Bariatric surgery

{{short description|Surgical procedure for management of obesity}} {{Redirect|Obesity surgery|the medical journal|Obesity Surgery}} {{cs1 config|name-list-style=vanc|display-authors=3}} {{Infobox interventions |Name = Bariatric surgery |Image = |Caption = |ICD10 = |ICD9 = |MeshID = D050110 |synonyms = Weight loss surgery }} {{Human body weight}} thumb|381x381px|Diagram showing upper gut before and after stomach bypass surgery. '''Bariatric surgery''' (also known as '''metabolic surgery''' or '''weight loss surgery''') is a group of surgical procedures used to manage obesity and related conditions.<ref name="sand">{{cite journal |vauthors=Sandoval DA, Patti ME |title=Glucose metabolism after bariatric surgery: implications for T2DM remission and hypoglycaemia |journal=Nature Reviews. Endocrinology |volume=19 |issue=3 |pages=164–176 |date=March 2023 |pmid=36289368 |pmc=10805109 |doi=10.1038/s41574-022-00757-5}}</ref><ref name="Rogers-2020">{{cite journal | vauthors = Rogers AM | title = Current State of Bariatric Surgery: Procedures, Data, and Patient Management | journal = Techniques in Vascular and Interventional Radiology | volume = 23 | issue = 1 | article-number = 100654 | date = March 2020 | pmid = 32192634 | doi = 10.1016/j.tvir.2020.100654 | s2cid = 213191179 }}</ref> Long-term weight loss with bariatric surgery may be achieved through alteration of gut hormones, physical reduction of stomach size,<ref name="Cummings_2004">{{cite journal | vauthors = Cummings DE, Overduin J, Foster-Schubert KE | title = Gastric bypass for obesity: mechanisms of weight loss and diabetes resolution | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 89 | issue = 6 | pages = 2608–2615 | date = June 2004 | pmid = 15181031 | doi = 10.1210/jc.2004-0433 }}</ref> reduction of nutrient absorption, or a combination of these.<ref name="Rogers-2020" /><ref name="Pucci-2019" /> Standard of care procedures include Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversion with duodenal switch, from which weight loss is largely achieved by altering gut hormone levels responsible for hunger and satiety, leading to a new hormonal weight set point.<ref name="Pucci-2019">{{cite journal | vauthors = Pucci A, Batterham RL | title = Mechanisms underlying the weight loss effects of RYGB and SG: similar, yet different | journal = Journal of Endocrinological Investigation | volume = 42 | issue = 2 | pages = 117–128 | date = February 2019 | pmid = 29730732 | pmc = 6394763 | doi = 10.1007/s40618-018-0892-2 }}</ref>

In morbidly obese people, bariatric surgery is the most effective treatment for weight loss and reducing complications.<ref>{{cite journal | vauthors = Müller TD, Blüher M, Tschöp MH, DiMarchi RD | title = Anti-obesity drug discovery: advances and challenges | journal = Nature Reviews. Drug Discovery | volume = 21 | issue = 3 | pages = 201–223 | date = March 2022 | pmid = 34815532 | pmc = 8609996 | doi = 10.1038/s41573-021-00337-8 | quote = Bariatric surgery represents the most effective approach to weight loss }}</ref><ref>{{cite journal | vauthors = Bettini S, Belligoli A, Fabris R, Busetto L | title = Diet approach before and after bariatric surgery | journal = Reviews in Endocrine & Metabolic Disorders | volume = 21 | issue = 3 | pages = 297–306 | date = September 2020 | pmid = 32734395 | pmc = 7455579 | doi = 10.1007/s11154-020-09571-8 }}</ref><ref>{{cite journal | vauthors = Zarshenas N, Tapsell LC, Neale EP, Batterham M, Talbot ML | title = The Relationship Between Bariatric Surgery and Diet Quality: a Systematic Review | journal = Obesity Surgery | volume = 30 | issue = 5 | pages = 1768–1792 | date = May 2020 | pmid = 31940138 | doi = 10.1007/s11695-020-04392-9 | quote = Bariatric surgery is currently the most effective treatment for morbid obesity. | s2cid = 210195296 }}</ref><ref>{{cite journal | vauthors = Hedjoudje A, Abu Dayyeh BK, Cheskin LJ, Adam A, Neto MG, Badurdeen D, Morales JG, Sartoretto A, Nava GL, Vargas E, Sui Z, Fayad L, Farha J, Khashab MA, Kalloo AN, Alqahtani AR, Thompson CC, Kumbhari V | title = Efficacy and Safety of Endoscopic Sleeve Gastroplasty: A Systematic Review and Meta-Analysis | journal = Clinical Gastroenterology and Hepatology | volume = 18 | issue = 5 | pages = 1043–1053.e4 | date = May 2020 | pmid = 31442601 | doi = 10.1016/j.cgh.2019.08.022 | s2cid = 201632114 }}</ref><ref>{{cite journal | vauthors = Snoek KM, Steegers-Theunissen RP, Hazebroek EJ, Willemsen SP, Galjaard S, Laven JS, Schoenmakers S | title = The effects of bariatric surgery on periconception maternal health: a systematic review and meta-analysis | journal = Human Reproduction Update | volume = 27 | issue = 6 | pages = 1030–1055 | date = October 2021 | pmid = 34387675 | pmc = 8542997 | doi = 10.1093/humupd/dmab022 | quote = Worldwide, the prevalence of obesity in women of reproductive age is increasing. Bariatric surgery is currently viewed as the most effective, long-term solution for this problem }}</ref> A 2021 meta-analysis found that bariatric surgery was associated with reduction in all-cause mortality among obese adults with or without type 2 diabetes.<ref name=Lancet>{{cite journal | vauthors = 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 | title = 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 | journal = Lancet | volume = 397 | issue = 10287 | pages = 1830–1841 | date = May 2021 | pmid = 33965067 | doi = 10.1016/S0140-6736(21)00591-2 | s2cid = 234345414 }}</ref> This meta-analysis also found that median life-expectancy was 9.3 years longer for obese adults with diabetes who received bariatric surgery as compared to routine (non-surgical) care, whereas the life expectancy gain was 5.1 years for obese adults without diabetes.<ref name=Lancet/> The risk of death in the period following surgery is less than 1 in 1,000.<ref>{{cite journal | vauthors = Robertson AG, Wiggins T, Robertson FP, Huppler L, Doleman B, Harrison EM, Hollyman M, Welbourn R | title = Perioperative mortality in bariatric surgery: meta-analysis | journal = The British Journal of Surgery | volume = 108 | issue = 8 | pages = 892–897 | date = August 2021 | pmid = 34297806 | doi = 10.1093/bjs/znab245 | hdl-access = free | doi-access = free | hdl = 20.500.11820/24849bd8-665f-406f-aac2-b8b1fc0fbb16 }}</ref> Bariatric surgery may also lower disease risk, including improvement in cardiovascular disease risk factors, fatty liver disease, and diabetes management.<ref name="Eisenberg-2022" />

Stomach reduction surgery is frequently used for cases where traditional weight loss approaches, consisting of diet and physical activity, have proven insufficient, or when obesity already significantly affects well-being and general health.<ref name="Cummings_2004" /><ref name="Kaufman_2017">{{cite book | vauthors = Kaufman J, Billing J, Billing P | chapter = Laparoscopic Sleeve Gastrectomy |date=2017 | title = Metabolism and Pathophysiology of Bariatric Surgery |pages=103–112|publisher=Elsevier |language=en |doi=10.1016/b978-0-12-804011-9.00011-x |isbn=978-0-12-804011-9 }}</ref> These procedures involve reducing food intake. Some procedures may also reduce the absorption of carbohydrates, fats, calories, and protein. The outcome is typically a significant reduction in BMI.<ref name="Cummings_2004" /> The efficacy of stomach reduction surgery varies depending on its specific type.<ref name="Kaufman_2017" /> There are two primary divisions: gastric sleeve surgery and gastric bypass surgery. <ref name="Cummings_2004" />

{{as of|2022|10|post=,|lc=n}} the American Society of Metabolic and Bariatric Surgery and the International Federation for the Surgery of Obesity recommended consideration of bariatric surgery for adults meeting two specific criteria: those with a body mass index (BMI) of more than 35 whether or not they have an obesity-associated condition and those with a BMI of 30–35 who have metabolic syndrome.<ref name="Eisenberg-2022" /><ref name="asmbs.org">{{Cite web |date=2022-10-21 |title=After 30 Years — New Guidelines For Weight-Loss Surgery |url=https://asmbs.org/articles/after-30-years-new-guidelines-for-weight-loss-surgery |access-date=2022-11-07 |website=American Society for Metabolic and Bariatric Surgery |language=en-US}}</ref> However, these designated BMI ranges do not hold the same meaning in particular populations, such as among Asians, for whom bariatric surgery may be considered when a BMI is more than 27.5.<ref name="Eisenberg-2022" /> Similarly, the American Academy of Pediatrics recommends bariatric surgery for adolescents 13 and older with a BMI greater than 120% of the 95th percentile for age and sex.<ref>{{Cite journal |url=https://publications.aap.org/pediatrics/article/151/2/e2022060640/190443/Clinical-Practice-Guideline-for-the-Evaluation-and|title=Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity|publisher=American Academy of Pediatrics|volume=151|issue=2|date=February 2023|doi=10.1542/peds.2022-060640 |access-date=July 7, 2023 |journal=Pediatrics |pmid=36622115 | vauthors = Hampl SE, Hassink SG, Skinner AC, Armstrong SC, Barlow SE, Bolling CF, Avila Edwards KC, Eneli I, Hamre R, Joseph MM, Lunsford D, Mendonca E, Michalsky MP, Mirza N, Ochoa ER, Sharifi M, Staiano AE, Weedn AE, Flinn SK, Lindros J, Okechukwu K |article-number=e2022060640 |url-access=subscription}}</ref>

==Medical uses== Bariatric surgery has proven to be the most effective obesity treatment option for enduring weight loss.<ref>{{cite journal | vauthors = Maciejewski ML, Arterburn DE, Van Scoyoc L, Smith VA, Yancy WS, Weidenbacher HJ, Livingston EH, Olsen MK | title = Bariatric Surgery and Long-term Durability of Weight Loss | journal = JAMA Surgery | volume = 151 | issue = 11 | pages = 1046–1055 | date = November 2016 | pmid = 27579793 | pmc = 5112115 | doi = 10.1001/jamasurg.2016.2317 }}</ref> Along with this weight reduction, the procedure reduces risk of cardiovascular diseases, type 2 diabetes, fatty liver disease, depression syndromes, among others.<ref name="ProgCardioDisease">{{cite journal | vauthors = English WJ, Williams DB | title = Metabolic and Bariatric Surgery: An Effective Treatment Option for Obesity and Cardiovascular Disease | journal = Progress in Cardiovascular Diseases | volume = 61 | issue = 2 | pages = 253–269 | date = July 2018 | pmid = 29953878 | doi = 10.1016/j.pcad.2018.06.003 | s2cid = 49592181 }}</ref> While often effective, numerous barriers to shared decision making between the medical provider and person affected include lack of insurance coverage or understanding how it functions, a lack of knowledge about procedures, conflicts with organizational priorities and care coordination, and tools supporting people who need the surgery.<ref>{{cite journal | vauthors = Arterburn D, Tuzzio L, Anau J, Lewis CC, Williams N, Courcoulas A, Stilwell D, Tavakkoli A, Ahmed B, Wilcox M, Fischer GS, Paul K, Handley M, Gupta A, McTigue K | title = Identifying barriers to shared decision-making about bariatric surgery in two large health systems | journal = Obesity | volume = 31 | issue = 2 | pages = 565–573 | date = February 2023 | pmid = 36635226 | doi = 10.1002/oby.23647 | s2cid = 255773525 }}</ref>

=== Eligibility and guidelines === Historically, eligibility for bariatric surgery was defined as a BMI greater than 40, or a BMI more than 35 with an obesity-associated comorbidity, as based on the 1991 NIH Consensus Statement.<ref name="Eisenberg-2022" /> In the three decades that followed, obesity rates continued to rise, laparoscopic surgical techniques made the procedure safer, and high-quality research showed effectiveness at improving health among various conditions.<ref name="asmbs.org" /> In October 2022, ASMBS/IFSO revised the eligibility criteria, which include all adult patients with a BMI greater than 35, and those with a BMI more than 30 with metabolic syndrome.<ref name="asmbs.org" /> However, BMI is a limited measurement, for which factors such as ethnicity are not used in the BMI calculation. Eligibility criteria for bariatric surgery are modified for people who identify as a part of the Asian population with a BMI of more than 27.5.<ref name="Eisenberg-2022" />

Stomach reduction surgeries were highly recommended for patients who meet these criteria: BMI>40 (type 3 obesity), BMI>35 (type 2 obesity), with specific comorbid conditions such as type 2 diabetes, hypertension, dyslipidemia, etc.<ref name="Eisenberg_2022">{{cite journal | vauthors = Eisenberg D, Shikora SA, Aarts E, Aminian A, Angrisani L, Cohen RV, De Luca M, Faria SL, Goodpaster KP, Haddad A, Himpens JM, Kow L, Kurian M, Loi K, Mahawar K, Nimeri A, O'Kane M, Papasavas PK, Ponce J, Pratt JS, Rogers AM, Steele KE, Suter M, Kothari SN | title = 2022 American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO): Indications for Metabolic and Bariatric Surgery | journal = Surgery for Obesity and Related Diseases | volume = 18 | issue = 12 | pages = 1345–1356 | date = December 2022 | pmid = 36280539 | doi = 10.1016/j.soard.2022.08.013 | doi-access = free }}</ref>

{{as of|2019|post=,|lc=n}} the American Academy of Pediatrics recommended bariatric surgery without age-based eligibility limits under the following indications: BMI more than 35 with severe comorbidity, such as obstructive sleep apnea (Apnea-Hypopnea Index above 0.5), type 2 diabetes, idiopathic intracranial hypertension, nonalcoholic steatohepatitis, Blount disease, slipped capital femoral epiphysis, gastroesophageal reflux disease, and idiopathic hypertension or a BMI above 40 without comorbidities.<ref name="aap" /> Surgery is contraindicated with a medically correctable cause of obesity, substance abuse, concurrent or planned pregnancy, eating disorder, or inability to adhere to postoperative recommendations and mandatory lifestyle changes.<ref name="aap">{{cite journal | vauthors = Armstrong SC, Bolling CF, Michalsky MP, Reichard KW | title = Pediatric Metabolic and Bariatric Surgery: Evidence, Barriers, and Best Practices | journal = Pediatrics | volume = 144 | issue = 6 | article-number = e20193223 | date = December 2019 | pmid = 31656225 | doi = 10.1542/peds.2019-3223 | s2cid = 204947687 | doi-access = free }}</ref>

When counseling a patient on bariatric procedures, providers take an interdisciplinary approach. Psychiatric screening is also critical for determining postoperative success.<ref name="Yen-2014" /><ref name="Lin-2013" /> People with a BMI of 40 or greater have a 5-fold risk of depression, and half of bariatric surgery candidates are depressed.<ref name="Yen-2014">{{cite journal | vauthors = Yen YC, Huang CK, Tai CM | title = Psychiatric aspects of bariatric surgery | journal = Current Opinion in Psychiatry | volume = 27 | issue = 5 | pages = 374–379 | date = September 2014 | pmid = 25036421 | pmc = 4162326 | doi = 10.1097/YCO.0000000000000085 }}</ref><ref name="Lin-2013">{{cite journal | vauthors = Lin HY, Huang CK, Tai CM, Lin HY, Kao YH, Tsai CC, Hsuan CF, Lee SL, Chi SC, Yen YC | title = Psychiatric disorders of patients seeking obesity treatment | journal = BMC Psychiatry | volume = 13 | article-number = 1 | date = January 2013 | pmid = 23281653 | pmc = 3543713 | doi = 10.1186/1471-244X-13-1 | doi-access = free }}</ref> Among bariatric surgery candidates and those who undergo bariatric surgery, mental health-related conditions including anxiety disorders, eating disorders, and substance use are also more commonly reported.<ref name="Marchese-2022">{{cite journal | vauthors = Marchese SH, Pandit AU | title = Psychosocial Aspects of Metabolic and Bariatric Surgeries and Endoscopic Therapies | journal = Gastroenterology Clinics of North America | volume = 51 | issue = 4 | pages = 785–798 | date = December 2022 | pmid = 36375996 | doi = 10.1016/j.gtc.2022.07.005 | s2cid = 253486687 }}</ref>

==== Age ==== Elderly patients will face higher postoperative complications due to frailty of elderly patients. The adolescents who performed stomach reduction surgery showed better results and there is no negative impact on linear/puberty growth.<ref name="Eisenberg_2022" />

=== Contraindications === Stomach reduction surgery is not suitable for people with the following conditions: * History of severe gastrointestinal disease: ** Crohn's disease–RYGB surgery limited.<ref name="DuCoin_2020">{{cite book | vauthors = DuCoin C, Moore RL, Provost DA | chapter = Indications and Contraindications for Bariatric Surgery |date=2020 | title = The ASMBS Textbook of Bariatric Surgery |pages=77–81 | veditors = Nguyen NT, Brethauer SA, Morton JM, Ponce J |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-27021-6_6 |isbn=978-3-030-27021-6 }}</ref> ** Active peptic ulcers disease.<ref name="DuCoin_2020" /> ** Esophagitis in severe stage.<ref name="DuCoin_2020" /> * Severe cardiovascular disease ** Heart failure<ref name="DuCoin_2020" /> ** Coronary artery disease<ref name="DuCoin_2020" /> ** Portal hypertension<ref name="DuCoin_2020" /> * Cancer: active cancer diagnosis<ref name="DuCoin_2020" /><ref name="Division of Gastrointestinal Surgery">{{Cite web |title=Contraindications to Weight Loss Surgery |url=https://www.med.unc.edu/surgery/gisurgery/forpatients/diseases-conditions/weightlosssurgery/contraindications-to-weight-loss-surgery/ |access-date=2024-04-10 |website=Division of Gastrointestinal Surgery |language=en-US}}</ref> * Pregnancy: pregnant (within 12-18 month)<ref name="Division of Gastrointestinal Surgery" /> * Psychiatric: lower level of mental capacity or untreated mental disorders<ref name="DuCoin_2020" /><ref name="Division of Gastrointestinal Surgery" /> * Blood clotting: Coagulopathy issue<ref name="Division of Gastrointestinal Surgery" />

===Weight loss=== In adults, malabsorptive procedures lead to more weight loss than restrictive procedures, but they have a higher risk profile.<ref name="Contival-2018" /> Gastric banding is the least invasive, so it may offer fewer complications, while gastric bypass may offer the highest initial and most sustainable weight loss.<ref name="Contival-2018" /> A single protocol is not superior to the other. In one 2019 systematic review, estimated weight loss (EWL) for each surgical protocol is as follows: 56.7% for gastric bypass, 45.9% for gastric banding, 74.1% for biliopancreatic bypass ± duodenal switch and 58.3% for sleeve gastrectomy.<ref>{{cite journal | vauthors = O'Brien PE, Hindle A, Brennan L, Skinner S, Burton P, Smith A, Crosthwaite G, Brown W | title = 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 | journal = Obesity Surgery | volume = 29 | issue = 1 | pages = 3–14 | date = January 2019 | pmid = 30293134 | pmc = 6320354 | doi = 10.1007/s11695-018-3525-0 }}</ref> Most patients do remain obese (BMI 25-35) following surgery despite significant weight loss, and patients with BMI over 40 tended to lose more weight than those with BMI under 40.<ref name="Gloy-2013" /><ref name="Wiggins-2020a" />

Concerning metabolic syndrome, bariatric surgery patients were able to achieve remission 2.4 times as often as those who underwent nonsurgical treatment.<ref name="Wiggins-2020a" /><ref name="Gloy-2013" /> No significant difference was noted for changes in cholesterol, or LDL, but HDL did increase in the surgical groups, and reduction in blood pressure was variable between studies.<ref name="Wiggins-2020a" /><ref name="Gloy-2013" />

=== Type 2 diabetes mellitus === Studies of bariatric surgery for type 2 diabetes (T2DM) within the obese population show that 58% prioritize the improvement of diabetes, while 33% pursued surgery for weight loss alone.<ref name="Zhang-2016">{{cite journal | vauthors = Zhang R, Borisenko O, Telegina I, Hargreaves J, Ahmed AR, Sanchez Santos R, Pring C, Funch-Jensen P, Dillemans B, Hedenbro JL | title = Systematic review of risk prediction models for diabetes after bariatric surgery | journal = The British Journal of Surgery | volume = 103 | issue = 11 | pages = 1420–1427 | date = October 2016 | pmid = 27557164 | doi = 10.1002/bjs.10255 | hdl-access = free | s2cid = 205508036 | hdl = 10044/1/43870 | url = https://lup.lub.lu.se/record/0bca91a9-4038-47c8-b5a4-2087b60ecb80 }}</ref> While weight loss is essential in T2DM management, sustaining improvements long-term is challenging; 50% to 90% of people struggle to achieve adequate diabetes control, suggesting the need for alternative interventions.<ref name="Baskota-2015" /> In this context, studies have reported an 85–90% resolution of T2DM after bariatric surgery, measured by reductions in fasting plasma glucose and HbA1C levels, and remission rates of up to 74% two years post-surgery.<ref name="Baskota-2015">{{cite journal | vauthors = Baskota A, Li S, Dhakal N, Liu G, Tian H | title = Bariatric Surgery for Type 2 Diabetes Mellitus in Patients with BMI <30 kg/m2: A Systematic Review and Meta-Analysis | journal = PLOS ONE | volume = 10 | issue = 7 | article-number = e0132335 | date = 2015-07-13 | pmid = 26167910 | pmc = 4500506 | doi = 10.1371/journal.pone.0132335 | doi-access = free | bibcode = 2015PLoSO..1032335B }}</ref><ref>{{Cite journal |vauthors=Mirghani H, Albalawi I|date=2023-02-24 |title=Metabolic surgery versus usual care effects on diabetes remission: a systematic review and meta-analysis |journal=Diabetology & Metabolic Syndrome |volume=15 |issue=1 |article-number=31 |doi=10.1186/s13098-023-01001-4|doi-access=free |issn=1758-5996 |pmc=9951503 |pmid=36829204}}</ref> Bariatric surgery is considered for individuals with new-onset T2DM and obesity, although the level of improvement may be slightly less.<ref name="Wiggins-2020a" />

The relative risk reductions associated with bariatric surgery are 61%, 64%, and 77% for the development of T2DM, hypertension, and dyslipidemia, respectively, highlighting the efficacy of bariatric surgery in prevention as well as resolution of chronic obesity.<ref name="Wiggins-2020a">{{cite journal | vauthors = Wiggins T, Guidozzi N, Welbourn R, Ahmed AR, Markar SR | title = Association of bariatric surgery with all-cause mortality and incidence of obesity-related disease at a population level: A systematic review and meta-analysis | journal = PLOS Medicine | volume = 17 | issue = 7 | article-number = e1003206 | date = July 2020 | pmid = 32722673 | pmc = 7386646 | doi = 10.1371/journal.pmed.1003206 | doi-access = free }}</ref> Predictors for post-operative diabetes resolution include the current method of diabetes control, adequate blood sugar control, age, duration of diabetes, and waist circumference.<ref name="Zhang-2016" />

Bariatric surgery likewise plays a role in the reduction of medication use.<ref name="Wiggins-2020a" /> During postoperative follow-up, 76% of people discontinued the use of insulin, while 62% no longer required T2DM medications at all.<ref name="Wiggins-2020a" />

===Reduced mortality and morbidity=== A 2021 meta-analysis found that bariatric surgery was associated with 59% and 30% reductions in all-cause mortality among obese adults with or without type 2 diabetes respectively.<ref name="Lancet" /> It also found that median life expectancy was 9 years longer for obese adults with diabetes who received bariatric surgery as compared to routine (non-surgical) care, whereas the life expectancy gain was 5 years longer for obese adults without diabetes.<ref name="Lancet" /> The overall cancer risk in bariatric surgery patients was decreased by 44%, especially in colorectal, endometrial, breast, and ovarian cancer.<ref name="Liao-2022" /> Improvements in cardiovascular health are the most well-described changes after bariatric surgery, with notable reductions in the incidence of stroke (except in patients with T2DM), heart attack, atrial fibrillation, all-cause cardiovascular mortality, and ischemic heart disease.<ref name="Liao-2022" /><ref name="Wiggins-2020a" />

Bariatric surgery in older patients is a safety concern; the relative benefits and risks in this population are not known.<ref name="Cochrane2014">{{cite journal | vauthors = Colquitt JL, Pickett K, Loveman E, Frampton GK | title = Surgery for weight loss in adults | journal = The Cochrane Database of Systematic Reviews | volume = 2014 | issue = 8 | article-number = CD003641 | date = August 2014 | pmid = 25105982 | pmc = 9028049 | doi = 10.1002/14651858.CD003641.pub4 }}</ref>

=== Fertility and pregnancy === In 2017, the American Society for Metabolic and Bariatric Surgery stated that it was not clear whether medical weight-loss treatments or bariatric surgery affected subsequent treatments for infertility in both men and women.<ref>{{cite journal | vauthors = Kominiarek MA, Jungheim ES, Hoeger KM, Rogers AM, Kahan S, Kim JJ | title = American Society for Metabolic and Bariatric Surgery position statement on the impact of obesity and obesity treatment on fertility and fertility therapy - Endorsed by the American College of Obstetricians and Gynecologists and the Obesity Society | journal = Surgery for Obesity and Related Diseases | volume = 13 | issue = 5 | pages = 750–757 | date = May 2017 | pmid = 28416185 | doi = 10.1016/j.soard.2017.02.006 }}</ref>

Bariatric surgery reduces the risk of gestational diabetes and hypertensive disorders of pregnancy in women who later become pregnant, but increases the risks of preterm birth and maternal anemia.<ref name="Liao-2022" /><ref name="Kwong-2018">{{cite journal | vauthors = Kwong W, Tomlinson G, Feig DS | title = Maternal and neonatal outcomes after bariatric surgery; a systematic review and meta-analysis: do the benefits outweigh the risks? | journal = American Journal of Obstetrics and Gynecology | volume = 218 | issue = 6 | pages = 573–580 | date = June 2018 | pmid = 29454871 | doi = 10.1016/j.ajog.2018.02.003 | s2cid = 3837276 }}</ref> A 2021 systematic review found that post-bariatric surgery normalized hormonal levels and menstrual cycles, and improved fertility, with no increased short-term risk of miscarriages or congenital malformations.<ref>{{Cite journal |last1=Snoek |first1=Katinka M |last2=Steegers-Theunissen |first2=Régine P M |last3=Hazebroek |first3=Eric J |last4=Willemsen |first4=Sten P |last5=Galjaard |first5=Sander |last6=Laven |first6=Joop S E |last7=Schoenmakers |first7=Sam |date=2021-12-01 |title=The effects of bariatric surgery on periconception maternal health: a systematic review and meta-analysis |pmc=8542997|pmid=34387675|journal=Human Reproduction Update |volume=27 |issue=6 |pages=1030–1055 |doi=10.1093/humupd/dmab022 |issn=1355-4786}}</ref>

For women with polycystic ovary syndrome, post-operatively there tends to be a reduction in menstrual irregularity, hirsutism, infertility, and the overall prevalence of polycystic ovary syndrome is reduced by bariatric surgery at 12 and 23 months.<ref name="Liao-2022" />

===Mental health=== Among people seeking bariatric surgery, pre-operative mental health disorders are commonly reported.<ref>{{cite journal | vauthors = Morledge MD, Pories WJ | title = Mental Health in Bariatric Surgery: Selection, Access, and Outcomes | journal = Obesity | volume = 28 | issue = 4 | pages = 689–695 | date = April 2020 | pmid = 32202073 | doi = 10.1002/oby.22752 | s2cid = 214618061 }}</ref><ref name="Marchese-2022" /> Some studies indicate that psychological health can improve after bariatric surgery, due in part to improved body image, self-esteem, and change in self-concept; these findings were found in children (see Considerations in adolescent patients below).<ref name="Kubik-2013">{{cite journal | vauthors = Kubik JF, Gill RS, Laffin M, Karmali S | title = The impact of bariatric surgery on psychological health | journal = Journal of Obesity | volume = 2013 | article-number = 837989 | year = 2013 | pmid = 23606952 | pmc = 3625597 | doi = 10.1155/2013/837989 | doi-access = free }}</ref> Bariatric surgery has consistently been associated with postoperative decreases in depression symptoms and reduced severity.<ref name="Kubik-2013" />

==Risks and complications== Weight loss surgery in adults is associated with an elevated risk of complications compared to nonsurgical treatments for obesity.<ref>{{cite journal | vauthors = Beaulac J, Sandre D | title = Critical review of bariatric surgery, medically supervised diets, and behavioural interventions for weight management in adults | journal = Perspectives in Public Health | volume = 137 | issue = 3 | pages = 162–172 | date = May 2017 | pmid = 27354536 | doi = 10.1177/1757913916653425 | s2cid = 3853658 }}</ref><ref>{{cite web |title= Complication | work = NCI's Dictionary of Cancer Terms | publisher = National Cancer Institute, U.S. National Institutes of Health|url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/complication |language=en |date=2 February 2011}}</ref> Complications can be separated into 2 stages, early complication (within 30 days after surgeries) and late complications (after 30 days).<ref name="Woźniewska_2021">{{cite journal | vauthors = Woźniewska P, Diemieszczyk I, Hady HR | title = Complications associated with laparoscopic sleeve gastrectomy - a review | journal = Przeglad Gastroenterologiczny | volume = 16 | issue = 1 | pages = 5–9 | date = 2021 | pmid = 33986881 | pmc = 8112272 | doi = 10.5114/pg.2021.104733 }}</ref>

The overall risk of mortality is low in bariatric surgery at 0 to .01%. Severe complications, such as gastric perforation or necrosis, have been significantly reduced by improved surgical experience and training. Bariatric surgery morbidity is also low at 5%.<ref name="Contival-2018" /><ref name="Wiggins-2020a" /><ref name="Liao-2022" /> In fact, several studies have reported a reduced overall long-term all-cause mortality compared to controls.<ref name="Contival-2018" /><ref name="Wiggins-2020a" /><ref name="Liao-2022" /> However, obese populations maintain an elevated risk of disease and mortality compared to the general population even after surgery, therefore elevated mortality after surgery may be related to the ongoing complications of existing obesity-related disease.<ref name="Contival-2018" /><ref name="Wiggins-2020a" /><ref name="Liao-2022">{{cite journal | vauthors = Liao J, Yin Y, Zhong J, Chen Y, Chen Y, Wen Y, Cai Z | title = Bariatric surgery and health outcomes: An umbrella analysis | journal = Frontiers in Endocrinology | volume = 13 | article-number = 1016613 | date = 2022-10-28 | pmid = 36387921 | pmc = 9650489 | doi = 10.3389/fendo.2022.1016613 | doi-access = free }}</ref>

The percentage of procedures requiring reoperations due to complications was 8% for adjustable gastric banding, 6% after Roux-en-Y gastric bypass, 1% for sleeve gastrectomy, and 5% after biliopancreatic diversion.<ref name="Gloy-2013">{{cite journal | vauthors = Gloy VL, Briel M, Bhatt DL, Kashyap SR, Schauer PR, Mingrone G, Bucher HC, Nordmann AJ | title = Bariatric surgery versus non-surgical treatment for obesity: a systematic review and meta-analysis of randomised controlled trials | journal = BMJ | volume = 347 | article-number = f5934 | date = October 2013 | pmid = 24149519 | pmc = 3806364 | doi = 10.1136/bmj.f5934 }}</ref> Over a 10-year study while using a common data model to allow for comparisons, 9% of patients who received a sleeve gastrectomy required some form of reoperation within 5 years compared to 12% of patients who received a Roux-en-Y gastric bypass. Both of the effects were fewer than those reported with adjustable gastric banding.<ref>{{cite journal | vauthors = Courcoulas A, Coley RY, Clark JM, McBride CL, Cirelli E, McTigue K, Arterburn D, Coleman KJ, Wellman R, Anau J, Toh S, Janning CD, Cook AJ, Williams N, Sturtevant JL, Horgan C, Tavakkoli A | title = Interventions and Operations 5 Years After Bariatric Surgery in a Cohort From the US National Patient-Centered Clinical Research Network Bariatric Study | journal = JAMA Surgery | volume = 155 | issue = 3 | pages = 194–204 | date = March 2020 | pmid = 31940024 | pmc = 6990709 | doi = 10.1001/jamasurg.2019.5470 }}</ref>

=== Postoperative === Laparoscopic bariatric surgery requires an average hospital stay of 2–5 days, barring potential complications.<ref>{{cite journal | vauthors = Małczak P, Pisarska M, Piotr M, Wysocki M, Budzyński A, Pędziwiatr M | title = Enhanced Recovery after Bariatric Surgery: Systematic Review and Meta-Analysis | journal = Obesity Surgery | volume = 27 | issue = 1 | pages = 226–235 | date = January 2017 | pmid = 27817086 | pmc = 5187372 | doi = 10.1007/s11695-016-2438-z }}</ref> Minimally invasive procedures (i.e. adjustable gastric band) tend to have less complications than open procedures (i.e. Roux-en-Y).<ref name="Contival-2018" /><ref name="Liao-2022" /> Similar to other surgical procedures, there is a risk of atelectasis (collapse of small airways) and pleural effusion (fluid buildup in lungs), and pneumonia which tends to be less associated with minimally invasive procedures.<ref name="Contival-2018" /><ref name="Liao-2022" />

Complications specific to the laparoscopic gastric band procedure include esophageal perforation from the advancement of the calibration probe, gastric perforation from the creation of a retrograde gastric tunnel, esophageal dilation, and acute dilation of the gastric pouch due to malpositioning of the gastric band.<ref name="Contival-2018" /> Gastric band malpositioning can be devastating, leading to gastric prolapse, overdistention, and resultingly, gastric ischemia and necrosis.<ref name="Contival-2018">{{cite journal | vauthors = Contival N, Menahem B, Gautier T, Le Roux Y, Alves A | title = Guiding the non-bariatric surgeon through complications of bariatric surgery | journal = Journal of Visceral Surgery | volume = 155 | issue = 1 | pages = 27–40 | date = February 2018 | pmid = 29277390 | doi = 10.1016/j.jviscsurg.2017.10.012 }}</ref> Erosion and migration of the band may also occur post-operatively, in which case, if over 50% of the circumference of the band migrates, then surgical repositioning is necessary.<ref name="Contival-2018" />

Risks of Roux-en-Y gastric bypass include anastomotic stenosis (narrowing of the intestine where the two segments are rejoined), bleeding, leaks, fistula formation, ulcers (ulcers near the rejoined segment), internal hernia, small bowel obstruction, kidney stones, and gallstones.<ref name="Contival-2018" /> Bowel obstruction tends to be more difficult to diagnose in post-bariatric surgery patients due to their reduced ability to vomit; symptoms mainly involve abdominal pain and are intermittent due to twisting and untwisting of the intestinal mesentery.<ref name="Contival-2018" />

Sleeve gastrectomy also carries a small risk of stenosis, staple line leak, stricture formation, leaks, fistula formation, bleeding, and gastro-esophageal reflux disease (also known as GERD or heartburn).<ref name="ProgCardioDisease" /><ref name="Contival-2018" />

Deficiencies of micronutrients like iron (15%), vitamin D, vitamin B12, fat-soluble vitamins, thiamine, and folate are common after bariatric procedures.<ref name="Contival-2018" /><ref name="Gloy-2013" /> Such deficiencies are potentiated by alterations in absorption and lack of appetite and often require supplementation. Notably, chronic vitamin D deficiency may contribute to osteoporosis; insufficiency fractures, especially of the upper extremity, are of higher incidence in bariatric surgery patients.<ref name="Contival-2018" /><ref name="Liao-2022" /> Sleeve gastrectomy leads to fewer long-term vitamin deficiencies compared to gastric banding.

==== Sleeve Gastrectomy (SG) ==== Early complication: Bleeding is present in approximately 5% of cases of sleeve gastrectomy. Symptoms can vary widely, ranging from gastrointestinal bleeding to internal bleeding. Venous thromboembolism (VTE) may occur, causing a decrease in flow through the splenic system, potentially leading to system collapse or death.<ref name="Woźniewska_2021" />

Late complications: They include gastric stenosis, nutrient deficiencies, and Gastroesophageal reflux disease. For gastric stenosis, the symptoms are food intolerance and vomiting.<ref name="Woźniewska_2021" /> For the [https://www.mayoclinic.org/diseases-conditions/gerd/symptoms-causes/syc-20361940 gastroesophageal reflux disease], which due to post-surgery changes of reduced lower esophageal sphincter tension and increased intragastric pressure. Patients may suffer from heartburn after eating or upper abdominal pain.<ref>{{Cite web |title=Gastroesophageal Reflux Disease (GERD) |url=https://www.hopkinsmedicine.org/health/conditions-and-diseases/gastroesophageal-reflux-disease-gerd |access-date=2024-04-10 |website=www.hopkinsmedicine.org |language=en}}</ref>

===== Roux-En-Y Gastric Bypass (RYGB) ===== An early complication of Roux-En-Y Gastric Bypass: Small bowel obstruction, which can be caused by the internal hernias due to the laparoscopic RYGB surgery techniques that were used. And it is life-threatening to patients since it is hard to diagnose through clinical or radiographic imaging.<ref name="Griffith_2012">{{cite journal | vauthors = Griffith PS, Birch DW, Sharma AM, Karmali S | title = Managing complications associated with laparoscopic Roux-en-Y gastric bypass for morbid obesity | journal = Canadian Journal of Surgery | volume = 55 | issue = 5 | pages = 329–336 | date = October 2012 | pmid = 22854113 | pmc = 3468646 | doi = 10.1503/cjs.002011 }}</ref> The symptoms included vomiting, abdominal pain and peritonitis. Common complications such as internal gastrointestinal hemorrhage (bleeding) and staple line leakage occur in both surgeries.<ref name="Griffith_2012" />

Late complication: For the anastomotic stricture,<ref>{{cite journal | vauthors = Kehagias D, Mulita F, Anagnostopoulos F, Kehagias I | title = Management of an early anastomotic stricture using the Seldinger technique | journal = Przeglad Gastroenterologiczny | volume = 17 | issue = 2 | pages = 169–172 | date = 2022 | pmid = 35664021 | pmc = 9165336 | doi = 10.5114/pg.2021.107912 }}</ref> there is a 2.9%-23% chance for patients to experience gastrojejunal anastomosis.<ref name="Griffith_2012" /> This complication more often occurs in the laparoscopic era than open RYGB surgery. Symptoms such as difficulty swallowing and vomiting.<ref name="Griffith_2012" />

=== Gastrointestinal === The most common complication, especially after sleeve gastrectomy, is GERD, which may occur in up to 25% of cases.<ref name="AGEB" /> Dumping syndrome (rapid emptying of undigested stomach contents) is another common complication of bariatric surgery, especially after Roux-en-Y, which is further classified into early and late dumping syndrome.<ref name="AGEB" /> Dumping syndrome in some cases may be associated with more efficient weight loss, however, it can be uncomfortable.<ref name="AGEB" /> Symptoms of dumping syndrome include nausea, diarrhea, painful abdominal cramps, bloating, and autonomic symptoms such as tachycardia, palpitations, flushing, and sweating.<ref name="AGEB" /> Early dumping syndrome (emptying within 1 hour of eating) is also associated with a rapid drop in blood pressure, which may cause fainting.<ref name="AGEB" /> Late dumping syndrome is characterized by low blood sugar 1–3 hours after a meal, presenting with palpitations, tremors, sweating, a feeling of faintness, and irritability.<ref name="AGEB" /> Dumping syndrome is best mitigated by consuming small meals and avoiding high carb or high-fat foods.<ref name="AGEB">{{Cite web |title=AGEB – AGEB Article |url=https://www.ageb.be/ageb-journal/previous-issues/ageb-volume/ageb-type/ageb-article/ |access-date=2023-11-06 |website=AGEB |language=en-GB}}</ref>

===Gallstones=== Rapid weight loss after obesity surgery can contribute to the development of gallstones, especially at 6 and 18 months.<ref name="Contival-2018" /><ref name="Gloy-2013" /> Estimates for prevalence of symptomatic gallstones after Roux-En-Y gastric bypass range from 3–13%.<ref name=ProgCardioDisease/> The risk of gallstones following bariatric surgery has shown to be higher among those of the female sex.<ref>{{cite journal | vauthors = Dai Y, Luo B, Li W | title = Incidence and risk factors for cholelithiasis after bariatric surgery: a systematic review and meta-analysis | journal = Lipids in Health and Disease | volume = 22 | issue = 1 | article-number = 5 | date = January 2023 | pmid = 36641461 | pmc = 9840335 | doi = 10.1186/s12944-023-01774-7 | doi-access = free }}</ref>

=== Kidney stones === Kidney stones are common after Roux-En-Y gastric bypass, with estimates of prevalence ranging from 7-11%.<ref name=ProgCardioDisease/> All surgical modalities are associated with a significant increase in the risk of kidney stones compared to nonsurgical weight loss treatment, with biliopancreatic diversion being the most associated at a ten-fold increase in one study.<ref>{{cite journal | vauthors = Laurenius A, Sundbom M, Ottosson J, Näslund E, Stenberg E | title = Incidence of Kidney Stones After Metabolic and Bariatric Surgery-Data from the Scandinavian Obesity Surgery Registry | journal = Obesity Surgery | volume = 33 | issue = 5 | pages = 1564–1570 | date = May 2023 | pmid = 37000381 | pmc = 10156825 | doi = 10.1007/s11695-023-06561-y }}</ref>

===Micronutrient malnutrition=== Bariatric surgery as a treatment for obesity can lead to vitamin deficiencies. Long-term follow-up reported deficiencies for vitamins D, E, A, K and B12.<ref name=Chen2024>{{cite journal |vauthors=Chen L, Chen Y, Yu X, Liang S, Guan Y, Yang J, Guan B |title=Long-term prevalence of vitamin deficiencies after bariatric surgery: a meta-analysis |journal=Langenbecks Arch Surg |volume=409 |issue=1 |article-number=226 |date=July 2024 |pmid=39030449 |doi=10.1007/s00423-024-03422-9 |url=}}</ref> There are guidelines for multivitamin supplementation, but adherence rates are reported to be less than 20%.<ref name=Ha2021>{{cite journal |vauthors=Ha J, Kwon Y, Kwon JW, Kim D, Park SH, Hwang J, Lee CM, Park S |title=Micronutrient status in bariatric surgery patients receiving postoperative supplementation per guidelines: Insights from a systematic review and meta-analysis of longitudinal studies |journal=Obes Rev |volume=22 |issue=7 |article-number=e13249 |date=July 2021 |pmid=33938111 |doi=10.1111/obr.13249 |url=}}</ref>

=== Bone health === Bariatric surgery has negative effects on bone health, including a decrease in bone density and increased risk of fragility fractures. Suggested mechanisms for this effect include reduced dietary intake of calcium and vitamin d, muscle and skeletal unloading, nutrient malabsorption of and changes in the secretion of gut hormones.<ref>{{Cite journal |last1=Stokar |first1=Joshua |last2=Ben-Porat |first2=Tair |last3=Kaluti |first3=Donia |last4=Abu-Gazala |first4=Mahmud |last5=Weiss |first5=Ram |last6=Mintz |first6=Yoav |last7=Elazari |first7=Ram |last8=Szalat |first8=Auryan |date=2023-08-07 |title=Trabecular Bone Score Preceding and during a 2-Year Follow-Up after Sleeve Gastrectomy: Pitfalls and New Insights |journal=Nutrients |language=en |volume=15 |issue=15 |pages=3481 |doi=10.3390/nu15153481 |pmid=37571418 |pmc=10421136 |doi-access=free |issn=2072-6643 }}</ref> Professional society guidelines recommend assessment of bone density using DXA two years after bariatric surgery.<ref>{{Cite web |title=Bariatric Surgery: Post-Operative Management |url=https://obesitycanada.ca/wp-content/uploads/2025/03/14-Canadian-Adult-Obesity-CPG-Bariatric-Surgery-PostOperativeMgmt.pdf |website=Obesity Canada}}</ref><ref>{{Cite journal |last1=Karam |first1=Léa |last2=Paccou |first2=Julien |date=2025-02-13 |title=Management of Adverse Skeletal Effects Following Bariatric Surgery Procedures in People Living with Obesity |url=https://doi.org/10.1007/s11914-025-00902-9 |journal=Current Osteoporosis Reports |language=en |volume=23 |issue=1 |pages=11 |doi=10.1007/s11914-025-00902-9 |issn=1544-2241 |pmc=11825533 |pmid=39945979}}</ref>

===Pregnancy=== Pregnancy in patients post-bariatric surgery must be carefully monitored. Infant mortality, preterm birth, small fetal size, congenital anomalies, and NICU admission are all elevated in bariatric surgery patients. This elevation in adverse outcomes is thought to be because of malnutrition.<ref name="Akhter-2019" /> Most notably, a reduction in serum folate and iron are well-established correlates to neural tube defects and preterm birth, respectively. People considering pregnancy should consult with their physician before conceiving to optimize their health and nutritional status before pregnancy.<ref name="Akhter-2019">{{cite journal | vauthors = Akhter Z, Rankin J, Ceulemans D, Ngongalah L, Ackroyd R, Devlieger R, Vieira R, Heslehurst N | title = Pregnancy after bariatric surgery and adverse perinatal outcomes: A systematic review and meta-analysis | journal = PLOS Medicine | volume = 16 | issue = 8 | article-number = e1002866 | date = August 2019 | pmid = 31386658 | pmc = 6684044 | doi = 10.1371/journal.pmed.1002866 | doi-access = free }}</ref>

==Technique==

=== Mechanisms of action === Bariatric procedures function by a variety of mechanisms, such as alteration of gut hormones, reduction of the gut size (reducing the amount of food that may pass through), and reduction or blockage of nutrient absorption.<ref name="Rogers-2020" /><ref>{{cite journal | vauthors = Panteliou E, Miras AD | title = What is the role of bariatric surgery in the management of obesity? | journal = Climacteric | volume = 20 | issue = 2 | pages = 97–102 | date = April 2017 | pmid = 28051892 | doi = 10.1080/13697137.2017.1262638 | hdl-access = free | s2cid = 24268282 | hdl = 10044/1/48057 }}</ref> The distinction in these mechanisms, and which are at work for a particular bariatric procedure is not always clearly defined, as multiple mechanisms may be used by a single procedure.<ref name="Rogers-2020" /><ref name="Pucci-2019" /> For instance, while sleeve gastrectomy (discussed below) was initially thought to work simply by reducing the size of the stomach, research has begun to elucidate changes in gut hormone signaling as well.<ref name="ProgCardioDisease" /> The two most frequently performed procedures are sleeve gastrectomy and Roux-en-Y gastric bypass (also called gastric bypass), with sleeve gastrectomy accounting for more than half of all procedures since 2014.<ref name="ProgCardioDisease" />

==== Hormone regulation ==== Studies have shown that bariatric procedures may have additional effects on the hormones that affect hunger and satiety (such as ghrelin and leptin), despite initial development to target reduction of food intake and/or nutrient absorption.<ref name="Rogers-2020" /><ref name="ProgCardioDisease" /><ref name="ReferenceA">{{cite journal | vauthors = Knuth ND, Johannsen DL, Tamboli RA, Marks-Shulman PA, Huizenga R, Chen KY, Abumrad NN, Ravussin E, Hall KD | title = Metabolic adaptation following massive weight loss is related to the degree of energy imbalance and changes in circulating leptin | journal = Obesity | volume = 22 | issue = 12 | pages = 2563–2569 | date = December 2014 | pmid = 25236175 | pmc = 4236233 | doi = 10.1002/oby.20900 }}</ref> This is especially important when considering the durability of weight loss compared to lifestyle changes. While diet and exercise are essential for maintaining a healthy weight and physical fitness, metabolism typically slows as the individual loses weight, a process known as metabolic adaptation.<ref name="ReferenceA" /> Thus, efforts for obese individuals to lose weight often stall, or result in weight re-gain. Bariatric surgery is thought to affect the weight "set point," leading to a more durable weight loss. This is not completely understood but may involve the cell-signaling pathways and hunger/satiety hormones.<ref name="Pucci-2019" />

==== Restricting food intake ==== Procedures may reduce food intake by reducing the size of the stomach that is available to hold a meal (see below: gastric sleeve or stomach folding). Filling the stomach faster enables an individual to feel more full after a smaller meal.<ref name="Rogers-2020" /><ref name="Pucci-2019" /><ref name="Cornejo-Pareja-2019" />

==== Nutrient absorption ==== Procedures may reduce the amount of intestine that food passes through to decrease the absorption of nutrients from food.<ref name="Rogers-2020" /><ref name="Pucci-2019" /> For example, a Roux-en-Y gastric bypass connects the stomach to a more distal part of the intestine, which reduces the ability of the intestines to absorb nutrients from the food.<ref name="Pucci-2019" />

==== Disruption of the gut-brain axis by partial vagotomy ==== Roux-en-Y gastric bypass disrupts the gastric branches of the vagal nerve completely and sleeve gastrectomy does so partially.<ref>{{cite journal | vauthors = Wierdak M, Korbut E, Hubalewska-Mazgaj M, Surmiak M, Magierowska K, Wójcik-Grzybek D, Pędziwiatr M, Brzozowski T, Magierowski M | title = Impact of Vagotomy on Postoperative Weight Loss, Alimentary Intake, and Enterohormone Secretion After Bariatric Surgery in Experimental Translational Models | journal = Obesity Surgery | volume = 32 | issue = 5 | pages = 1586–1600 | date = May 2022 | pmid = 35277793 | doi = 10.1007/s11695-022-05987-0 | url = https://ruj.uj.edu.pl/xmlui/handle/item/290511 }}</ref> Before current bariatriac was introduced, isolated vagotomy was used for the treatment of obesity.<ref>{{cite journal | vauthors = Kral JG | title = Vagotomy for treatment of severe obesity | journal = Lancet | volume = 1 | issue = 8059 | pages = 307–308 | date = February 1978 | pmid = 75340 | doi = 10.1016/S0140-6736(78)90074-0 }}</ref> Vagotomy leads to a reduction of gastric acid and consequently to a reduction in nutrient absorption and a delay in gastric emptying. In addition, the effect of the hunger hormone Ghrelin is reduced, because it acts through the vagal nerve.<ref>{{cite book | vauthors = Date Y | title = Ghrelin | chapter = Ghrelin and the vagus nerve | series = Methods in Enzymology | volume = 514 | pages = 261–269 | date = 2012 | pmid = 22975058 | doi = 10.1016/b978-0-12-381272-8.00016-7 | publisher = Elsevier | isbn = 978-0-12-381272-8 }}</ref> This leads to a reduction of the hunger feeling and weight loss.<ref>{{cite journal | vauthors = Browning KN, Verheijden S, Boeckxstaens GE | title = The Vagus Nerve in Appetite Regulation, Mood, and Intestinal Inflammation | journal = Gastroenterology | volume = 152 | issue = 4 | pages = 730–744 | date = March 2017 | pmid = 27988382 | pmc = 5337130 | doi = 10.1053/j.gastro.2016.10.046 }}</ref>

===Most common techniques=== thumb|Image of sleeve gastrectomy showing the reduced, new stomach (the gastric sleeve) and the removed stomach tissue (resected stomach).

====Sleeve gastrectomy==== thumb|Gastrectomy. {{Main|Sleeve gastrectomy}} Sleeve gastrectomy, also known as a gastric sleeve, is a surgical weight-loss procedure where the stomach size is reduced by the surgical removal of a large portion of the stomach, following along the major curve of the stomach.<ref name="Rogers-2020" /> The open edges are then attached (typically with surgical staples, sutures, or both) to leave the stomach shaped more like a tube, or a sleeve, with a banana shape.<ref name="ProgCardioDisease" />

The procedure is performed laparoscopically and is not reversible. It has been found to produce a weight loss comparable to that of Roux-en-Y gastric bypass.<ref name="ProgCardioDisease" /> The risk of ulcers or narrowing of the gut due to intestinal strictures is less so with sleeve gastrectomy versus Roux-en-Y gastric bypass, but it is not as effective at treating GERD or type 2 diabetes.<ref name="ProgCardioDisease" />

This was the most commonly performed bariatric surgery {{as of|2021|lc=y}} in the United States, and is one of the two most commonly performed bariatric surgeries in the world.<ref name="Rogers-2020" /><ref name="Pucci-2019" /> Though initially thought to work strictly by reducing the size of the stomach, recent research has shown that there are also changes in gut signaling hormones with this procedure leading to weight loss.<ref name="Rogers-2020" /><ref name="Cornejo-Pareja-2019">{{cite journal | vauthors = Cornejo-Pareja I, Clemente-Postigo M, Tinahones FJ | title = Metabolic and Endocrine Consequences of Bariatric Surgery | journal = Frontiers in Endocrinology | volume = 10 | article-number = 626 | date = 2019-09-19 | pmid = 31608009 | pmc = 6761298 | doi = 10.3389/fendo.2019.00626 | doi-access = free }}</ref>

The sleeve gastrectomy mechanism works by creating a narrow gastric lumen which restricts food intake and prevents receptive relaxation, alongside ongoing research into hormonal changes, and gastrointestinal motility.<ref name="Buchwald_2004">{{cite journal | vauthors = Buchwald H, Avidor Y, Braunwald E, Jensen MD, Pories W, Fahrbach K, Schoelles K | title = Bariatric surgery: a systematic review and meta-analysis | journal = JAMA | volume = 292 | issue = 14 | pages = 1724–1737 | date = October 2004 | pmid = 15479938 | doi = 10.1001/jama.292.14.1724 }}</ref><ref name="Ding_2016">{{cite book | vauthors = Ding SA, McKenzie T, Vernon AH, Goldfine AB | chapter = Bariatric Surgery |date=2016 | title = Endocrinology: Adult and Pediatric |pages=479–490.e4 |publisher=Elsevier |language=en |doi=10.1016/b978-0-323-18907-1.00027-5 |isbn=978-0-323-18907-1 }}</ref>

The physical mechanism that will make the SG stand out to other bariatric surgery is its reduction of the storage of the stomach significantly, allowing patients to control their calorie intakes.<ref name="Buchwald_2004" />

The mechanism related to hormone regulation, SG can help to improve Insulin sensitivity, aiming for better glucose regulation and contributing to the remission of type 2 diabetes in many patients. The levels of gut hormones such as GLP-1 and PYY increase after operation of SG.<ref name="Ding_2016" /> GLP-1 enhances insulin secretion and has a satiety-inducing effect, while PYY helps reduce appetite. These hormonal changes are pivotal in the metabolic improvements observed after SG, including better control of blood sugar levels and reduced hunger.<ref name="Buchwald_2004" /><ref name="Huang_2019">{{cite journal | vauthors = Huang R, Ding X, Fu H, Cai Q | title = Potential mechanisms of sleeve gastrectomy for reducing weight and improving metabolism in patients with obesity | journal = Surgery for Obesity and Related Diseases | volume = 15 | issue = 10 | pages = 1861–1871 | date = October 2019 | pmid = 31375442 | doi = 10.1016/j.soard.2019.06.022 | doi-access = free }}</ref>

SG will affect the metabolism and absorption of nutrients, hence causing an effect on nutrient dynamics. Postoperative observation shows patients' nutrient levels of Vitamin B1 and B12 have significantly declined, necessitating careful postoperative nutritional management to prevent deficiencies.<ref name="Buchwald_2004" />

Research suggests SG surgery can alter the composition of the gut microbiota, which plays a role in obesity and metabolic health. Changes in the gut microbial community post-SG may influence energy harvest from the diet, impact inflammatory pathways, and affect the host's metabolic profile.<ref name="Buchwald_2004" />

The key mechanism is gastrointestinal motility adjustment of SG surgery, which impacts the speed and efficiency of food processing.<ref name="Buchwald_2004" /> Studies have observed a modification in the pressure of the lower esophageal sphincter and an increase in intragastric pressure post-surgery, which collectively impact the gastrointestinal motility.<ref name="Buchwald_2004" />

Techniques: * Hiatal Hernia Repair. During SG, identifying and repairing a hiatal hernia (HH) is a significant step that can influence the surgery's outcome, especially concerning gastroesophageal reflux disease (GERD) management postoperatively. The procedure involves dissecting the pars flaccida to open a plane between the right crus of the liver and the esophagus, performing an intrathoracic esophageal dissection, and identifying the left crus.<ref name="Buchwald_2004" /><ref name="Huang_2019" /> A hiatal hernia repair is conducted, if necessary, with a posterior [https://www.clinicasobesitas.com/en/obesity-treatment/cruroplasty/ cruroplasty] using a durable suture material.<ref name="Huang_2019" /> This step is vital as it ensures the proper positioning of the gastroesophageal junction (GEJ) and reduces the risk of postoperative GERD by securing the stomach below the diaphragm, preventing potential acid reflux.<ref name="Huang_2019" /> * Bougie Sizing and Stapling Alongside. The insertion of a bougie during LSG is a crucial technique for guiding the creation of the gastric sleeve. The bougie, which ranges from 38 to 40 French in size, is inserted down to the pylorus under direct visualisation, serving as a mold around which the stomach is stapled and resected.<ref name="Huang_2019" /> This technique ensures that the sleeve is of uniform size and reduces the risk of narrowing a passage or obstruction post-surgery. Stapling begins 3–6&nbsp;cm from the pylorus and proceeds upwards towards the angle of His, closely aligned with the bougie to create a narrow gastric tube.<ref name="Kaufman_2017" /> The careful placement and size of the bougie are instrumental in achieving optimal sleeve shape and function, minimising complications such as leaks or strictures.<ref name="Huang_2019" />

After 1-3 postoperative days, patients begin oral intake, contingent on a successful gastrografin leak test, and receive continuous metabolic monitoring.<ref name="Elrazek_2014" /> To reduce early respiratory risk, prophylactic measures such as oxygen support and ultrasound evaluations are employed.<ref name="Elrazek_2014">{{cite journal | vauthors = Elrazek AE, Elbanna AE, Bilasy SE | title = Medical management of patients after bariatric surgery: Principles and guidelines | journal = World Journal of Gastrointestinal Surgery | volume = 6 | issue = 11 | pages = 220–228 | date = November 2014 | pmid = 25429323 | pmc = 4241489 | doi = 10.4240/wjgs.v6.i11.220 | doi-access = free }}</ref>

Late postoperative care involves careful observation for anastomotic leaks, patient change to a clear liquid diet, and managing potential nausea and vomiting.<ref name="Elrazek_2014" /> After discharge, the focus shifts to dietary management, starting with a full liquid diet and gradually incorporating soft, solid foods. Monitoring includes regular check-ups for weight and blood pressure, along with comprehensive lab tests to ensure optimal recovery.<ref name="Elrazek_2014" />

====Roux-en-Y gastric bypass surgery==== thumb|Image of Roux-en-Y gastric bypass showing the new connection, formed by staples, of the smaller portion of the stomach connected to a further part of the small intestine. thumb|Roux-en-Y gastric bypass. {{main|Gastric bypass surgery}}

Roux-en-Y gastric bypass surgery involves the creation of a new connection in the gastrointestinal tract, from a smaller portion of the stomach to the middle of the small intestine.<ref name="Pucci-2019" />

The surgery is a permanent procedure that aims to decrease the absorption of nutrients due to the new, limited connection created.<ref name="Pucci-2019" /> The surgery also works by affecting gut hormones, resetting hunger and satiety levels.<ref name="Pucci-2019" /> The physically smaller stomach and increase in baseline satiety hormones help people to feel full with less food after the surgery.<ref name="Pucci-2019" />

This is the most commonly performed operation for weight loss in the United States, with approximately 140,000 gastric bypass procedures performed in 2005.<ref name="ProgCardioDisease" /> A 2021 evidence update comparing the benefits and harms of bariatric procedures found that Roux-en-Y gastric bypass surgery and sleeve gastrectomy both effectively reduced weight and led to Type 2 diabetes remission. After five years, Roux-en-Y resulted in greater weight loss (26% compared to 19% for sleeve gastrectomy) and a 25% lower rate of diabetes relapse. However, Roux-en-Y patients had a higher likelihood of hospitalization and additional abdominal surgeries compared to sleeve gastrectomy.<ref>{{Cite web |date=2021-07-15 |title=Comparing the Benefits and Harms of Bariatric Procedures - Evidence Update for Clinicians |url=https://www.pcori.org/evidence-updates/comparing-benefits-and-harms-bariatric-procedures |access-date=2024-10-30 |website=Patient-Centered Outcomes Research Institute (PCORI) |language=en}}</ref> Though, since 2013, sleeve gastrectomy has overtaken RYGB as the most common bariatric procedure.<ref name="ProgCardioDisease" /> RYGB remains one of the two most commonly performed bariatric surgeries in the world.<ref name="Rogers-2020" /><ref name="Pucci-2019" />

Gastric bypass is the most frequently employed technique for weight reduction, the abnormal absorption in the intestines and the physical restriction of the stomach.<ref name="Cummings_2004" /><ref name="Kaufman_2017" /> The types of surgeries can be categorized by the effects and the changes made. Reconstruction of the small intestine to reduce the mucosal area which is used to absorb nutrients is called the Malabsorption operation.<ref name="Kaufman_2017" /> The jejunoileal bypass (JIB) is the most traditional technique for gastric bypass.<ref name="Singh_2009">{{cite journal | vauthors = Singh D, Laya AS, Clarkston WK, Allen MJ | title = Jejunoileal bypass: a surgery of the past and a review of its complications | journal = World Journal of Gastroenterology | volume = 15 | issue = 18 | pages = 2277–2279 | date = May 2009 | pmid = 19437570 | pmc = 2682245 | doi = 10.3748/wjg.15.2277 | doi-access = free }}</ref> This procedure has no limitations in the flow and processing of food;<ref name="Singh_2009" /> it only allows the transport of nutrients from the small intestine to the surrounding areas of the intestine.<ref name="Singh_2009" /> The impact of weight loss is apparent and remarkable.<ref name="Kaufman_2017" /> Individuals who undergo Roux-en-Y gastric bypass (RYGB) consume fewer snacks and meals compared to those who undergo JIB.<ref name="Kaufman_2017" /> The RYGB procedure has been proved to be the most effective medical treatment for type 2 diabetes and weight loss. A decrease in the two hormones related to obesity, leptin and insulin, can be observed after performing gastric bypass surgery.<ref name="Kaufman_2017" />

Roux-en-Y (RYGB) offers two surgical approaches for processing: an open technique or the laparoscopic technique. The majority of cases are still performed with laparoscopy.<ref name="Kaufman_2017" /> The laparoscopic approach is a safe procedure that is associated with fewer problems resulting from wound inflammation.<ref name="Kaufman_2017" />

There are three main areas of techniques for performing laparoscopic RYGB: (1) Anastomotic technique<ref>{{cite web | vauthors = Kate V, Kalayarasan R, Mohta A, Balakrishnan G, Pranavi AR | date = May 2022 | veditors = Roberts KE | title = Intestinal Anastomosis Technique | url = https://emedicine.medscape.com/article/1892319-technique | work = MedScape }}</ref> including Linear Circular stapler. 2) Alimentary limb configuration, such as Antecolic or Retrocolic and Antegastric or Retrogastric. 3) Limb-length of the bilio-pancreatic (BP) limb.<ref name="Kaufman_2017" />

Linear stapling: this technique has two variations. 1) Perform the jejuno-jejunal (JJ) anastomosis, then act on the gastro-jejunal (GJ) anastomosis. 2) reverse the first process.<ref name="Kaufman_2017" />

Jejuno-jejunal first: This technique is prevalent within gastric bypass surgery.

;JJ Anastomosis: In order to facilitate identification of duodenum-jejunum (DJ) flexion and Treitz ligaments, it will act on the Cephalic greater omentum using the laparoscopic staplers and Surgical energy device separate the mesentery.<ref name="Kaufman_2017" /> It also includes measuring the Roux limb between the distal end of the binding and the chosen length. For example, if the weight index is 40, the length should be 100&nbsp;cm.<ref name="Kaufman_2017" /> ;Gastric pouch formation: On the lesser curve of the stomach, a window will be opened between the second and third vessel at the perigastric border. The pouch will be formed using the laparoscopic stapling device. The orogastric tube which will be removed before the first launch of the stapler horizontally.<ref name="Cummings_2004" /><ref name="Kaufman_2017" /> The pouch is produced over the tube with next firings in another direction. These may need the mobilisation to help further divide the stomach.<ref name="Kaufman_2017" /> ;Gastro-jejunal anastomosis: Gastrostomy is created at the specific angle (the part of the pouch with the least blood supply). The separated [https://www.sciencedirect.com/science/article/abs/pii/S1550728921004214 alimentary limbs] are translocated to the pouch antecolically. Enterotomy will processed within the jejunum.<ref name="Cummings_2004" /><ref name="Kaufman_2017" /> At the same time, between the gastric pouch and alimentary limb, the laparoscopic stapling devices create the single firing. According to the JJ anastomosis, the anastomotic defect closes with 2 continuously absorbed sutures. Finally, 50 ml of Dilute methylene blue dye is needed to assess leakage and ensure anastomotic integrity.<ref name="Kaufman_2017" />

Other techniques include the Omega Loop Technique and Trans-abdominal technique employ different operating approaches along with different process orders. All of them will show positive weight loss results.<ref name="Kaufman_2017" />

The duration of the recuperation phase typically ranges from 2 to 4 weeks. The length of the period is dependent upon the self-perception of the patients and their future state of mental and physical ability. For patients to resume their normal activities, a minimum of 3–5 weeks recovery period is required. Doctors should determine the length of the recovery period based on a range of body mass index.<ref name="Woźniewska_2021" />

====Biliopancreatic diversion with duodenal switch==== thumb|upright=1.3|Biliopancreatic diversion The biliopancreatic diversion with duodenal switch (BPD/DS) is a slightly less common bariatric procedure, but is increasing in use with proven efficacy for sustainable weight loss.<ref name="Conner-2023" />

This procedure has multiple steps. First, a sleeve gastrectomy (see above section) is performed. This part of the procedure causes food intake restriction due to the physical reduction of the stomach size, and is permanent.<ref name="Conner-2023" /> Next, the stomach is then disconnected from the upper part of the small intestine and connected to a farther part of the small intestine (ileum), creating the alimentary limb.<ref name="Conner-2023" /> The leftover section of the far part of the small intestine is then used to make a connection that brings digestive fluids from the gallbladder and pancreas to the alimentary limb.<ref name="Conner-2023">{{cite book | vauthors = Conner J, Nottingham JM | chapter = Biliopancreatic Diversion With Duodenal Switch |date=2023 | chapter-url = https://www.ncbi.nlm.nih.gov/books/NBK563193/ | title = StatPearls |access-date=2023-11-08 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=33085340 }}</ref>

Weight loss following the surgery is largely due to the alteration of gut hormones that control hunger and satiety, as well as the physical restriction of the stomach and decrease in nutrient absorption.<ref name="Ding-2020" /> Compared to the sleeve gastrectomy and Roux-en-Y gastric bypass, BPD/DS produces better results with lasting weight loss and resolution of type 2 diabetes.<ref name="Ding-2020">{{cite journal | vauthors = Ding L, Fan Y, Li H, Zhang Y, Qi D, Tang S, Cui J, He Q, Zhuo C, Liu M | title = Comparative effectiveness of bariatric surgeries in patients with obesity and type 2 diabetes mellitus: A network meta-analysis of randomized controlled trials | journal = Obesity Reviews | volume = 21 | issue = 8 | article-number = e13030 | date = August 2020 | pmid = 32286011 | pmc = 7379237 | doi = 10.1111/obr.13030 }}</ref>

=== Other related bariatric procedures === [[File:Blausen 0904 VerticalBandedGastroplasty.png|alt=Vertical Banded Gastroplasty|thumb|Image of a Vertical banded gastroplasty showing staples and a gastric band creating the reduced, new stomach (labeled stomach pouch in the image).<ref name="MIBS2015">{{cite book|veditors = Brethauer SA, Schauer PR, Schirmer BD|title=Minimally Invasive Bariatric Surgery|date=2015-03-03|publisher=Springer|isbn=978-1-4939-1637-5|page=273}}</ref>]]

====Vertical banded gastroplasty==== {{Main|Vertical banded gastroplasty surgery}}

Vertical banded gastroplasty was more commonly used in the 1980s, and is not typically performed in the 21st century.<ref name="Lee-2017">{{cite journal | vauthors = Lee WJ, Almalki O | title = Recent advancements in bariatric/metabolic surgery | journal = Annals of Gastroenterological Surgery | volume = 1 | issue = 3 | pages = 171–179 | date = September 2017 | pmid = 29863165 | pmc = 5881368 | doi = 10.1002/ags3.12030 }}</ref>

In the vertical banded gastroplasty, a part of the stomach is permanently stapled to create a smaller, new stomach.<ref name="Lee-2017" /> This new stomach is physically restricted, allowing people to feel full with smaller meals.<ref name="van Wezenbeek-2015" /> Short-term weight loss is similar to other bariatric procedures, but long-term complications may be higher.<ref name="van Wezenbeek-2015">{{cite journal | vauthors = van Wezenbeek MR, Smulders JF, de Zoete JP, Luyer MD, van Montfort G, Nienhuijs SW | title = Long-Term Results of Primary Vertical Banded Gastroplasty | journal = Obesity Surgery | volume = 25 | issue = 8 | pages = 1425–1430 | date = August 2015 | pmid = 25519773 | doi = 10.1007/s11695-014-1543-0 | s2cid = 23750600 }}</ref>

====Gastric plication==== This procedure is similar to the sleeve gastrectomy surgery, but a sleeve is created by suturing, rather than physically removing stomach tissue.<ref name="Suarez-2021">{{cite journal | vauthors = Suarez DF, Gangemi A | title = How Bad Is "Bad"? A Cost Consideration and Review of Laparoscopic Gastric Plication Versus Laparoscopic Sleeve Gastrectomy | journal = Obesity Surgery | volume = 31 | issue = 1 | pages = 307–316 | date = January 2021 | pmid = 33098054 | doi = 10.1007/s11695-020-05018-w | s2cid = 225049319 }}</ref> This allows for the natural ability of the stomach to absorb nutrients to remain intact.<ref name="Suarez-2021" /> This procedure is reversible, is a less invasive procedure, and does not use hardware or staples.<ref name="Meyer-2021" />

Gastric plication significantly reduces the volume of the patient's stomach, so smaller amounts of food provide a feeling of satiety.<ref name="Meyer-2021" /> In a 2020 review and meta-analysis, long-term weight loss was not as durable as other, more common bariatric techniques.<ref name="Meyer-2021">{{cite journal | vauthors = Meyer HH, Riauka R, Dambrauskas Z, Mickevicius A | title = The effect of surgical gastric plication on obesity and diabetes mellitus type 2: a systematic review and meta-analysis | journal = Wideochirurgia I Inne Techniki Maloinwazyjne = Videosurgery and Other Miniinvasive Techniques | volume = 16 | issue = 1 | pages = 10–18 | date = March 2021 | pmid = 33786112 | pmc = 7991956 | doi = 10.5114/wiitm.2020.97424 }}</ref> Gastric plication has not performed as well as the sleeve gastrectomy, with the sleeve gastrectomy associated with greater weight loss and fewer complications.<ref name="Suarez-2021" />

=== Implants and devices === ==== Adjustable gastric band ==== {{Main|Adjustable gastric band}} thumb|Image of an adjustable gastric band in place over the upper portion of the stomach The restriction of the stomach also can be created using a silicone band, which can be adjusted by the addition or removal of saline through a port placed just under the skin, a procedure called adjustable gastric band surgery.<ref name="Cochrane2014" /> This operation can be performed laparoscopically, and is commonly referred to as a "lap band". Weight loss is predominantly due to the restriction of nutrient intake that is created by the small gastric pouch and the narrow outlet.<ref name="Cochrane2014" /> It is considered somewhat of a safe surgical procedure, with a mortality rate of 0.05%.<ref name="Cochrane2014" />

====Intragastric balloon==== {{main|Intragastric balloon}} Intragastric balloon involves placing a deflated balloon into the stomach, and then filling it to decrease the amount of gastric space, resulting in the feeling of fullness after a smaller meal.<ref name="Fernandes-2007" /><ref name="Singh-2020" /> The balloon can be left in the stomach for a maximum of 6 months and results in weight loss of 3 BMI or 3–8&nbsp;kg within several study ranges.<ref name="Fernandes-2007">{{cite journal | vauthors = Fernandes M, Atallah AN, Soares BG, Humberto S, Guimarães S, Matos D, Monteiro L, Richter B | title = Intragastric balloon for obesity | journal = The Cochrane Database of Systematic Reviews | volume = 2007 | issue = 1 | article-number = CD004931 | date = January 2007 | pmid = 17253531 | pmc = 9022666 | doi = 10.1002/14651858.CD004931.pub2 }}</ref><ref name="Singh-2020">{{cite journal | vauthors = Singh S, de Moura DT, Khan A, Bilal M, Chowdhry M, Ryan MB, Bazarbashi AN, Thompson CC | title = Intragastric Balloon Versus Endoscopic Sleeve Gastroplasty for the Treatment of Obesity: a Systematic Review and Meta-analysis | journal = Obesity Surgery | volume = 30 | issue = 8 | pages = 3010–3029 | date = August 2020 | pmid = 32399847 | pmc = 7720242 | doi = 10.1007/s11695-020-04644-8 }}</ref> Weight loss with the gastric balloon tends to be more modest than other interventions. The intragastric balloon may be used before another bariatric surgery to assist the patient in reaching a weight that is suitable for surgery but can be used repeatedly and unrelated to other procedures.<ref name="Singh-2020" />

====Implantable gastric stimulation==== This procedure where a device similar to a heart pacemaker that is implanted by a surgeon, with the electrical leads stimulating the external surface of the stomach, was under preliminary research in 2015.<ref name="Lal-2015" /> Electrical stimulation is thought to modify the activity of the enteric nervous system of the stomach, which is interpreted by the brain to give a sense of satiety, or fullness. Early evidence suggests that it is less effective than other forms of bariatric surgery.<ref name="Lal-2015">{{cite journal | vauthors = Lal N, Livemore S, Dunne D, Khan I | title = Gastric Electrical Stimulation with the Enterra System: A Systematic Review | journal = Gastroenterology Research and Practice | volume = 2015 | article-number = 762972 | date = 2015 | pmid = 26246804 | pmc = 4515290 | doi = 10.1155/2015/762972 | doi-access = free }}</ref>

==Recovery== People are followed closely both before and after bariatric procedures by a healthcare team. The care team may include people in a variety of disciplines, such as social workers, dietitians, and medical weight management specialists.<ref name="Cochrane2014" /> Follow-up after surgery is typically focused on helping avoid complications and tracking the progress toward body weight goals.<ref name="Cochrane2014" /> Having a structure of social support in the post-operative time may be beneficial as people work through the changes that present physically and emotionally following surgery.<ref name="Marchese-2022" />

=== Dietary recommendations === Dietary restrictions after recovery from surgery depend in part on the type of surgery. In general, immediately after bariatric surgery, the person is restricted to a clear liquid diet, which includes foods such as broth, diluted fruit juices, or sugar-free drinks.<ref name="Elrazek_2014" /> This diet is continued until the gastrointestinal tract begins to recover approximately 2–3 weeks after surgery.<ref name="Elrazek_2014" /> The next stage provides a puréed liquid or soft-solid diet that is slightly increased in viscosity. This may consist of high protein, liquid, or soft foods such as protein shakes, soft meats, and dairy products.<ref name="Cochrane2014" /><ref name="Elrazek_2014" /> People in recovery are encouraged to compose their diet mainly of plant-based foods and soft proteins (1.0–1.5g/kg/day).<ref name="Cochrane2014" /><ref name="Elrazek_2014" /> During recovery, people must adapt to eating more slowly and avoid eating past fullness; overeating may lead to nausea and vomiting.<ref name="Cochrane2014" /><ref name="Elrazek_2014" /> Alcohol is avoided completely in the first 6 months to 1 year after surgery.<ref name="Elrazek_2014" /> Some people may take a daily multivitamin to compensate for reduced absorption of essential nutrients.<ref name="Cochrane2014" />

=== Fertility and family planning === In general, women are advised to avoid pregnancy for 12–24 months after bariatric surgery to reduce the possibility of intrauterine growth restriction or nutrient deficiency, since a person having bariatric surgery will likely undergo significant weight loss and changes in metabolism. Over many years, the rates of potential adverse maternal and fetal outcomes have been reduced for mothers following bariatric surgery.<ref name="Liao-2022" /><ref name="Kwong-2018" /><ref name="Elrazek_2014" />

=== Post-operative bariatric plastic surgery === After a person successfully loses weight following bariatric surgery, excess skin may occur.<ref>{{cite journal | vauthors = Toma T, Harling L, Athanasiou T, Darzi A, Ashrafian H | title = Does Body Contouring After Bariatric Weight Loss Enhance Quality of Life? A Systematic Review of QOL Studies | journal = Obesity Surgery | volume = 28 | issue = 10 | pages = 3333–3341 | date = October 2018 | pmid = 30069862 | pmc = 6153583 | doi = 10.1007/s11695-018-3323-8 }}</ref> Bariatric plastic surgery procedures, sometimes called body contouring, may be an option for people wishing to remove excess skin following the large change in weight.<ref>{{cite journal | vauthors = Cabbabe SW | title = Plastic Surgery after Massive Weight Loss | journal = Missouri Medicine | volume = 113 | issue = 3 | pages = 202–206 | date = 2016 | pmid = 27443046 | pmc = 6140063 }}</ref> Targeted areas include the arms, buttocks and thighs, abdomen, and breasts, with changes occurring slowly over years.<ref>{{cite journal | vauthors = Gilmartin J, Bath-Hextall F, Maclean J, Stanton W, Soldin M | title = Quality of life among adults following bariatric and body contouring surgery: a systematic review | journal = JBI Database of Systematic Reviews and Implementation Reports | volume = 14 | issue = 11 | pages = 240–270 | date = November 2016 | pmid = 27941519 | doi = 10.11124/JBISRIR-2016-003182 | s2cid = 46824125 | url = http://eprints.whiterose.ac.uk/109411/1/JBISRIR-2016-003182Revised.pdf }}</ref>

== Society and culture == The rising prevalence of lawsuits related to gastric bypass surgery is a legal concern in different countries.<ref name="Khan_2016" /> The causes are complex, including the immature characteristics of this technology and an increasing number of patients. In the future, the number of emergent patients who have stomach reduction surgery, long-term complications, and the number of lawsuits due to non-eligible surgery will increase.<ref name="Khan_2016">{{cite book | vauthors = Khan O, Reddy M | chapter = Medico Legal Issues in Bariatric Surgery |date=2016 | title = Obesity, Bariatric and Metabolic Surgery |pages=585–590 | veditors = Agrawal S |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-04343-2_64 |isbn=978-3-319-04342-5 }}</ref>

=== Economic implications === In the 21st century, obesity rates increased globally, and with this, a proportional rise in related diseases and complication.<ref name="ProgCardioDisease" /><ref>{{cite journal | vauthors = Kurz CF, Rehm M, Holle R, Teuner C, Laxy M, Schwarzkopf L | title = The effect of bariatric surgery on health care costs: A synthetic control approach using Bayesian structural time series | journal = Health Economics | volume = 28 | issue = 11 | pages = 1293–1307 | date = November 2019 | pmid = 31489749 | doi = 10.1002/hec.3941 | s2cid = 201845178 | hdl = 10419/230048 | hdl-access = free }}</ref> In the United States during 2017-20, an estimated 40% of adults were obese, up from 30% in 1999-2000.<ref name="ProgCardioDisease" /> The costs of treating obesity and related conditions has a large economic impact globally.<ref>{{cite journal | vauthors = Tremmel M, Gerdtham UG, Nilsson PM, Saha S | title = Economic Burden of Obesity: A Systematic Literature Review | journal = International Journal of Environmental Research and Public Health | volume = 14 | issue = 4 | page = 435 | date = April 2017 | pmid = 28422077 | pmc = 5409636 | doi = 10.3390/ijerph14040435 | doi-access = free }}</ref><ref name="Liu-2021">{{cite journal | vauthors = Liu D, Cheng Q, Suh HR, Magdy M, Loi K | title = Role of bariatric surgery in a COVID-19 era: a review of economic costs | journal = Surgery for Obesity and Related Diseases | volume = 17 | issue = 12 | pages = 2091–2096 | date = December 2021 | pmid = 34417118 | pmc = 8310782 | doi = 10.1016/j.soard.2021.07.015 }}</ref> This economic impact results from direct treatment of obesity, treatment of obesity-related conditions, as well as other economic losses from decreased workforce productivity.<ref name="ProgCardioDisease" /><ref name="Liu-2021" />

Bariatric surgery is cost-effective when compared to savings estimated from treatment or prevention of obesity-related conditions.<ref name="Liu-2021" /> Cost-effectiveness occurs at the individual level due to fewer healthcare expenses for medications, and nationally with a reduction in the overall lifetime healthcare costs.<ref>{{cite journal | vauthors = Larsen AT, Højgaard B, Ibsen R, Kjellberg J | title = The Socio-economic Impact of Bariatric Surgery | journal = Obesity Surgery | volume = 28 | issue = 2 | pages = 338–348 | date = February 2018 | pmid = 28735376 | doi = 10.1007/s11695-017-2834-z | s2cid = 2381246 }}</ref><ref name="Liu-2021" />

==Special populations==

===Adolescents=== {{See also|Informed consent#Children}} During the early 21st century, obesity among children and adolescents increased globally, as did treatment options including lifestyle changes, drug treatments, and surgical procedures.<ref name="Hofmann">{{cite journal | vauthors = Hofmann B | title = Bariatric surgery for obese children and adolescents: a review of the moral challenges | journal = BMC Medical Ethics | volume = 14 | issue = 1 | article-number = 18 | date = April 2013 | pmid = 23631445 | pmc = 3655839 | doi = 10.1186/1472-6939-14-18 | doi-access = free }}</ref><ref name="Jebeile-2022">{{cite journal | vauthors = Jebeile H, Kelly AS, O'Malley G, Baur LA | title = Obesity in children and adolescents: epidemiology, causes, assessment, and management | journal = The Lancet. Diabetes & Endocrinology | volume = 10 | issue = 5 | pages = 351–365 | date = May 2022 | pmid = 35248172 | pmc = 9831747 | doi = 10.1016/S2213-8587(22)00047-X }}</ref> The medical complications and health concerns associated with childhood obesity may have short or long-term effects, with a growing concern of a potential decline in overall life expectancy.<ref name="Jebeile-2022" /><ref name="aap" /> Childhood obesity may affect mental health and impact eating practices.<ref name="Jebeile-2022" />

Difficulties surrounding obesity treatment selection among children and adolescents include ethical considerations when obtaining consent from those who may be unable to do so without adult guidance or understanding the potential lasting effects of invasive procedures.<ref name="Hofmann" /><ref>{{cite journal | vauthors = Martinelli V, Singh S, Politi P, Caccialanza R, Peri A, Pietrabissa A, Chiappedi M | title = Ethics of Bariatric Surgery in Adolescence and Its Implications for Clinical Practice | journal = International Journal of Environmental Research and Public Health | volume = 20 | issue = 2 | page = 1232 | date = January 2023 | pmid = 36673981 | pmc = 9859476 | doi = 10.3390/ijerph20021232 | doi-access = free }}</ref> Among high-quality randomized control trial data for surgical treatment of obesity, many studies are not specific to children and adolescents.<ref>{{cite journal | vauthors = Torbahn G, Brauchmann J, Axon E, Clare K, Metzendorf MI, Wiegand S, Pratt JS, Ells LJ | title = Surgery for the treatment of obesity in children and adolescents | journal = The Cochrane Database of Systematic Reviews | volume = 2022 | issue = 9 | article-number = CD011740 | date = September 2022 | pmid = 36074911 | pmc = 9454261 | doi = 10.1002/14651858.CD011740.pub2 }}</ref> Concerns for bullying about overweight or body image exist for those with childhood obesity; self-harm among children and adolescents bullied for their weight also occurs.<ref name="Jebeile-2022" />

Bariatric surgical procedures available to adolescents include: Roux-en-Y gastric bypass, vertical sleeve gastrectomy, and adjustable gastric banding.<ref>{{cite journal | vauthors = Thenappan A, Nadler E | title = Bariatric Surgery in Children: Indications, Types, and Outcomes | journal = Current Gastroenterology Reports | volume = 21 | issue = 6 | article-number = 24 | date = April 2019 | pmid = 31025124 | doi = 10.1007/s11894-019-0691-8 | s2cid = 133605416 }}</ref> Multiple organizations have created guidelines for bariatric surgery indications in children and adolescents. In 2022-23, such guidelines overlapped with recommendations for potential bariatric surgical management in children and adolescents with a BMI of 40 or higher, or a BMI of 35 or higher while also experiencing related experiences.<ref>{{cite journal | vauthors = Elkhoury D, Elkhoury C, Gorantla VR | title = Improving Access to Child and Adolescent Weight Loss Surgery: A Review of Updated National and International Practice Guidelines | journal = Cureus | volume = 15 | issue = 4 | article-number = e38117 | date = April 2023 | pmid = 37252536 | pmc = 10212726 | doi = 10.7759/cureus.38117 | doi-access = free }}</ref><ref name="Eisenberg-2022">{{cite journal | vauthors = Eisenberg D, Shikora SA, Aarts E, Aminian A, Angrisani L, Cohen RV, De Luca M, Faria SL, Goodpaster KP, Haddad A, Himpens JM, Kow L, Kurian M, Loi K, Mahawar K, Nimeri A, O'Kane M, Papasavas PK, Ponce J, Pratt JS, Rogers AM, Steele KE, Suter M, Kothari SN | title = 2022 American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO): Indications for Metabolic and Bariatric Surgery | journal = Surgery for Obesity and Related Diseases | volume = 18 | issue = 12 | pages = 1345–1356 | date = December 2022 | pmid = 36280539 | doi = 10.1016/j.soard.2022.08.013 | s2cid = 253077054 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Hampl SE, Hassink SG, Skinner AC, Armstrong SC, Barlow SE, Bolling CF, Avila Edwards KC, Eneli I, Hamre R, Joseph MM, Lunsford D, Mendonca E, Michalsky MP, Mirza N, Ochoa ER, Sharifi M, Staiano AE, Weedn AE, Flinn SK, Lindros J, Okechukwu K | title = Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity | journal = Pediatrics | volume = 151 | issue = 2 | article-number = e2022060640 | date = February 2023 | pmid = 36622115 | doi = 10.1542/peds.2022-060640 | s2cid = 255544218 }}</ref>

Reviews have shown similar weight loss in adolescents following bariatric surgery as in adults.<ref name="Beamish-2023">{{cite journal | vauthors = Beamish AJ, Ryan Harper E, Järvholm K, Janson A, Olbers T | title = Long-term Outcomes Following Adolescent Metabolic and Bariatric Surgery | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 108 | issue = 9 | pages = 2184–2192 | date = August 2023 | pmid = 36947630 | pmc = 10438888 | doi = 10.1210/clinem/dgad155 }}</ref> Reduction of eating disorders for several years after bariatric surgery has also been shown in adolescents after bariatric surgery.<ref name="Beamish-2023" /> Long-term reduction in or resolution of weight-related conditions, such as diabetes and high blood pressure, occurred in adolescents after bariatric surgery.<ref name="Wu-2023">{{cite journal | vauthors = Wu Z, Gao Z, Qiao Y, Chen F, Guan B, Wu L, Cheng L, Huang S, Yang J | title = Long-Term Results of Bariatric Surgery in Adolescents with at Least 5 Years of Follow-up: a Systematic Review and Meta-Analysis | journal = Obesity Surgery | volume = 33 | issue = 6 | pages = 1730–1745 | date = June 2023 | pmid = 37115416 | doi = 10.1007/s11695-023-06593-4 | s2cid = 258375355 }}</ref> Long-term effects of bariatric surgery in adolescents remains under research, as of 2023.<ref name="Beamish-2023" /><ref name="Wu-2023" />

== History == Techniques for weight loss have been reported for decades, with a more formal transition to noting weight loss following surgical intervention in the 1950s when subsequent weight loss after surgical shortening of the small intestine in dogs and people was observed.<ref name="Moshiri-2013">{{cite journal | vauthors = Moshiri M, Osman S, Robinson TJ, Khandelwal S, Bhargava P, Rohrmann CA | title = Evolution of bariatric surgery: a historical perspective | journal = AJR. American Journal of Roentgenology | volume = 201 | issue = 1 | pages = W40–W48 | date = July 2013 | pmid = 23789695 | doi = 10.2214/AJR.12.10131 }}</ref><ref name="Faria-2017">{{cite journal | vauthors = Faria GR | title = A brief history of bariatric surgery | journal = Porto Biomedical Journal | volume = 2 | issue = 3 | pages = 90–92 | date = 2017 | pmid = 32258594 | pmc = 6806981 | doi = 10.1016/j.pbj.2017.01.008 }}</ref> Specifically, anastomosis between upper and lower portions of the small intestine to skip, or bypass, part of the small intestine led to what was called the jejuno-ileal bypass.<ref name="Faria-2017" /> A modified version of this procedure showed long-term improvement of lipid levels in people with known high levels of cholesterol following the procedure.<ref name="Faria-2017" />

Further modification of the bypass procedure achieved weight loss in obesity, during which an anastomosis between the small intestine and upper lower intestine, known as a jejunocolic bypass, was performed.<ref name="Moshiri-2013" /> During the late 1960s, the initiation of bariatric surgery followed the development of a procedure to bypass portions of the stomach – the gastric bypass.<ref name="Moshiri-2013" /><ref name="Faria-2017" /><ref name="Faria_2017">{{cite journal | vauthors = Faria GR | title = A brief history of bariatric surgery | journal = Porto Biomedical Journal | volume = 2 | issue = 3 | pages = 90–92 | date = 2017-03-06 | pmid = 32258594 | pmc = 6806981 | doi = 10.1016/j.pbj.2017.01.008 }}</ref>

Sleeve gastrectomy (SG), is one of the most popular stomach reduction surgeries and was earliest performed in 1990 as a first-stage operation of duodenal switch (DS) surgery. Patients who go through SG typically experience substantial weight loss, preventing the need for the second phase of DS.<ref name="Faria_2017" />

Laparoscopic techniques revolutionized bariatric surgery, making procedures less invasive and recovery quicker. The first laparoscopic gastric bypass performed by Alan Wittgrove in 1994 exemplifies this leap in surgical innovation.<ref name="Faria_2017" /> The SG laparoscopic version was first performed in 1999.<ref name="Kaufman_2017" />

Historically, the RYGBP is the best bariatric surgery for obese patients, but now being rivalled by the SG. The complication of RYGBP leads people to find less intricate and safer surgeries, the complication including internal hernias and anastomotic complications.<ref name="Kaufman_2017" /> Nowadays, SG has a lower risk of complication, and the mortality rate has become the more favorable option for the patients.<ref name="Lee-2017" />

== See also == * Revision weight loss surgery * Endoscopic sleeve gastroplasty

== References == {{Reflist}}

== External links == * {{Commons category-inline}} {{Obesity|state=expanded}} {{Digestive system procedures}}

{{DEFAULTSORT:Bariatric surgery}} Surgery Category:Surgical specialties