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Bariatric Surgery · the truth
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In one pass For true severe obesity, bariatric surgery produces the largest and longest-lasting weight loss of any current option, and in long-term controlled studies the people who had it also had lower mortality.
Educational content, not medical advice — consult a clinician.
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Chapter 1
Types of weight-loss surgery
For true severe obesity, bariatric surgery produces the largest and longest-lasting weight loss of any current option, and in long-term controlled studies the people who had it also had lower mortality. But its costs are real; it is not a shortcut for the lazy.
It changes the structure of the digestive tract: the stomach is made smaller, and some operations also route food past a stretch of small intestine. Once that is done, the hunger and fullness signals sent by the gut change as well, so it has long been more than making the stomach smaller. The more accurate modern name is metabolic surgery.
For people who truly qualify, the risk of the operation is now lower than the risk of leaving severe obesity untreated, so international guidelines hold that for suitable patients, earlier usually brings more benefit than later. Since 2022, surgery has been recommended at a body mass index () of 35 or more, with or without complications; the threshold is lower for Asian patients, and China's guideline uses BMI ≥ 32.5, or ≥ 27.5 with type 2 diabetes.
If you have had the operation and then develop fever, a racing heart, or abdominal pain that keeps getting worse, or become confused or unsteady on your feet after severe vomiting, get medical care immediately.
It changes the structure of the digestive tract: the stomach is made smaller, and some operations also route food past a stretch of small intestine. Once that is done, the hunger and fullness signals sent by the gut change as well, so it has long been more than making the stomach smaller. The more accurate modern name is metabolic surgery.
For people who truly qualify, the risk of the operation is now lower than the risk of leaving severe obesity untreated, so international guidelines hold that for suitable patients, earlier usually brings more benefit than later. Since 2022, surgery has been recommended at a body mass index () of 35 or more, with or without complications; the threshold is lower for Asian patients, and China's guideline uses BMI ≥ 32.5, or ≥ 27.5 with type 2 diabetes.
If you have had the operation and then develop fever, a racing heart, or abdominal pain that keeps getting worse, or become confused or unsteady on your feet after severe vomiting, get medical care immediately.
Clinical · The operations and who qualifies
Two mainstream operations account for almost all current practice:Sleeve gastrectomy (SG): about 80% of the stomach is cut away lengthwise along its greater curvature, leaving a narrow sleeve; the route through the intestine is unchanged. It is the simplest and quickest to perform and has fewer nutritional complications than gastric bypass, and since 2013 it has been the most-performed operation worldwide.Roux-en-Y gastric bypass (RYGB): the stomach is made into a pouch of about 30 mL, and food bypasses most of the remaining stomach and a length of small intestine. Historically it was the gold standard, with the most durable weight loss and the highest diabetes remission rate.
A few other operations are used rarely. The adjustable gastric band (Lap-Band) of earlier years is now seldom placed. Biliopancreatic diversion procedures (BPD/DS, SADI-S) take off the most weight but carry heavy nutritional complications, and are done only for extreme obesity at specialist centers.
The indications widened sharply in 2022 (Eisenberg 2022, the joint ASMBS/IFSO statement, which replaced the 1991 US NIH consensus):
≥ 35: surgery is recommended, with or without comorbidityBMI 30–34.9 with hard-to-control type 2 diabetes or metabolic syndrome: surgery should be consideredAsian patients with BMI ≥ 27.5: the surgical option should be offered (at the same BMI, Asian people carry more visceral fat, so the threshold is lowered)The hard upper age limit was dropped in favor of individual assessment (evidence in both adolescents and older adults is growing)The hard precondition of first trying lifestyle change for a fixed period was dropped (it tended to push patients past the best moment)
China's own indications (the 2024 obesity diagnosis and treatment guideline, the country's first national clinical guideline on obesity): age 18–70 with BMI ≥ 32.5; or BMI ≥ 27.5 with type 2 diabetes, and this line states explicitly whether or not medical treatment of the diabetes has worked. BMI between 27.5 and 32.5 where medical weight management has failed, or with another obesity-related disease that medical treatment has not controlled, is also within the indications.
Set the two side by side, and the arithmetic of subtracting 2.5 for Asian patients in the international statement lands exactly on the numbers the Chinese guideline writes down (35−2.5 = 32.5, 30−2.5 = 27.5). The difference is not in the values; it is that a Chinese reader does not have to do the subtraction. And the Chinese guideline puts back one thing the international statement removed: an age range of 18 to 70 (above 70, a multidisciplinary discussion is required).
Why the widening: 30 years of follow-up data have accumulated, and death within 30 days of modern laparoscopic surgery at standardized centers is now uncommon, so the risk of the operation is now lower than that of untreated obesity. The current international consensus is that in suitable patients, earlier brings more benefit than later.
Chapter 2
How surgery changes hunger hormones
The key difference between surgery and dieting lies in the gut hormones.
The upper part of the stomach, the fundus, is the main source of ghrelin, the hormone that makes you feel hungry. Sleeve gastrectomy removes the fundus and gastric bypass separates it from the path food takes, so ghrelin stays low: in a small study (Cummings 2002), people who had had gastric bypass had ghrelin 72% lower than obese controls of similar weight, and the rise before meals had disappeared. For patients, hunger really does weaken; it is not a matter of holding out on willpower. At the same time, food reaches the lower small intestine faster, and the cells there release more satiety signals such as and PYY. That is also why blood glucose often improves before much weight has come off.
Dieting alone does the opposite: in the same study, people who lost 17% of their body weight by dieting saw their ghrelin rise by 24%. The body switches on its hunger defense, and once the diet stops, the weight tends to bounce back.
The upper part of the stomach, the fundus, is the main source of ghrelin, the hormone that makes you feel hungry. Sleeve gastrectomy removes the fundus and gastric bypass separates it from the path food takes, so ghrelin stays low: in a small study (Cummings 2002), people who had had gastric bypass had ghrelin 72% lower than obese controls of similar weight, and the rise before meals had disappeared. For patients, hunger really does weaken; it is not a matter of holding out on willpower. At the same time, food reaches the lower small intestine faster, and the cells there release more satiety signals such as and PYY. That is also why blood glucose often improves before much weight has come off.
Dieting alone does the opposite: in the same study, people who lost 17% of their body weight by dieting saw their ghrelin rise by 24%. The body switches on its hunger defense, and once the diet stops, the weight tends to bounce back.
Mechanism · How hormones change after surgery
The core hormone changes (clear after both gastric bypass and sleeve gastrectomy, larger after bypass):Ghrelin falls sharply: ghrelin comes mostly from the gastric fundus. Sleeve gastrectomy removes the fundus and gastric bypass separates it from the path of food, so plasma ghrelin stays low. The patient's hunger genuinely weakens; it is no longer a matter of holding out on willpower. The classic evidence is Cummings 2002 (NEJM): in 5 people after gastric bypass, compared with obese controls of similar weight, the area under the 24-hour ghrelin curve was 72% lower, and its rise and fall with the three meals had vanished; that study measured ghrelin only (glucagon-like peptide-1) rises: food reaches the far end of the small intestine quickly and stimulates the L cells there, and GLP-1 risesPYY (peptide YY) rises: it also comes from the distal L cells and reinforces the satiety signalBile-acid metabolism changes: the bile-acid pathway is remodeled, and one hypothesis is that, acting through two kinds of receptor called FXR and TGR5, it improves insulin sensitivity and shifts the gut floraThe gut microbiome reorganizes: after surgery, Bacteroidetes have been observed to increase and Firmicutes to decrease, with more short-chain fatty acids produced
Why diabetes often remits before much weight has come off:
It has been observed again and again in clinic: within days of gastric bypass, before the patient has visibly slimmed, blood glucose improves markedly, and some patients stop insulin before they leave the hospitalThe usual explanation is the hormone changes above, above all the large rise in GLP-1 and the remodeling of the signaling axis between the gut and the pancreatic islets. This observation gave rise to the name metabolic surgery, which insists that at heart it is treating a metabolic disease by changing anatomy, not only weight lossIn of surgery plus intensive medical therapy against medical therapy alone, remission was higher in the surgical arm, but that arm also lost considerably more weight, so the weight of the two groups was not matched. SOS 2007 is a matched cohort whose primary endpoint was all-cause mortality, not a randomized trial of diabetes remission
The key difference from dieting alone:
Weight loss by diet: ghrelin rises instead (the body switches on its hunger defense), leptin falls, and the weight tends to come back. Sumithran 2011 (NEJM) put 50 adults with overweight or obesity and without diabetes on a very-low-calorie diet; at 62 weeks, leptin, ghrelin, PYY and several other appetite-related hormones still differed from their levels before the diet. That study did not measure energy expenditureWeight loss by surgery: ghrelin falls and stays low, while GLP-1 and PYY rise and stay high. One explanation is that the body's weight set-point has been moved down; the set-point is a model, not something measured directlyThat difference may explain why weight lost through surgery holds, while diet or drugs tend to rebound once stopped
Where the mechanism stops:
Surgery does not abolish every compensation: some weight comes back by five years, and diabetes returns in some patientsBut compared with dieting or drugs, the regain is much smaller and the effect lasts much longerGLP-1 drugs mimic part of the hormonal effect of surgery, but most people regain weight after stopping them, whereas the anatomical change from surgery is permanent
Chapter 3
Results decades later
Sweden's SOS study is the most important long-term study in the evidence on bariatric surgery: 4047 people with severe obesity, about half of whom had surgery while the other half received usual care as controls, followed for an average of 10.9 years. It was not a randomized trial; the two groups were matched on their starting characteristics.
The result: weight loss in the surgical group held for the long term, while the controls' weight changed by less than 2%; the surgical group's risk of death from any cause was 29% lower (an adjusted , HR, of 0.71). No diet or exercise intervention has ever lowered a such as death this much.
One explanation: when you rely on dieting alone, the body switches on its hunger defense and wins back the weight you lost; surgery changes the gut hormones, and that defense becomes much weaker. People in the surgical group kept the weight off not because they had stronger willpower.
The result: weight loss in the surgical group held for the long term, while the controls' weight changed by less than 2%; the surgical group's risk of death from any cause was 29% lower (an adjusted , HR, of 0.71). No diet or exercise intervention has ever lowered a such as death this much.
One explanation: when you rely on dieting alone, the body switches on its hunger defense and wins back the weight you lost; surgery changes the gut hormones, and that defense becomes much weaker. People in the surgical group kept the weight off not because they had stronger willpower.
Evidence · The numbers from the SOS study
The SOS study (Swedish Obese Subjects, Sjöström 2007, NEJM): the most important long-term prospective cohort in weight management.Design:
Sweden, 4047 people with severe obesity ( ≥ 34 in men, ≥ 38 in women), enrolled 1987–20012010 in the surgical group and 2037 in the usual-care control group, matched on 18 baseline variablesMean follow-up of 10.9 years (later extended beyond 20 years)Note: it is not a randomized trial (it would not be ethical to randomize people with severe obesity to a group left untreated for decades), but the matching is strict, and it is the weightiest long-term data on this questionNote also: the SOS surgical group had gastric bypass, vertical banded gastroplasty or gastric banding, and the last two are rarely used today; sleeve gastrectomy, the most common operation now, was not among them
Hard endpoints:
Weight: controls changed by less than ±2% over the long term. The surgical group lost most at 1–2 years after surgery: 32% with gastric bypass, 25% with vertical banded gastroplasty, 20% with banding; at 10 years these had settled at 25%, 16% and 14%. Later SOS papers report that at 20 years the surgical group was still about 18% below its starting weightAll-cause mortality: 29% lower in the surgical group (adjusted , HR, 0.71); 129 deaths among controls and 101 in the surgical groupThe following come from later SOS papers, and all are observed associations:New type 2 diabetes: about 83% lower in the surgical group (adjusted HR 0.17, Carlsson 2012)Cardiovascular events (first heart attack or stroke, fatal plus nonfatal): 33% lower in the surgical group (HR 0.67)Cancer incidence (women): 42% lowerMicrovascular complications (in people who had type 2 diabetes at baseline): 56% lower
No diet or exercise intervention has lowered such as death and cardiovascular events this much: in Look AHEAD, a randomized trial of intensive lifestyle intervention in type 2 diabetes, cardiovascular events were not reduced. Among drugs, semaglutide cut major cardiovascular events by about 20% in people with established cardiovascular disease and without diabetes (the SELECT trial), but it has never been compared directly with surgery.
Randomized trials focused on diabetes remission (STAMPEDE at 5 years, DSS at 10 years, and trials by Mingrone and others):
Complete remission (, HbA1c, below 6% with no glucose-lowering drugs) was clearly more common in the surgical groups than in the intensive medical therapy groupsIn the intensive medical therapy groups, complete remission was rareEven where diabetes partly returned later, glucose control and medication burden stayed clearly better in the surgical groups
Compared with drugs:
Semaglutide (STEP 1, Wilding 2021): 2.4 mg by weekly injection for 68 weeks cut body weight by 14.9% on average, against 2.4% with placebo; people with diabetes were not includedTirzepatide (SURMOUNT-1, Jastreboff 2022): after 72 weeks, weight fell by 15.0% to 20.9% depending on dose, against 3.1% with placebo; people with diabetes were likewise excludedBariatric surgery: in SOS, gastric bypass took off up to 32% at 1–2 years and still 25% at 10 yearsWith drugs, weight comes back once they stop: in the STEP 1 extension, about 2/3 of the lost weight returned within a year of stopping (Wilding 2022), whereas weight lost through surgery holdsA common clinical view: drugs are a first-line choice for many people (especially at BMI 30–40), and surgery is the stronger tool for heavier obesity or more severe metabolic disease. The two are not mutually exclusive; they are rungs on one ladder
SOS also warns:
Not every subgroup benefits equally: those with the most severe metabolic disease at baseline benefit mostLong follow-up also exposed costs such as alcohol misuse, suicide risk and nutritional deficiency, which the later chapter on the risks and lifelong costs of surgery covers in detail
carlsson-2012-sos-diabetes-prevention
Chapter 4
Risks and lifelong costs
Bariatric surgery is not lying back and getting thin. It is a major intervention with a clear price: the risk of the operation itself, lifelong nutrient deficiencies, and psychological and behavioral risks, and none of them can be skipped.
The item most easily overlooked: the largest part of that price is paid not on the day of surgery but over the rest of your life after it. Gastric bypass routes food past the key sites where B12, iron and calcium are absorbed, so B12, iron, calcium and vitamin D must be supplemented for life, with regular checkups for life. If you will not accept that lifelong follow-up, you should not have the operation.
After surgery, if you develop fever, a racing heart, or abdominal pain that keeps getting worse, or become confused or unsteady on your feet after severe vomiting, get medical care immediately.
The item most easily overlooked: the largest part of that price is paid not on the day of surgery but over the rest of your life after it. Gastric bypass routes food past the key sites where B12, iron and calcium are absorbed, so B12, iron, calcium and vitamin D must be supplemented for life, with regular checkups for life. If you will not accept that lifelong follow-up, you should not have the operation.
After surgery, if you develop fever, a racing heart, or abdominal pain that keeps getting worse, or become confused or unsteady on your feet after severe vomiting, get medical care immediately.
Safety · Complications, deficiencies, mental health
1. Risk of the operation itself (modern laparoscopic surgery at a standardized center):30-day mortality is low, but not zeroMajor complications: anastomotic leak (the most dangerous one after gastric bypass), bleeding, deep-vein thrombosis and pulmonary embolism, narrowing at an incision or join, and internal hernia (a long-term complication of gastric bypass)Reoperation: some people need revision or treatment of a complication in the years after surgeryMortality is closely tied to how many operations a center performs: at low-volume centers the risk rises markedlyFever, a racing heart or worsening abdominal pain after surgery may mean an anastomotic leak; get medical care immediately
2. Long-term nutritional deficiency (for life):
Vitamin B12 deficiency: gastric bypass skips the region that secretes stomach acid and intrinsic factor, so B12 must be supplemented for life (1000 µg a day by mouth, or by injection). Without it, nerve damage follows, and it can be irreversibleIron deficiency: the duodenum is the main site of iron absorption and gastric bypass skips it, so iron-deficiency anemia is common, especially in women, and iron is needed for lifeCalcium and vitamin D deficiency, leading to bone loss: in the years after gastric bypass, falls markedly and hip-fracture risk rises; calcium at 1200–1500 mg and vitamin D at 3000 a day are required for lifeVitamins A, E and K and thiamine (B1): the risk is highest after biliopancreatic diversion and intermediate after gastric bypass. Acute thiamine deficiency causes Wernicke encephalopathy (especially with severe vomiting after surgery); confusion, unsteady walking or abnormal eye movements after severe vomiting call for medical care immediatelyToo little protein: the stomach holds less, so at least 60 g of protein a day is required (the guideline's upper figure is 1.5 g per kg of ideal body weight); falling short leads to muscle loss and hair loss
3. Dumping syndrome (more common after gastric bypass):
Early type (15–30 minutes after eating): sugary or high-carbohydrate food reaches the small intestine quickly and draws fluid into the gut, causing palpitations, sweating, dizziness, abdominal pain and diarrheaLate type (1–3 hours after eating): reactive hypoglycemia, which in severe cases leads to falls or faintingPatients have to relearn the rhythm of eating (small frequent meals, little sugar, protein first, food and fluids separated)
4. Worsening gastroesophageal reflux disease () (more common after sleeve gastrectomy):
A sizable share of people develop new or worse reflux after sleeve gastrectomy, and some need conversion to gastric bypassGastric bypass, by contrast, tends to improve reflux
5. Psychological and behavioral risk:
Higher risk of alcohol use disorder: SOS follow-up analyses and several cohort studies have observed that its incidence after gastric bypass is higher than before surgery (explanations include faster alcohol absorption and the addiction transfer hypothesis)Higher risk of suicide and self-harm: several studies show a higher rate of self-harm after surgery than in the general population with obesity; the mechanism is not fully understood (body image, relationships and metabolic biochemistry have all been proposed). If thoughts of harming yourself appear after surgery, contact your doctor or a local mental-health crisis line right awayRelationships shift: a large fall in weight often comes with a rebuilding of marriage, work and self-image, and studies have observed a rise in divorceThat is why international guidelines require a psychological assessment before surgery and long-term psychological follow-up after it
6. Weight regain:
After weight bottoms out 1–2 years after surgery, some of it comes back (in SOS, gastric bypass went from a maximum loss of 32% to 25% at 10 years)It is still far better than drugs or lifestyle change alone, and the net benefit persistsHow much returns is closely linked to eating habits, activity, psychological state, and whether a drug is used alongside
7. Lifelong follow-up:
First year after surgery: the most frequent visits, including nutritional markers and a psychological assessmentAfter that, at least once a year for life: B12, iron, calcium, vitamin D, parathyroid hormone () and proteinBone density: once before surgery as a baseline, then again at about 2 yearsIf you will not accept that lifelong follow-up, you should not have the operation
Chapter 5
Who should consider it, who shouldn't
See surgery as the strongest end of the intervention ladder: not the first option and not the last, but the most powerful tool for a specific group of people.
The people who should seriously consider it have true severe obesity and have already made a systematic attempt with lifestyle change and drugs (including drugs) without bringing it under control. The people who should not have it are those who just want to lose a few kilos for their looks, or who are not ready for lifelong follow-up and nutritional supplements.
A psychological assessment comes before surgery. Active alcohol or drug misuse, uncontrolled severe mental illness, and plans for pregnancy within the next year or so all need to be dealt with first.
The people who should seriously consider it have true severe obesity and have already made a systematic attempt with lifestyle change and drugs (including drugs) without bringing it under control. The people who should not have it are those who just want to lose a few kilos for their looks, or who are not ready for lifelong follow-up and nutritional supplements.
A psychological assessment comes before surgery. Active alcohol or drug misuse, uncontrolled severe mental illness, and plans for pregnancy within the next year or so all need to be dealt with first.
Clinical · Who fits and who does not
Worth considering surgery (several of the following apply):≥ 35, with or without comorbidity (the 2022 ASMBS/IFSO standard; the old 1991 criteria required BMI ≥ 40, or BMI ≥ 35 plus a comorbidity such as type 2 diabetes, hypertension, obstructive sleep apnea, metabolic dysfunction-associated steatohepatitis (MASH) or severe joint load)BMI ≥ 30 with hard-to-control type 2 diabetes (, HbA1c, still poorly controlled after ≥ 6 months of guideline drug therapy), the group newly opened up in 2022Asian patients with BMI ≥ 27.5: the surgical option should be offered (ASMBS/IFSO 2022); China's guideline uses BMI ≥ 32.5, or ≥ 27.5 with type 2 diabetesHas already made a systematic attempt with structured lifestyle intervention and drugs (including a drug where cost and contraindications allow) without a sustained, meaningful result (the 2022 statement no longer requires a fixed trial period first)Psychologically stable on assessment: understands what the operation means and can carry lifelong follow-up and lifelong nutritional supplementsUnderstands that surgery is not the finish line: changed eating habits, exercise and psychological work come with it; they are not optionalSupport system in place: family, finances and access to care that can hold for 5–10 years
Not suitable (absolute or relative contraindications):
Treating surgery as quick cosmetic work: appearance is the only motive and the long-term price is not understood; strongly advised againstUnwilling to take lifelong supplements and attend follow-up: the price of skipping B12, iron, calcium and vitamin D is irreversible nerve damage and fracturesActive substance misuse (alcohol, opioids, benzodiazepines and so on): surgery amplifies alcohol-related risk, so this must be stabilized firstUncontrolled severe mental illness (active psychosis, severe untreated depression, an eating disorder): treat until stable firstPregnancy planned in the near future (within 12–18 months): the period of rapid weight change after surgery is not a time to conceive, and nutritional deficiency affects the fetusLife expectancy limited by another severe disease, leaving too short a window for benefitUnable to follow the change in eating after surgery: the chance of technical failure is high
A realistic frame for anyone hesitating:
Not having surgery is not the same as staying where you are: untreated severe obesity carries a high long-term cost (type 2 diabetes, cardiovascular disease, cancer, joints). In the Global BMI Mortality Collaboration's 2016 individual-participant in the Lancet (239 prospective studies), among never-smokers without chronic disease at enrollment, and compared with a BMI of 22.5–25, the risk of death from any cause was 1.94 times as high at BMI 35–40 and 2.76 times as high at BMI 40–60What is really being compared is operative risk, lifelong supplements and psychological adjustment against untreated severe obesity, accumulating comorbidity and a higher risk of deathFor people who genuinely meet the indications, guidelines hold that earlier brings more benefitFor people who do not (BMI 25–30, wanting to lose 5 kg, for appearance), do not do it: the risks and benefits are out of proportion
How it relates to the rung below (GLP-1 drugs):
A common path now is lifestyle change, then a GLP-1 drug (for six months to a few years), then reassessment; for many people the drug is enoughIf the GLP-1 drug is not enough (less than 10% weight loss with comorbidities unimproved), or weight rebounds whenever the drug stops and long-term use is unaffordable, the next step is a surgical assessmentSome people take a low-dose GLP-1 drug after surgery to handle partial regain; the two are not mutually exclusive
Connected topics:
Weight Management (energy balance, how body weight is regulated)Leptin Resistance & Body-Weight Set-Point (why dieting rebounds, and why surgery may lower the set-point)GLP-1 agonists (the rung below)Type 2 Diabetes & Prediabetes (the main comorbidity, and where the benefit is largest)nafld (metabolic dysfunction-associated steatotic liver disease, , often comes with obesity, and ≥ 10% weight loss is also its first-line treatment)
References · 12
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- The Global BMI Mortality Collaboration. (2016). Body-mass index and all-cause mortality: Individual-participant-data meta-analysis of 239 prospective studies in four continents. The Lancet, 388(10046), 776–786. IPD from 239 prospective studies (10.6 million people); primary analyses in 3.95 million never-smokers without chronic disease who survived 5 years. All-cause mortality lowest at BMI 20.0-25.0; HR 1.13 at 18.5-20, 1.51 at 15-18.5, 1.07 at 25-27.5, 1.20 at 27.5-30, 1.45 at 30-35, 1.94 at 35-40, 2.76 at 40-60; per 5 units above 25, HR 1.39 in Europe and east Asia, 1.29 North America, 1.31 Australia/NZ; stronger in younger people and men (abstract, PMID 27423262). 10.1016/S0140-6736(16)30175-1
- General Office of the National Health Commission of China. (2024). Guideline for the diagnosis and treatment of obesity (2024 edition). Issued 2024-10. China's first national clinical obesity guideline. Classification for Chinese adults: BMI 24 up to 28 is overweight and 28 or above is obesity, subdivided as mild 28.0 up to 32.5, moderate 32.5 up to 37.5, severe 37.5 up to 50. Central obesity: waist circumference is normal below 85 cm in men and 80 cm in women, and central obesity is diagnosed at 90 cm or more in men and 85 cm or more in women; a waist-hip ratio of 0.90 or more in men and 0.85 or more in women also establishes it. Weight-loss target: for most overweight and mildly obese patients, at least 5 to 15 percent of body weight within 3 to 6 months, then maintained, with reassessment every 3 to 6 months. Pharmacotherapy is indicated by clinical state rather than by a BMI number: overweight plus at least one weight-related comorbidity (hyperglycaemia, hypertension, dyslipidaemia, fatty liver, obstructive sleep apnoea, cardiovascular disease) where lifestyle intervention fails to reach the target, or obesity where lifestyle intervention fails to reach the target. Five drugs are approved in China for weight reduction in adult primary obesity: orlistat, liraglutide, beinaglutide, semaglutide and tirzepatide. Surgical indications: ages 18 to 70 with BMI 32.5 or above, or BMI 27.5 or above with type-2 diabetes regardless of whether medical treatment has succeeded; also ages 18 to 70 with BMI from 27.5 up to 32.5 where medical weight reduction has failed or an obesity-related disease is refractory to medical treatment. SCOPE NOTE: chapter 12 is traditional-Chinese-medicine treatment (syndrome differentiation, daoyin exercises), which is outside this site's content scope and is not cited anywhere. www.gov.cn/zhengce/zhengceku/202410/content_6981734.htm
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- Wilding, J. P. H., Batterham, R. L., Calanna, S., Davies, M., Van Gaal, L. F., Lingvay, I., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity (STEP-1). New England Journal of Medicine, 384(11), 989-1002. 1961 adults with BMI >= 30 (or >= 27 with a weight-related condition) and no diabetes, randomized 2:1 to semaglutide 2.4 mg weekly or placebo, plus lifestyle intervention, for 68 weeks. Mean body-weight change -14.9% vs -2.4% (difference -12.4 percentage points); >= 15% loss in 50.5% vs 4.9%; -15.3 kg vs -2.6 kg; discontinuation for gastrointestinal events 4.5% vs 0.8%. Funded by Novo Nordisk (abstract, PMID 33567185). 10.1056/NEJMoa2032183
- Jastreboff, A. M., Aronne, L. J., Ahmad, N. N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M. C., & Stefanski, A. (2022). Tirzepatide once weekly for the treatment of obesity. The New England Journal of Medicine, 387(3), 205–216. 2539 adults with BMI >= 30, or >= 27 with a weight-related complication, people with diabetes excluded; randomized 1:1:1:1 to tirzepatide 5, 10 or 15 mg weekly or placebo for 72 weeks (20-week dose escalation). Mean weight change (treatment-regimen estimand) -15.0%, -19.5% and -20.9% vs -3.1%; >= 20% loss in 50% and 57% on 10 and 15 mg vs 3%. Adverse events led to discontinuation in 4.3%, 7.1% and 6.2% vs 2.6%. Funded by Eli Lilly (abstract, PMID 35658024). 10.1056/NEJMoa2206038
- Wilding, J. P. H., Batterham, R. L., Davies, M., Van Gaal, L. F., Kandler, K., Konakli, K., Lingvay, I., McGowan, B. M., Oral, T. K., Rosenstock, J., Wadden, T. A., Wharton, S., Yokote, K., & Kushner, R. F. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism, 24(8), 1553–1564. 10.1111/dom.14725
- The Look AHEAD Research Group. (2013). Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes. The New England Journal of Medicine, 369(2), 145–154. 5,145 overweight or obese adults with type 2 diabetes randomized to an intensive lifestyle intervention or diabetes support and education. Stopped early for futility at a median follow-up of 9.6 years. Weight loss 8.6% vs 0.7% at 1 year and 6.0% vs 3.5% at study end. Primary composite (cardiovascular death, nonfatal MI, nonfatal stroke, hospitalized angina): 403 vs 418 events, HR 0.95 (0.83-1.09), P = 0.51 - cardiovascular events were not reduced (abstract, PMID 23796131). 10.1056/NEJMoa1212914
- Lincoff, A. M., Brown-Frandsen, K., Colhoun, H. M., et al. (2023). Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). New England Journal of Medicine, 389(24), 2221-2232. In 17,604 adults with overweight/obesity and established cardiovascular disease but without diabetes, semaglutide 2.4 mg reduced major adverse cardiovascular events by 20% (HR 0.80; 6.5% vs 8.0%). 10.1056/NEJMoa2307563
- Mechanick, J. I., Apovian, C., Brethauer, S., Garvey, W. T., Joffe, A. M., Kim, J., Kushner, R. F., Lindquist, R., Pessah-Pollack, R., Seger, J., Urman, R. D., Adams, S., Cleek, J. B., Correa, R., Figaro, M. K., Flanders, K., Grams, J., Hurley, D. L., Kothari, S., … Still, C. D. (2020). Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures - 2019 update: cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists. Surgery for Obesity and Related Diseases, 16(2), 175-247. Published jointly in Endocrine Practice (2019) and Obesity (2020); 85 numbered recommendations, 41% of the statements Grade D. R38 (Grade D): protein intake individualized and guided by a dietitian; a minimal protein intake of 60 g/d and up to 1.5 g/kg ideal body weight per day should be adequate, with up to 2.1 g/kg assessed individually (the guideline gives no 60-80 g range). R39, minimal daily supplementation after sleeve gastrectomy and Roux-en-Y gastric bypass: 2 adult multivitamins plus minerals, elemental calcium 1,200 to 1,500 mg/d (1,800 to 2,400 mg/d after biliopancreatic diversion with duodenal switch) in diet and as citrated supplement in divided doses (Grade B), at least 2,000 to 3,000 IU of vitamin D titrated to 25-hydroxyvitamin D above 30 ng/mL (Grade A; the postprocedure checklist, Table 9, says at least 3,000 units/d), total iron 18 to 60 mg, and vitamin B12. R60: B12 checked at baseline and annually in all patients, more often (e.g., every 3 months) in the first postoperative year; oral crystalline B12 350 to 1,000 µg daily or more to maintain normal levels (Grade A); parenteral 1,000 µg/month to 1,000 to 3,000 µg every 6 to 12 months if oral or intranasal routes fail. R54 (Grade D): after gastric bypass or biliopancreatic diversion, spine and hip DXA may be indicated at baseline and at about 2 years (Table 9: bone density at 2 years; no every-2-years interval is stated). Table 9 follow-up visits after gastric bypass: 1 month, then every 3 months until stable, then every 6-12 months. The task-force chair disclosed Abbott Nutrition honoraria (full text read in the Endocrine Practice version; abstract, PMID 31917200). 10.1016/j.soard.2019.10.025