strategies.
• Select appropriate bariatric interventions tailored to individual patient factors.
• Collaborate with interprofessional team members to improve care coordination and outcomes for patients with severe obesity undergoing surgical treatment.

Access free multiple choice questions on this topic.

Introduction

Obesity is a chronic, progressive, relapsing disease and a significant public health challenge associated with rising healthcare costs. The prevalence among adults has reached 40.3%, including 9.7% with severe obesity, while an additional 31.7% are classified as overweight.[1] Obesity is characterized by excessive accumulation of adipose tissue that increases the risk of medical complications and diminishes quality of life. Body mass index (BMI), calculated as weight in kilograms divided by height in meters squared, is the standard metric for classification. According to the World Health Organization (WHO), obesity is defined as a BMI of 30 kg/m² or more, whereas overweight corresponds to a BMI between 25 and 29.9 kg/m²

Beyond its effects on physical health, obesity also exerts substantial psychosocial and economic effects. It is an established risk factor for more than 50 comorbid conditions, including type 2 diabetes, hypertension, dyslipidemia, nonalcoholic fatty liver disease, cardiovascular disease, obstructive sleep apnea, osteoarthritis, chronic kidney disease, various cancers, and depression.[1] In 2019, the global economic burden of obesity ranged from $3.19 billion in low-income countries to $1.33 trillion in high-income nations, with the United States alone incurring an estimated $126 billion in 2022.[2][3]

Management of obesity encompasses lifestyle modification, pharmacologic therapy, and surgical intervention. Behavioral strategies that promote dietary changes and increased physical activity often yield modest and short-term results. Pharmacologic advances, particularly with glucagon-like peptide-1 receptor agonists(GLP-1 RAs), have transformed medical therapy for obesity; however, metabolic and bariatric surgery (MBS) remains the most effective, durable, and cost-efficient treatment modality.[4][5] Despite its proven safety and efficacy, less than 1% of eligible individuals undergo MBS, largely due to limited understanding of obesity as a chronic disease, lack of awareness of surgical benefits, and persistent apprehension toward operative interventions.[6]

Issues of Concern

Indications for Metabolic and Bariatric Surgery

In 2022, the American Society for Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) jointly revised the indications for metabolic and bariatric surgery, updating and superseding the 1991 National Institutes of Health (NIH) guidelines.[7]

These updated recommendations provide the following guidance:

• MBS is indicated for individuals with a BMI ≥35 kg/m², irrespective of the presence, absence, or severity of obesity-related complications.
• MBS is recommended for individuals with a BMI between 30–34.9 kg/m² who have type 2 diabetes or other significant obesity-associated medical conditions.
• MBS may be considered in individuals with a BMI of 30–34.9 kg/m² who do not achieve adequate weight reduction or improvement in comorbidities through nonsurgical interventions.

Among Asian populations, anthropometric differences justify the recognition of clinical obesity at a BMI threshold of 25 kg/m² or more, prompting the use of lower BMI cut-offs when evaluating surgical candidacy. No absolute age restrictions for bariatric procedures have been established; however, candidate selection should include a comprehensive evaluation, including frailty assessment, particularly for elderly patients.

Approved Surgical Procedures and Devices

The following procedures are recognized and approved by the ASMBS and the IFSO:

• Roux-en-Y gastric bypass (RYGB)
• Sleeve gastrectomy
• Adjustable gastric banding (AGB)
• Biliopancreatic diversion with duodenal switch (BPD-DS)
• Single anastomosis duodenoileal bypass with sleeve gastrectomy (SADI-S)
• One anastomosis gastric bypass (OAGB)
• Bariatric reoperative procedures
• Endoscopic techniques, including endoscopic sleeve gastroplasty (ESG) and intragastric balloons

Sleeve gastrectomy and Roux-en-Y gastric bypass remain the predominant metabolic and bariatric surgical procedures, representing approximately 60% and 20% of all operations, respectively. Revisional procedures account for an additional 10%, with other surgical approaches comprising the remaining proportion. Utilization of adjustable gastric banding has steadily declined over recent years, whereas procedures, eg, BPD-DS, SADI-S, and OAGB have shown a gradual upward trend in practice.

Preoperative Evaluation for Metabolic and Bariatric Surgery

The selection of an appropriate bariatric procedure is guided by the patient’s individual goals, preferences, available surgical expertise, and a risk–benefit assessment that emphasizes safety and long-term outcomes. Comprehensive preoperative evaluation is essential to optimize patient selection and reduce perioperative complications.[8]

• Clinical assessment: A complete history and physical examination should focus on obesity-related comorbidities, etiologic factors contributing to weight gain, historical weight trends, and the patient’s motivation for sustained lifestyle modification.
• Cardiopulmonary evaluation: All candidates should undergo preoperative cardiopulmonary assessment, with noninvasive cardiac testing performed when indicated in accordance with the most recent American College of Cardiology/American Heart Association (ACC/AHA) perioperative cardiovascular evaluation guidelines. Screening for obstructive sleep apnea is recommended, with formal pulmonary testing if clinically warranted.
• Thromboembolic risk assessment: Patients with a history of deep vein thrombosis (DVT) should be evaluated for active disease, and perioperative anticoagulation strategies should be individualized based on thromboembolic risk.
• Psychosocial and behavioral evaluation: A comprehensive psychological evaluation, ideally performed by a qualified behavioral health specialist, should assess environmental, familial, and behavioral determinants of obesity as well as suicide risk. Individuals with a history of psychiatric disorders or substance use should be referred for further evaluation by a mental health professional.
• Nutritional assessment and counseling: Evaluation by a registered dietitian is recommended to assess baseline nutritional status and promote pre- and postoperative dietary adherence. Laboratory screening for nutritional deficiencies should include serum iron, vitamin B12, folate, and vitamin D levels.
• Pregnancy and hormonal counseling: Patients of reproductive potential should be advised to avoid conception both before and for 12–18 months following surgery. Contraceptive counseling should include avoidance of estrogen-based methods, as these increase thromboembolic risk and should be discontinued (one menstrual cycle before premenopausal women or 3 weeks for postmenopausal women on hormone replacement therapy). Individuals who conceive after MBS require trimester-specific nutritional evaluation and laboratory monitoring to prevent maternal and fetal deficiencies.
• Tobacco use: Smoking cessation counseling is an essential component of preoperative preparation. Patients are advised to stop smoking as early as possible, ideally 1 year, and at a minimum of 6 weeks, before surgery. Continued tobacco use increases the risk of marginal ulcers (particularly following RYGB), impairs wound healing, and adversely affects postoperative outcomes.
•  Weight reduction before surgery: Although insurance-mandated preoperative weight loss has not been shown to influence surgical outcomes, short-term (2–12 weeks) low-calorie diets may improve hepatic size and glycemic control in patients with type 2 diabetes.
• Additional preoperative testing
• Endoscopic evaluation: Upper endoscopy is recommended for all candidates to detect gastroesophageal reflux disease (GERD), Helicobacter pylori infection, Barrett’s esophagus, hiatal hernia, or esophageal neoplasia, as findings may affect surgical planning.[9]
• Metabolic screening: A fasting lipid profile should be obtained, and dyslipidemia should be managed according to current guidelines.
• Glycemic optimization: Perioperative glucose control should be achieved through comprehensive diabetes management, balancing hemoglobin A1c targets with intraoperative glucose stability.
• Cancer screening: All patients should be up to date with age-appropriate cancer screening as advised by their primary care clinician.

Contraindications

Preoperative candidacy for bariatric surgery should include a careful assessment for conditions that may compromise safety, informed consent, or adherence to long-term postoperative care. Uncontrolled psychosis, severe or untreated major depressive disorder, active eating disorders, ongoing alcohol or drug misuse, prohibitive cardiac disease, severe coagulopathy, and inability to comply with lifelong nutritional supplementation are widely recognized barriers to surgery and should be stabilized or addressed before proceeding.

Clinical Significance

Contemporary Metabolic and Bariatric Surgery Procedures Endorsed by the American Society of Metabolic and Bariatric Surgeons

Roux-en-y gastric bypass

RYGB is traditionally considered the gold standard bariatric operation and is currently the second most frequently performed procedure, accounting for roughly 17% of cases, following sleeve gastrectomy. Originally described by Mason in 1967 as a weight-loss operation, a laparoscopic or robotic approach is primarily used. The operation entails fashioning a small proximal gastric pouch of approximately 15 to 30 mL from the upper stomach, completely separated from the remnant stomach, followed by division of the jejunum 20 to 80 cm distal to the ligament of Treitz. The distal jejunal (Roux limb) limb is anastomosed to the gastric pouch (gastrojejunostomy), and the proximal jejunal segment (biliopancreatic limb, about 50–100 cm) is reconnected to the alimentary limb via a jejunojejunostomy, typically 75 to 150 cm distal to the gastrojejunostomy.[10]

Sleeve gastrectomy

Sleeve gastrectomy is currently the most commonly performed bariatric operation worldwide and represents approximately 60% to 70% of bariatric procedures in the United States. In this procedure, about 70% to 85% of the stomach is resected through a vertical division along the greater curvature using linear staplers guided by a 36 to 40 Fr calibration bougie. Originally conceived as the restrictive component of the duodenal switch, sleeve gastrectomy has evolved into a standalone operation owing to its favorable weight-loss outcomes when performed without the intestinal bypass component. Gastric transection typically begins 4 to 6 cm proximal to the pylorus and extends to the angle of His near the gastroesophageal junction, creating a narrow, tubular gastric conduit along the lesser curvature. Compared with RYGB, sleeve gastrectomy is technically less complex because it avoids small-bowel transection and anastomosis.[11]

Adjustable Gastric Banding

An adjustable silicone band is placed around the upper part of the stomach, immediately below the gastroesophageal junction, creating a gastric pouch of 30 to 40 cc above the band and restricting food intake. The band has a silicone balloon connected to a subcutaneous access port via a tube. Inflating the balloon by injecting saline into the port increases restriction, while deflating it decreases restriction. Once a common procedure, AGB has declined in use due to suboptimal weight loss and higher complication and reoperation rates compared with sleeve gastrectomy and RYGB.

Biliopancreatic Diversion with Duodenal Switch 

The BPD-DS consists of a sleeve gastrectomy, which is the restrictive component of the operation, and a duodenoileostomy. After a sleeve gastrectomy has been performed, the duodenum is divided 2 to 4 cm distal to the pylorus. The ileum is then transected at about 250 to 300 cm from the ileocecal valve. The distal transected small bowel (Roux limb) is connected to the duodenum, while the proximal biliopancreatic limb is anastomosed to the ileum at about 75 to 100 cm from the ileocecal junction. A shorter common channel results in greater weight loss but is more strongly associated with nutritional deficiencies.

Single Anastomosis Duodeno-Ileal Bypass with Sleeve Gastrectomy 

SADI-S is a simplified modification of BPD-DS, where, in addition to sleeve gastrectomy, a single anastomosis is created between the duodenum, as in BPD-DS, and a loop of ileum at about 250 to 300 cm from the ileo-cecal valve. This eliminates the second anastomosis between segments of jejunum as in BPD-DS. This procedure can be performed in a single stage or double stage (sleeve gastrectomy first, followed by duodeno-ileostomy).[12]

One Anastomosis Gastric Bypass 

OAGB, introduced in 1997, is now the third most commonly performed MBS. This involves the creation of a long, narrow gastric conduit and a loop gastrojejunostomy. The gastric pouch is based on the lesser curvature, extending from the angle of His to the Crow’s foot near the incisura angularis of the stomach, calibrated using a 36 to 40 F bougie. The gastric pouch is completely disconnected from the rest of the stomach and connected to the jejunum. The loop of jejunum is connected to the stomach at about 150 to 200 cm from the ligament of Treitz with a gastro-jejunal anastomosis.[13]

Bariatric reoperative procedures

Revisional bariatric procedures constitute approximately 10% to 13% of all bariatric operations. They are generally categorized into 3 groups: (1) conversions, in which 1 bariatric procedure is changed to another (for example, conversion of AGB to sleeve gastrectomy or sleeve gastrectomy to RYGB); (2) corrective operations, performed to optimize the original procedure or manage complications (such as revision of a gastrojejunal anastomotic stricture); and (3) reversals, which restore normal gastrointestinal anatomy.[14]

The leading indications for revisional surgery are weight recurrence or inadequate weight loss (53%) and gastroesophageal reflux disease (32%).[14] In contemporary practice, sleeve gastrectomy has become the index operation most frequently requiring revision, surpassing RYGB. Among sleeve gastrectomy revisions, roughly 80% are converted to RYGB, whereas SADI-S represents about 11%. Revisions are also undertaken after other primary procedures: for AGB, common reasons include port malfunction, band erosion, or weight recurrence; for RYGB, the most frequent indication is a gastrojejunal anastomotic stricture. Many of these interventions are corrective rather than true conversions or reversals, and endoscopic techniques are increasingly utilized where feasible.

Weight-loss outcomes after revisional surgery are modest when compared with primary procedures, with total weight loss at 1 year of about 30% after primary RYGB, 26% following conversion from AGB to RYGB, and 15% after conversion from sleeve gastrectomy to RYGB. These benefits must be balanced against higher morbidity, as revisional surgery is associated with increased 30-day readmission and serious complication rates. However, short-term mortality appears comparable to that of primary bariatric operations. In light of these considerations, revisional bariatric surgery requires judicious patient selection and thorough preoperative counseling, including discussion of conservative strategies and newer anti-obesity pharmacotherapies as part of shared decision-making.[15]

Endoscopic Procedures

Endoscopic bariatric therapies are generally offered to patients with a BMI of 30 kg/m² or higher, or to those with a BMI between 27 and 29.9 kg/m² who also have at least 1 obesity-related comorbidity.[16]

Endoscopic Sleeve Gastroplasty

Endoscopic sleeve gastroplasty is a minimally invasive endoscopic procedure that reduces stomach volume by placing a series of full-thickness sutures along the greater curvature from the prepyloric antrum to the gastroesophageal junction.[17] This reshaping creates a sleeve-like stomach, leading to weight loss through restricted intake, slower gastric emptying, earlier satiety, and favorable hormonal changes, including reductions in ghrelin and improved insulin regulation. Clinical studies have shown that ESG can achieve about 13% total weight loss, compared with minimal weight change with lifestyle intervention alone, accompanied by parallel improvements in obesity-related conditions.[18][18] The procedure has a favorable safety profile, with serious adverse events such as perigastric fluid collections, abscess, or bleeding occurring in roughly 1% to 2% of patients. Although ESG is generally less effective for weight loss than sleeve gastrectomy, it offers the advantages of a lower risk of complications, a shorter procedure duration, and a reduced hospital stay.

Intragastric Balloon

Intragastric balloons promote weight loss by occupying space in the stomach and slowing gastric emptying, thereby enhancing feelings of fullness and reducing food intake. Placement requires upper gastrointestinal endoscopy to position the balloon in the stomach, where it is then filled with saline or air, and subsequent removal is performed endoscopically after approximately 6 to 12 months.[19] Fluid-filled devices generally achieve greater weight loss than air-filled balloons but are associated with a higher rate of gastrointestinal adverse effects.

Newer adjustable balloon systems allow modification of balloon volume over time to balance efficacy and tolerability, with maximal effect typically observed at 6 to 8 months and average total body weight loss of about 10% to 12%. Overall, IGBs are less effective than endoscopic sleeve gastroplasty and are limited by weight regain after device removal, as well as contraindications such as significant hiatal hernia or active gastric ulcer disease. Common adverse effects include abdominal pain, nausea, and vomiting, whereas serious complications such as perforation, bleeding, or bowel obstruction are rare but clinically important.[20]

Investigational Procedures

Currently, the ASMBS does not endorse investigational procedures. These procedures involve aspiration therapy, an endoscopic gastrointestinal bypass device, laparoscopic gastric plication, and bariatric arterial embolization.

Other Issues

Mechanism of Metabolic and Bariatric Surgery 

Earlier descriptions that classified bariatric procedures simply as restrictive or malabsorptive do not fully explain how these operations produce weight loss and metabolic benefits. In addition to mechanical factors, changes in hormones, gut microbiota, metabolism, and neural pathways contribute to postoperative weight reduction and improvements in obesity-related conditions.

Restrictive Mechanism 

Lifestyle modification remains central to perioperative management in bariatric care, but mechanical restriction of stomach volume is an important contributor to weight loss. Among surgical procedures, laparoscopic AGB, sleeve gastrectomy, RYGB, BPD-DS, and SADI-S reduce gastric capacity, thereby limiting caloric intake primarily by restricting intake. Endoscopic therapies, eg, ESG and IGB, similarly promote weight loss by decreasing functional stomach volume and enhancing satiety. While this restrictive mechanism helps initiate early weight reduction, additional hormonal, metabolic, microbial, and neural changes are crucial for sustaining long-term weight loss.

 Malabsorption Mechanism

In procedures, eg, RYGB, BPD-DS, and SADI-S, bypassing the proximal small intestine reduces exposure of ingested nutrients to digestive enzymes and bile, leading to varying degrees of malabsorption of fat, protein, and micronutrients. In RYGB, however, malabsorption contributes only a modest proportion of the reduction in total energy absorption, about 10% to 11%, with other mechanisms playing a larger role in overall weight loss.

Studies show minimal change in carbohydrate and protein absorption after RYGB, whereas fat absorption is measurably reduced, likely related in part to decreased pancreatic exocrine output.[21] Fat malabsorption is most pronounced after BPD-DS, where fecal fat excretion is significantly higher than after RYGB or AGB, and this underlies both the greater weight loss and the higher risk of nutritional deficiencies with this procedure.[22]

Hormonal Mechanism

Glucagon-like peptide-1

Glucagon-like peptide-1 (GLP-1) is responsible for satiety regulation and glucose homeostasis. GLP-1 is secreted by L-cells in the distal ileum and proximal colon in response to food intake. GLP-1 increases beta-cell population and promotes insulin secretion. By its action on central GLP-1 receptors, GLP-1 reduces hepatic glucose production and decreases food intake. The phenomenon of increased insulin secretion in response to oral glucose as compared to intravenous glucose is known as the incretin effect. The incretin effect is mediated by GLP-1 (glucose-dependent insulinotropic polypeptide) and GIP (glucose-dependent insulinotropic polypeptide).

In patients who have type 2 diabetes and obesity, the incretin effect is suppressed, but is restored after sleeve gastrectomy and RYGB. In sleeve gastrectomy, RYGB, BPD-DS, and SADI-S, expedited nutrient delivery to the distal bowel increases L-cell numbers, which secrete GLP-1. GLP-1 levels are consistently elevated following RYGB, but this is not observed in patients who achieve similar weight loss through non-surgical means, suggesting that surgery uniquely modulates GLP-1 levels.[23]

Glucose-dependent insulinotropic polypeptide

Glucose-dependent insulinotropic polypeptide (GIP), previously known as gastric inhibitory peptide, is an incretin, like GLP-1, that regulates postprandial glucose levels. The GIP is secreted by K cells in the duodenum and jejunum in response to food ingestion, predominantly to fat. Circulating GIP levels correlate with BMI and are elevated in obese individuals. GIP induces insulin resistance through its insulinogenic and lipogenic effects, and decreased GIP levels are beneficial for glycemic control. In RYGB and BPD-DS, the entire duodenum and proximal jejunum are bypassed, and K-cells are not exposed to food, potentially leading to reduced GIP secretion.[24]

Peptide YY 

Peptide YY is cosecreted with GLP-1 by the L-cells in the ileum and colon in response to food intake. Peptide YY delays gastric emptying, increases intestinal transit time, and decreases intestinal secretions. The ability of the ileum to delay upper gut motility is referred to as the “ileal brake” and is mediated by peptide YY and GLP-1. In addition, peptide YY induces satiety by its action on appetite centers in the hypothalamus. Peptide YY levels have been found to be elevated after sleeve gastrectomy, RYGB, and BPD-DS. An exaggerated postprandial increase in peptide YY is observed as early as 1 week after gastric bypass, even before any weight loss.[25]

Ghrelin

Ghrelin is secreted by neuroendocrine cells in the oxyntic cells of the gastric fundus. Though described as a “hunger hormone”, ghrelin regulates food intake, adiposity, body weight, and glucose homeostasis by peripheral and central pathways via the vagus nerve. Ghrelin secretion, regulated by the autonomic nervous system, increases preprandially and decreases within the first hour after a meal, more so with carbohydrate than fat intake. Obese individuals have higher ghrelin levels than lean individuals and do not demonstrate decreased levels after food intake. Ghrelin encourages adiposity independent of food intake. This pathway is mediated by IGF-1, which is increased by different neuronal pathways, and can contribute to nonalcoholic fatty liver disease.[26]

Ghrelin levels increase after AGB, similar to changes seen in nonsurgical dietary restriction, which may help explain the short-lived success of this procedure. In sleeve gastrectomy, the gastric fundus, the principal source of ghrelin, is removed, leading to long-term decreases in ghrelin. Studies investigating ghrelin levels following RYGB have demonstrated mixed results. Various studies have reported decreases, no alterations, or increases in fasting and postprandial levels. This variation may be due to heterogeneity in surgical technique during the creation of the gastric pouch and alimentary limb. In BPD-DS, there is a long-term decrease in ghrelin, which contributes to weight loss.[27][28]

Other hormones like glucagon-like peptide-2 (GLP-2), cholecystokinin (CCK), oxyntomodulin, and glicentin play a minor role in weight loss and metabolic effects

Bile Acid Mechanisms 

Bile acids play a role in the absorption of dietary fats and fat-soluble vitamins. Enterohepatic circulation is the pathway through which intestinal bile acids from the liver are reabsorbed in the terminal ileum and move into the portal vein. The excess bile acids that cannot be recycled remain in the peripheral circulation as serum bile acids. A rise in serum total bile acids occurs after all bariatric surgeries except for adjustable gastric banding. This increase in serum bile acids may be secondary to increased hepatic production, increased intestinal reabsorption, or decreased intestinal secretion.

Bile acids exert their metabolic effects through 2 different receptors: 1) A nuclear transcription factor, farnesoid X receptor (FXR), and 2) G-protein-coupled bile acid receptor 1 (TGR5). Bile acids are natural ligands for FXR, and activation of this receptor leads to the production of fibroblast growth factor 19 (FGF19), which plays a role in several favorable metabolic effects, including decreased gluconeogenesis. The TGR5 receptors in L cells of the distal small intestine, when activated by bile acids, produce GLP-1, which helps improve glucose homeostasis. In skeletal muscle and brown adipose tissue, serum bile acids convert tetraiodothyronine (T4) to triiodothyronine (T3) via TGR5 receptor activation, thereby increasing energy expenditure and promoting weight loss.[29]

Gut Microbe Mechanisms 

The gut microbiota ferment carbohydrates and fats, producing short-chain fatty acids (SCFAs). The SCFAs serve as energy sources for the liver, colonic epithelium, and peripheral tissues. The liver uses SCFAs to produce triglycerides that are deposited in adipocytes.21 The SCFAs improve insulin resistance and influence appetite signaling by altering levels of gut hormones like ghrelin, peptide YY, leptin, and GLP-1.

Gut microbes produce secondary bile acids, which stimulate FGF production and improve insulin resistance. Compared with normal-weight individuals, obese patients have relatively low microbial richness and altered composition. Low microbial richness is associated with obesity, insulin resistance, dyslipidemia, and inflammation.[30] There is strong evidence that bariatric surgery induces seemingly favorable changes in the gut microbiota as early as 3 months postoperatively. The effect of a healthier gut microbiome seems to persist over the long term, up to 9 years following bariatric surgery.[31][31]

Postoperative Care Following Metabolic and Bariatric Surgery

Postoperatively, patients typically begin a liquid diet on the day of surgery and receive counseling from a registered dietitian regarding a structured, staged advancement of oral intake over approximately 4 weeks. Lifelong vitamin and mineral supplementation, with periodic laboratory monitoring, is required after all bariatric procedures to prevent and detect nutritional deficiencies. Prolonged (2-4 weeks) venous thromboembolism (VTE) chemoprophylaxis has been associated with a reduction in postoperative thromboembolic events. Conception is generally discouraged for 12 to 18 months following surgery because of rapid weight loss and increased maternal–fetal nutritional demands.

Benefits of Metabolic and Bariatric Surgery

Weight loss outcomes

Metabolic and bariatric surgery provides more robust and durable weight loss than contemporary medical therapy, including GLP-1 receptor agonists. Across procedures, average total weight loss with surgery (see Table. Total Weight Loss With Surgical and Endoscopic Procedures) is approximately 2 to 3 times greater than that achieved with GLP-1RA treatment.[32][33] In a 2-year comparative cohort study, mean total weight loss was about 28% with MBS versus 10% with GLP-1RAs, and this was achieved at lower ongoing treatment costs in the surgical group.[4] 

Body composition changes also differ between modalities: bariatric surgery typically produces a 40% to 50% reduction in fat mass, whereas GLP-1RAs are associated with more modest reductions of 10% to 18% over a similar period.[34] Surgically induced weight loss usually peaks within 1 to 2 years, and although some weight regain is common thereafter, the majority of the initial loss is maintained long term. By contrast, real-world adherence to GLP-1RAs declines substantially over time, with only about 35% to 50% of patients remaining on therapy at 1 year and roughly 15% at 2 years, levels that are substantially lower than those observed in manufacturer-sponsored trials and contribute to attenuated long-term weight-loss outcomes.[35]

 Table. Total Weight Loss With Surgical and Endoscopic Procedures

Table

Type 2 diabetes and glycemic control

Bariatric surgery leads to rapid and substantial improvements in type 2 diabetes, with many patients achieving remission within days of surgery, suggesting that mechanisms beyond weight loss are involved. Proposed contributors include changes in incretin hormones, eg, GLP-1 and GIP, alterations in bile acid signaling, and shifts in the gut microbiome. Favorable predictors of diabetes remission include younger age, shorter disease duration (often less than about 8 years), milder baseline hyperglycemia, and absence of insulin therapy or better preoperative glycemic control.[36] 

Across procedures, average remission rates are approximately 7% to 85% within the first 5 years after surgery, declining to about 18% to 50% beyond 7 years as some patients experience relapse. Among the commonly performed operations, BPD-DS is associated with the highest remission rates and lowest relapse risk, whereas sleeve gastrectomy generally shows the lowest remission rates and a higher likelihood of diabetes recurrence over time.[37]

Cardiovascular benefits

Cardiovascular benefits of MBS include a reduction in heart failure, myocardial failure, stroke, and cardiovascular mortality.[38]

Mortality benefits

Bariatric surgery is associated with a substantial survival advantage, with pooled data demonstrating an approximately 45% to 50% reduction in all-cause mortality and a median increase in life expectancy of about 6 years compared with nonsurgical management. The mortality benefit is particularly pronounced in individuals with pre-existing type 2 diabetes, in whom the relative reduction in death risk and absolute gain in life expectancy are greater than in those without diabetes. These effects are largely driven by marked reductions in deaths related to cardiovascular disease, diabetes, and certain cancers[39]

Cancer reduction

Metabolic and bariatric surgery is associated with an approximate 32% reduction in the incidence of obesity-related cancers and a 48% reduction in cancer-specific mortality compared with nonsurgical management.[40] Weight loss itself appears to be the principal driver of this benefit rather than surgery-specific physiological changes, with a dose–response relationship in which greater postoperative weight reduction correlates with lower cancer risk. Among malignancies, endometrial cancer shows one of the strongest associations with obesity, with risk reductions on the order of 50% to 75% reported following substantial weight loss. Proposed mechanisms include attenuation of chronic systemic inflammation, improvement in hyperinsulinemia and insulin resistance, favorable shifts in sex-steroid hormone and adipokine profiles, and enhancement of immune surveillance

Other benefits

In addition to its effects on weight and metabolic parameters, bariatric surgery is associated with meaningful improvements in health-related quality of life and several obesity-related organ-specific conditions. Clinical studies have shown significant resolution or improvement of obstructive sleep apnea, favorable effects on metabolic dysfunction–associated steatohepatitis, and better renal outcomes, including remission or stabilization of early-stage chronic kidney disease.[41]

Complications of Metabolic and Bariatric Surgery

Perioperative safety of metabolic and bariatric surgery has improved substantially since the early 2000s, with reported mortality rates of approximately 0.08% for primary procedures and up to 0.5% for revisional operations. Short-term serious complications, unplanned reoperations, and readmissions vary by procedure type but generally occur in fewer than 6% of patients.[42] Major perioperative adverse events include staple-line or anastomotic leaks, hemorrhage, bowel obstruction, venous thromboembolism, and the need for reoperation or hospital readmission.

Staple-line leaks

Staple-line leaks after sleeve gastrectomy are relatively uncommon, with reported rates of approximately 0.17% to 0.5%, and their incidence has decreased over time with refinements in surgical technique.[43] Leaks most often arise near the angle of His and are thought to relate to local ischemia from division of the short gastric vessels, elevated intraluminal pressure in very narrow sleeves, and staple length mismatch in areas of greater wall thickness. Affected patients typically present with fever, epigastric pain, tachycardia, and sometimes referred shoulder pain. Recognized risk factors include hypoalbuminemia, active smoking, male sex, higher BMI, type 2 diabetes, immunosuppression, prolonged operative time, and conversion to open surgery. These leaks may require 6 to 8 months or more to fully heal, and management has shifted away from reoperation toward endoscopic strategies that emphasize internal drainage. Due to inflammation and poor tissue quality, endoscopic suturing or clips are frequently unsuccessful, whereas internal drainage using double pigtail stents, endoscopic vacuum therapy, or septotomy has demonstrated higher success rates.[44]

Anastomotic leaks

Anastomotic leaks after RYGB occur in approximately 0.3% to 1.1% of cases, most frequently at the gastrojejunostomy, followed by the gastric pouch, remnant stomach, and jejunojejunostomy.[45] Early leaks, typically occurring within the first 5 postoperative days, are usually related to technical failure, whereas late leaks (beyond 30 days) are more often due to perforated marginal ulcers. Reported risk factors include hypoalbuminemia, active smoking, higher BMI, type 2 diabetes, immunosuppression, and prolonged operative time. Hemodynamically unstable patients diagnosed with leaks require urgent operative intervention, while clinically stable patients with small, contained leaks can often be managed nonoperatively with sepsis control and specialized nutritional support, with success rates approaching 80% in selected series.

Operative management focuses on controlling sepsis with thorough washout and drainage and establishing alternative enteral access; primary repair tends to be more successful for leaks involving the gastric remnant or jejunojejunostomy than for those at the gastrojejunostomy.[46] As with sleeve gastrectomy leaks, selected small leaks in stable patients may also be treated endoscopically using internal drainage with pigtail stents, endoscopic vacuum therapy, or septotomy.

Postoperative hemorrhage 

Postoperative hemorrhage after bariatric surgery occurs in approximately 0.7% to 2.7% of cases, with most events arising within the first 3 postoperative days and roughly 80% resolving without intervention. Preoperative or therapeutic anticoagulation is a major risk factor, and the risk of bleeding is generally higher after RYGB than after sleeve gastrectomy. Tachycardia is the most common presenting sign, often accompanied by abdominal pain. Hemodynamically unstable patients require urgent surgical exploration, whereas stable patients can usually be managed nonoperatively with close monitoring of vital signs, serial hemoglobin measurements, and endoscopic and CT angiographic evaluation, with possible embolization when indicated.[47]

Venous thromboembolism 

Venous thromboembolism occurs in approximately 0.1% to 0.5% of bariatric procedures, with most events arising within the first 3 postoperative months, and pulmonary embolism accounting for nearly one-third of procedure-related deaths. Prior VTE is the strongest individual risk factor. Perioperative chemoprophylaxis is recommended to begin before surgery, and extended post-discharge prophylaxis (2-4 weeks) is advised, as about 80% of VTE events occur after hospital discharge.[8]

Bowel obstruction 

Bowel obstruction is a clinically important complication after bariatric surgery, with reported rates varying by procedure from approximately 0.2% to 4% after sleeve gastrectomy to 6% to 9% after RYGB.[47][48] Early postoperative obstruction is usually related to technical factors, eg, intraluminal clot, kinking, or narrowing at the jejunojejunostomy, whereas late obstruction most often results from internal herniation. Internal hernias arise when small bowel loops protrude through mesenteric defects, typically at the jejunojejunostomy or within Petersen’s space between the transverse colon and the Roux limb mesentery. Routine closure of mesenteric defects with nonabsorbable sutures significantly lowers the risk of internal hernia formation.[49]

Identified risk factors include younger age, greater postoperative weight loss, and pregnancy. Patients often present with vague, crampy abdominal pain, although advanced cases may manifest with severe pain and features of small-bowel obstruction; computed tomography can show a closed-loop pattern, but radiologic signs may be subtle. Given the risk of strangulation and need for bowel resection, even equivocal evidence of a closed-loop obstruction warrants prompt surgical exploration.

Long-term complications 

Long-term complications of metabolic and bariatric surgery include nutritional deficiencies, anastomotic strictures, dumping syndrome, internal hernias, and gallstone disease. Nutritional deficits are the most frequent late complication and occur more often after malabsorptive procedures than after sleeve gastrectomy. Anemia, primarily due to iron and vitamin B12 deficiency, develops in a large proportion of patients, necessitating lifelong vitamin and mineral supplementation with regular laboratory surveillance. Dumping syndrome affects a substantial subset of patients, with up to roughly 40% experiencing postprandial symptoms such as nausea, vomiting, and palpitations within 10 to 30 minutes of eating.

Conclusion

Overall, bariatric surgery is safe and effective in evaluating and treating obese patients, particularly severely obese patients. As discussed above, multiple surgical interventions can provide adequate results. Still, each option has technical and metabolic issues that should be considered when determining which weight-loss surgery is best for each patient. A patient should undergo an extensive preoperative assessment, and a postoperative plan, including a discussion with the interprofessional team, should also be completed. The surgery, along with its associated risks, benefits, and alternatives, should be thoroughly discussed. Given the extent of the risk-to-benefit ratio, which favors surgical intervention in severely obese patients, bariatric surgery can be a viable option for substantial and long-term weight loss as well as comorbidity control.

Enhancing Healthcare Team Outcomes

Obesity is a chronic, progressive, relapsing disease associated with substantial metabolic, cardiovascular, respiratory, and oncologic morbidity, driven by complex interactions among adiposity, neurohormonal signaling, and inflammatory pathways. Clinical evaluation relies on BMI classification, assessment of obesity-related comorbidities, and identification of functional impairment and psychosocial contributors. Management spans lifestyle modification, pharmacotherapy including GLP-1 receptor agonists, and metabolic and bariatric surgery, which remains the most effective and durable intervention for sustained weight loss and comorbidity remission. Appropriate care requires careful patient selection using updated guideline criteria, comprehensive preoperative evaluation, and individualized selection among surgical and endoscopic procedures. Postoperative success depends on structured long-term monitoring for nutritional deficiencies, metabolic complications, and weight recurrence, as well as adherence to lifelong supplementation and behavioral modification.

Interprofessional collaboration is essential to optimize outcomes and safety in bariatric care. Physicians, primary care clinicians, and advanced practitioners coordinate screening, referral, perioperative risk stratification, and long-term disease management. Surgeons provide procedural expertise and complication management, while nurses support perioperative education, monitoring, and early detection of adverse events. Registered dietitians guide pre- and postoperative nutritional optimization and supplementation adherence, and pharmacists assist with medication reconciliation, metabolic management, and nutrient supplementation. Integrated communication and shared decision-making across the team improve patient selection, reduce preventable complications, enhance adherence, and support sustained weight loss and comorbidity control through coordinated, patient-centered care pathways.[50]

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References

1.

Fryar CD, Afful J, Saif NT. NCHS Health E Stats [Internet]. National Center for Health Statistics (US); Hyattsville (MD): Feb, 2026. Prevalence of Overweight, Obesity, and Severe Obesity Among Adults Age 20 and Older: United States, 1960–1962 Through August 2021–August 2023. [PubMed: 41779887]

2.

Nagi MA, Ahmed H, Rezq MAA, Sangroongruangsri S, Chaikledkaew U, Almalki Z, Thavorncharoensap M. Economic costs of obesity: a systematic review. Int J Obes (Lond). 2024 Jan;48(1):33-43. [PubMed: 37884664]

3.

GBD 2021 Adult BMI Collaborators. Global, regional, and national prevalence of adult overweight and obesity, 1990-2021, with forecasts to 2050: a forecasting study for the Global Burden of Disease Study 2021. Lancet. 2025 Mar 08;405(10481):813-838. [PMC free article: PMC11920007] [PubMed: 40049186]

4.

Barrett TS, Hafermann JO, Richards S, LeJeune K, Eid GM. Obesity Treatment With Bariatric Surgery vs GLP-1 Receptor Agonists. JAMA Surg. 2025 Nov 01;160(11):1232-1239. [PMC free article: PMC12444648] [PubMed: 40960852]

5.

Brosnihan P, Luce MS, Yetasook AK, Perez C, Scharf KR, Aly S. Great Debates: Undergoing the Knife versus Pill-Popping-The Comparative Efficacy and Cost-Effectiveness of Bariatric Surgery and GLP-1 Receptor Agonists in the Management of Obesity. Am Surg. 2025 Oct;91(10):1587-1593. [PubMed: 40285863]

6.

Campos GM, Khoraki J, Browning MG, Pessoa BM, Mazzini GS, Wolfe L. Changes in Utilization of Bariatric Surgery in the United States From 1993 to 2016. Ann Surg. 2020 Feb;271(2):201-209. [PubMed: 31425292]

7.

De Luca M, Shikora S, Eisenberg D, Angrisani L, Parmar C, Alqahtani A, Aminian A, Aarts E, Brown WA, Cohen RV, Di Lorenzo N, Faria SL, Goodpaster KPS, Haddad A, Herrera MF, Rosenthal R, Himpens J, Iossa A, Kermansaravi M, Kow L, Kurian M, Chiappetta S, LaMasters T, Mahawar K, Merola G, Nimeri A, O'Kane M, Papasavas PK, Piatto G, Ponce J, Prager G, Pratt JSA, Rogers AM, Salminen P, Steele KE, Suter M, Tolone S, Vitiello A, Zappa M, Kothari SN. Scientific evidence for the updated guidelines on indications for metabolic and bariatric surgery (IFSO/ASMBS). Surg Obes Relat Dis. 2024 Nov;20(11):991-1025. [PubMed: 39419572]

8.

Mechanick JI, Apovian C, Brethauer S, Timothy Garvey W, Joffe AM, Kim J, Kushner RF, Lindquist R, Pessah-Pollack R, Seger J, Urman RD, Adams S, Cleek JB, Correa R, Figaro MK, Flanders K, Grams J, Hurley DL, Kothari S, Seger MV, Still CD. Clinical Practice Guidelines for the Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures - 2019 Update: Cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic and Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists. Obesity (Silver Spring). 2020 Apr;28(4):O1-O58. [PubMed: 32202076]

9.

Campos GM, Mazzini GS, Altieri MS, Docimo S, DeMaria EJ, Rogers AM., Clinical Issues Committee of the American Society for Metabolic and Bariatric Surgery. ASMBS position statement on the rationale for performance of upper gastrointestinal endoscopy before and after metabolic and bariatric surgery. Surg Obes Relat Dis. 2021 May;17(5):837-847. [PubMed: 33875361]

10.

Aleassa EM, Papasavas P, Augustin T, Khorgami Z, Benson-Davies S, Ghiassi S, Carter J, Nimeri A., Clinical Issues Committee of the American Society for Metabolic and Bariatric Surgery. American Society for Metabolic and Bariatric Surgery literature review on the effect of Roux-en-Y gastric bypass limb lengths on outcomes. Surg Obes Relat Dis. 2023 Jul;19(7):755-762. [PubMed: 37268517]

11.

Palermo M, Gagner M. Why We Think Laparoscopic Sleeve Gastrectomy Is a Good Operation: Step-by-Step Technique. J Laparoendosc Adv Surg Tech A. 2020 Jun;30(6):615-618. [PubMed: 32319850]

12.

Sánchez-Pernaute A, Rubio Herrera MA, Pérez-Aguirre E, García Pérez JC, Cabrerizo L, Díez Valladares L, Fernández C, Talavera P, Torres A. Proximal duodenal-ileal end-to-side bypass with sleeve gastrectomy: proposed technique. Obes Surg. 2007 Dec;17(12):1614-8. [PubMed: 18040751]

13.

Carbajo M, García-Caballero M, Toledano M, Osorio D, García-Lanza C, Carmona JA. One-anastomosis gastric bypass by laparoscopy: results of the first 209 patients. Obes Surg. 2005 Mar;15(3):398-404. [PubMed: 15826476]

14.

Vanetta C, Dreifuss NH, Schlottmann F, Baz C, Masrur MA. Bariatric Surgery Conversions in MBSAQIP Centers: Current Indications and Outcomes. Obes Surg. 2022 Oct;32(10):3248-3256. [PubMed: 35918597]

15.

McLennan S, Verhoeff K, Mocanu V, Jogiat U, Birch DW, Karmali S, Switzer NJ. Characteristics and outcomes for patients undergoing revisional bariatric surgery due to persistent obesity: a retrospective cohort study of 10,589 patients. Surg Endosc. 2023 Jun;37(6):4613-4622. [PubMed: 36859722]

16.

Jirapinyo P, Hadefi A, Thompson CC, Patai ÁV, Pannala R, Goelder SK, Kushnir V, Barthet M, Apovian CM, Boskoski I, Chapman CG, Davidson P, Donatelli G, Kumbhari V, Hayee B, Esker J, Hucl T, Pryor AD, Maselli R, Schulman AR, Pattou F, Zelber-Sagi S, Bain PA, Durieux V, Triantafyllou K, Thosani N, Huberty V, Sullivan S. American Society for Gastrointestinal Endoscopy-European Society of Gastrointestinal Endoscopy guideline on primary endoscopic bariatric and metabolic therapies for adults with obesity. Endoscopy. 2024 Jun;56(6):437-456. [PubMed: 38641332]

17.

Abu Dayyeh BK, Edmundowicz S, Thompson CC. Clinical Practice Update: Expert Review on Endoscopic Bariatric Therapies. Gastroenterology. 2017 Mar;152(4):716-729. [PubMed: 28147221]

18.

Abu Dayyeh BK, Bazerbachi F, Vargas EJ, Sharaiha RZ, Thompson CC, Thaemert BC, Teixeira AF, Chapman CG, Kumbhari V, Ujiki MB, Ahrens J, Day C, MERIT Study Group. Galvao Neto M, Zundel N, Wilson EB. Endoscopic sleeve gastroplasty for treatment of class 1 and 2 obesity (MERIT): a prospective, multicentre, randomised trial. Lancet. 2022 Aug 06;400(10350):441-451. [PubMed: 35908555]

19.

Elmaleh-Sachs A, Schwartz JL, Bramante CT, Nicklas JM, Gudzune KA, Jay M. Obesity Management in Adults: A Review. JAMA. 2023 Nov 28;330(20):2000-2015. [PMC free article: PMC11325826] [PubMed: 38015216]

20.

Muniraj T, Day LW, Teigen LM, Ho EY, Sultan S, Davitkov P, Shah R, Murad MH. AGA Clinical Practice Guidelines on Intragastric Balloons in the Management of Obesity. Gastroenterology. 2021 Apr;160(5):1799-1808. [PubMed: 33832655]

21.

Mahawar KK, Sharples AJ. Contribution of Malabsorption to Weight Loss After Roux-en-Y Gastric Bypass: a Systematic Review. Obes Surg. 2017 Aug;27(8):2194-2206. [PubMed: 28585108]

22.

Uribarri-Gonzalez L, Nieto-García L, Martis-Sueiro A, Dominguez-Muñoz JE. Exocrine pancreatic function and dynamic of digestion after restrictive and malabsorptive bariatric surgery: a prospective, cross-sectional, and comparative study. Surg Obes Relat Dis. 2021 Oct;17(10):1766-1772. [PubMed: 34332909]

23.

Hutch CR, Sandoval D. The Role of GLP-1 in the Metabolic Success of Bariatric Surgery. Endocrinology. 2017 Dec 01;158(12):4139-4151. [PMC free article: PMC5711387] [PubMed: 29040429]

24.

Almorza-Gomar D, Díaz-Gómez A, Visiedo F, García-Ortiz JC, Camacho-Ramírez A, Ribelles-García A, Prada-Oliveira JA, Pérez-Arana GM. The role of GIP in carbohydrate metabolism: Implications in the development of therapies for T2DM, a narrative review. Histol Histopathol. 2026 Mar;41(3):371-381. [PubMed: 40755350]

25.

Ballantyne GH. Peptide YY(1-36) and peptide YY(3-36): Part II. Changes after gastrointestinal surgery and bariatric surgery. Obes Surg. 2006 Jun;16(6):795-803. [PubMed: 16756746]

26.

Tuero C, Valenti V, Rotellar F, Landecho MF, Cienfuegos JA, Frühbeck G. Revisiting the Ghrelin Changes Following Bariatric and Metabolic Surgery. Obes Surg. 2020 Jul;30(7):2763-2780. [PubMed: 32323063]

27.

Perakakis N, Kokkinos A, Peradze N, Tentolouris N, Ghaly W, Pilitsi E, Upadhyay J, Alexandrou A, Mantzoros CS. Circulating levels of gastrointestinal hormones in response to the most common types of bariatric surgery and predictive value for weight loss over one year: Evidence from two independent trials. Metabolism. 2019 Dec;101:153997. [PubMed: 31672446]

28.

Slouha E, Elkersh EM, Shay A, Ghosh S, Mahmood A, Gorantla VR. Significance of Hormone Alteration Following Bariatric Surgery. Cureus. 2023 Nov;15(11):e49053. [PMC free article: PMC10729911] [PubMed: 38116338]

29.

Wang W, Cheng Z, Wang Y, Dai Y, Zhang X, Hu S. Role of Bile Acids in Bariatric Surgery. Front Physiol. 2019;10:374. [PMC free article: PMC6454391] [PubMed: 31001146]

30.

Turnbaugh PJ, Ley RE, Hamady M, Fraser-Liggett CM, Knight R, Gordon JI. The human microbiome project. Nature. 2007 Oct 18;449(7164):804-10. [PMC free article: PMC3709439] [PubMed: 17943116]

31.

Lee CJ, Sears CL, Maruthur N. Gut microbiome and its role in obesity and insulin resistance. Ann N Y Acad Sci. 2020 Feb;1461(1):37-52. [PubMed: 31087391]

32.

O'Brien PE, Hindle A, Brennan L, Skinner S, Burton P, Smith A, Crosthwaite G, Brown W. Long-Term Outcomes After Bariatric Surgery: a Systematic Review and Meta-analysis of Weight Loss at 10 or More Years for All Bariatric Procedures and a Single-Centre Review of 20-Year Outcomes After Adjustable Gastric Banding. Obes Surg. 2019 Jan;29(1):3-14. [PMC free article: PMC6320354] [PubMed: 30293134]

33.

ASGE Bariatric Endoscopy Task Force and ASGE Technology Committee. Abu Dayyeh BK, Kumar N, Edmundowicz SA, Jonnalagadda S, Larsen M, Sullivan S, Thompson CC, Banerjee S. ASGE Bariatric Endoscopy Task Force systematic review and meta-analysis assessing the ASGE PIVI thresholds for adopting endoscopic bariatric therapies. Gastrointest Endosc. 2015 Sep;82(3):425-38.e5. [PubMed: 26232362]

34.

Wang Z, Wang L, Zhang X, Lowery BD, Shaffer LL, Chen Y, Wells QS, Flynn CR, Williams B, Spann M, Srivastava G, Samuels JM, Yu D. Body Composition Changes After Bariatric Surgery or Treatment With GLP-1 Receptor Agonists. JAMA Netw Open. 2026 Jan 02;9(1):e2553323. [PMC free article: PMC12789952] [PubMed: 41511769]

35.

Mozaffarian D, Agarwal M, Aggarwal M, Alexander L, Apovian CM, Bindlish S, Bonnet J, Butsch WS, Christensen S, Gianos E, Gulati M, Gupta A, Horn D, Kane RM, Saluja J, Sannidhi D, Stanford FC, Callahan EA. Nutritional priorities to support GLP-1 therapy for obesity: A joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and the Obesity Society. Obes Pillars. 2025 Sep;15:100181. [PMC free article: PMC12264624] [PubMed: 40673264]

36.

American Diabetes Association Professional Practice Committee for Diabetes*. 8. Obesity and Weight Management for the Prevention and Treatment of Diabetes: Standards of Care in Diabetes-2026. Diabetes Care. 2026 Jan 01;49(Suppl 1):S166-S182. [PMC free article: PMC12690172] [PubMed: 41358882]

37.

Celik Esmer A, Sever S, Kundakci B. Comparative Mid- to Long-Term Effects of Bariatric Surgery Versus Medical/Lifestyle Management in Type 2 Diabetes Mellitus: A Network Meta-Analysis of Randomized Controlled Trials. Obes Surg. 2026 Mar;36(3):1304-1314. [PMC free article: PMC13038774] [PubMed: 41572067]

38.

van Veldhuisen SL, Gorter TM, van Woerden G, de Boer RA, Rienstra M, Hazebroek EJ, van Veldhuisen DJ. Bariatric surgery and cardiovascular disease: a systematic review and meta-analysis. Eur Heart J. 2022 May 21;43(20):1955-1969. [PMC free article: PMC9123239] [PubMed: 35243488]

39.

Syn NL, Cummings DE, Wang LZ, Lin DJ, Zhao JJ, Loh M, Koh ZJ, Chew CA, Loo YE, Tai BC, Kim G, So JB, Kaplan LM, Dixon JB, Shabbir A. Association of metabolic-bariatric surgery with long-term survival in adults with and without diabetes: a one-stage meta-analysis of matched cohort and prospective controlled studies with 174 772 participants. Lancet. 2021 May 15;397(10287):1830-1841. [PubMed: 33965067]

40.

Aminian A, Wilson R, Al-Kurd A, Tu C, Milinovich A, Kroh M, Rosenthal RJ, Brethauer SA, Schauer PR, Kattan MW, Brown JC, Berger NA, Abraham J, Nissen SE. Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity. JAMA. 2022 Jun 28;327(24):2423-2433. [PMC free article: PMC9166218] [PubMed: 35657620]

41.

Lingvay I, Sumithran P, Cohen RV, le Roux CW. Obesity management as a primary treatment goal for type 2 diabetes: time to reframe the conversation. Lancet. 2022 Jan 22;399(10322):394-405. [PubMed: 34600604]

42.

Sudan R, Maciejewski ML, Wilk AR, Nguyen NT, Ponce J, Morton JM. Comparative effectiveness of primary bariatric operations in the United States. Surg Obes Relat Dis. 2017 May;13(5):826-834. [PubMed: 28236529]

43.

Osti N, Aboud A, Gumbs S, Sabbagh R, Carryl S, Nazir S, Andrade J, McArthur K. Six-year analysis of 30-day post-operative leaks for primary sleeve gastrectomy: a MBSAQIP database study. Surg Endosc. 2024 Dec;38(12):7451-7458. [PubMed: 39218833]

44.

Kumbhari V, Cummings DE, Kalloo AN, Schauer PR. AGA Clinical Practice Update on Evaluation and Management of Early Complications After Bariatric/Metabolic Surgery: Expert Review. Clin Gastroenterol Hepatol. 2021 Aug;19(8):1531-1537. [PubMed: 33741500]

45.

Vidarsson B, Sundbom M, Edholm D. Incidence and treatment of leak at the gastrojejunostomy in Roux-en-Y gastric bypass: a cohort study of 40,844 patients. Surg Obes Relat Dis. 2019 Jul;15(7):1075-1079. [PubMed: 31201112]

46.

Jacobsen HJ, Nergard BJ, Leifsson BG, Frederiksen SG, Agajahni E, Ekelund M, Hedenbro J, Gislason H. Management of suspected anastomotic leak after bariatric laparoscopic Roux-en-y gastric bypass. Br J Surg. 2014 Mar;101(4):417-23. [PMC free article: PMC4163000] [PubMed: 24536012]

47.

De Simone B, Chouillard E, Ramos AC, Donatelli G, Pintar T, Gupta R, Renzi F, Mahawar K, Madhok B, Maccatrozzo S, Abu-Zidan FM, E Moore E, Weber DG, Coccolini F, Di Saverio S, Kirkpatrick A, Shelat VG, Amico F, Pikoulis E, Ceresoli M, Galante JM, Wani I, De' Angelis N, Hecker A, Sganga G, Tan E, Balogh ZJ, Bala M, Coimbra R, Damaskos D, Ansaloni L, Sartelli M, Pararas N, Kluger Y, Chahine E, Agnoletti V, Fraga G, Biffl WL, Catena F. Operative management of acute abdomen after bariatric surgery in the emergency setting: the OBA guidelines. World J Emerg Surg. 2022 Sep 27;17(1):51. [PMC free article: PMC9516804] [PubMed: 36167572]

48.

Arterburn DE, Telem DA, Kushner RF, Courcoulas AP. Benefits and Risks of Bariatric Surgery in Adults: A Review. JAMA. 2020 Sep 01;324(9):879-887. [PubMed: 32870301]

49.

Stenberg E, Ottosson J, Magnuson A, Szabo E, Wallén S, Näslund E, Thorell A, Näslund I. Long-term Safety and Efficacy of Closure of Mesenteric Defects in Laparoscopic Gastric Bypass Surgery: A Randomized Clinical Trial. JAMA Surg. 2023 Jul 01;158(7):709-717. [PMC free article: PMC10173104] [PubMed: 37163240]

50.

Bullen NL, Parmar J, Gilbert J, Clarke M, Cota A, Finlay IG. How Effective Is the Multidisciplinary Team Approach in Bariatric Surgery? Obes Surg. 2019 Oct;29(10):3232-3238. [PubMed: 31209829]

Disclosure: Umashankkar Kannan declares no relevant financial relationships with ineligible companies.

Disclosure: Amy Sheer declares no relevant financial relationships with ineligible companies.