ACRONYMS AND DEFINITIONS

AGA - American Gastroenterological Association

ASMBS - The American Society for Metabolic and Bariatric Surgery

BMD - Bone mineral density

BPD/DS - Biliopancreatic diversion with duodenal switch

DVT - Deep vein thrombosis

ESG - Endoscopic sleeve gastroplasty

GERD - Gastroesophageal reflux disease

NAFLD - Nonalcoholic fatty liver disease

NASH - Nonalcoholic steatohepatitis

PCOS - Polycystic ovary syndrome

RYGB - Roux-en-Y gastric bypass (Gastric bypass)

SADI-S - Single anastomosis duodeno–ileal bypass with sleeve gastrectomy

SR - Silastic ring

VTE - Venous thromboembolism

PROCEDURE RATES

Overview

Weight loss procedures have become increasingly common. In 2020, around 300,000 bariatric surgeries were performed in the U.S., which is equal to the number of cholecystectomies performed annually.
The two most common procedures are gastric sleeve and gastric bypass (also called Roux-en-Y gastric bypass). Gastric bypass used to be the most common procedure, but around 2013, gastric sleeve surpassed it. Today, more than 60% of bariatric surgeries are gastric sleeve procedures, while gastric bypass makes up less than 20%. Reasons that gastric sleeve has become preferred include lower surgical complication rates, lower reoperation rates, and fewer chronic nutritional deficiencies.
In 2019, an estimated 256,000 weight loss procedures were performed in the U.S.. The table below gives a breakdown of which procedures were performed.

^✝Revisons of previous weight loss procedures

Reference: **ASMBS website**
Type of weight loss procedure performed in U.S. in 2019 (N=256,000 procedures)
Gastric sleeve	59.4%
Gastric bypass	17.8%
Revisional surgery^✝	16.7%
Gastric balloon	1.8%
Gastric banding	0.9%
BPD/DS	0.9%
Other	2.4%

WEIGHT LOSS EFFECTS

PDF version of table

References [1 - 9,13]
Typical weight loss seen with obesity treatments
Treatment	% weight loss from baseline (length of follow-up)
BPD/DS	35 - 40% (> 10 years)
Gastric bypass	30 - 35% (> 10 years)
Gastric sleeve	25 - 30% (> 10 years)
Gastric banding	20 - 25% (> 10 years)
Wegovy (semaglutide)	16% (68 weeks)
Endoscopic sleeve gastroplasty	11.4% (104 weeks)
Intragastric balloon	10% (6 months)
Appetite suppressants (e.g. phentermine)	10% (6 months)
Qsymia (topiramate + phentermine)	10% (56 weeks)
Saxenda (Liraglutide)	8% (56 weeks)
Xenical (orlistat)	7.6% (2 years)
Contrave (naltrexone + bupropion)	6.5% (28 weeks)
Plenity (hydrogel)	6.4% (24 weeks)

INDICATIONS

ASMBS indications for bariatric procedures

BMI ≥ 40 - any patient without coexisting medical problems who are not at excessive risk for surgical complications

BMI ≥ 35 - patients with ≥ 1 severe obesity-related complication that is treatable with weight loss. Obesity-related complications include the following: type 2 diabetes, high risk for type 2 diabetes (insulin resistance, prediabetes, and/or metabolic syndrome), poorly controlled hypertension, NAFLD or NASH, obstructive sleep apnea, osteoarthritis of the knee or hip, and urinary stress incontinence. Other conditions that may also be considered but have weaker evidence for a benefit include the following: obesity-hypoventilation syndrome and Pickwickian syndrome after a careful evaluation of operative risk, idiopathic intracranial hypertension, GERD, severe venous stasis disease, impaired mobility due to obesity, and considerably impaired quality of life.

BMI 30 - 34.9 - patients with type 2 diabetes and inadequate glycemic control despite optimal lifestyle and medical therapy should be considered for a bariatric procedure

The BMI criterion for bariatric procedures should be adjusted for ethnicity (e.g. for Asians: 18.5 – 22.9 is healthy range; 23 – 24.9 overweight; and ≥ 25 obese) [1]

PREPROCEDURAL EVALUATION

The ASMBS recommends the following workup in patients who are being considered for bariatric procedures

Complete history and physical including psychological evaluation
Nutritional evaluation by a registered dietician
Lab work

All patients

CBC, CMP, Lipid profile, TSH, Urinalysis, PT/INR, Blood type
Iron studies
Vitamin B12
Folic acid (RBC folate, homocysteine, methylmalonic acid are optional)
Vitamin D

Certain patients

Hemoglobin A1C if diabetic or prediabetic
Vitamin A and E - consider in patients undergoing BPD/DS or RYGB
Whole-blood thiamine (B1) levels may be considered in patients before bypass procedures (RYGB and BPD/DS)
PCOS workup if clinically indicated (free and total testosterone, DHEA-S, and 17-hydroxyprogesterone (17-OHP))
Cushing's syndrome screening if clinically indicated (e.g. 1-mg overnight dexamethasone test, 24-hour urinary free cortisol, 11 PM salivary cortisol)
H. pylori testing in areas of high prevalence

ECG (also consider ECHO in appropriate patients)
Sleep study
Liver evaluation and/or upper endoscopy, if clinically indicated (e.g. elevated LFTs, symptoms of cholelithiasis)
Complete all recommended cancer screening
Estrogen therapy should be discontinued before a bariatric procedure (1 cycle of oral contraceptives in premenopausal women; 3 weeks of hormone replacement therapy in postmenopausal women) to reduce the risks for postprocedure VTE
Patients who smoke cigarettes should stop as soon as possible, preferably 1 year, but at the very least, 6 weeks before bariatric procedures
Patients with a history of DVT or cor pulmonale should be evaluated for ongoing DVT [1]

POSTOPERATIVE CARE

PDF version of table

References [1,10,11]
Bariatric procedure long-term maintenance care
Gastric sleeve Labs (annually in all patients) CBC, CMP, Lipid profile Vitamin B12 Vitamin D Iron studies Other Avoid NSAIDs if possible. If taken, give with proton pump inhibitor (PPI). History of kidney stones - consider 24-hr urinary calcium excretion Bone mineral density (BMD) two years after procedure Long-term complications May worsen or cause new onset GERD Gallstones (from rapid weight loss) Sleeve stricture Incisional hernia Osteoporosis
Gastric bypass (RYGB) Labs (annually in all patients) CBC, CMP, Lipid profile Vitamin B12 Vitamin D Folic acid Iron studies Zinc (serum and plasma levels) Copper (serum copper and ceruloplasmin) Other Avoid NSAIDs if possible. If taken, give with proton pump inhibitor (PPI). History of kidney stones - consider 24-hr urinary calcium excretion Bone mineral density (BMD) two years after procedure Long-term complications Malabsorption Dumping syndrome Gallstones (from rapid weight loss) Anastomotic strictures Bowel obstruction Marginal ulceration Gastrogastric fistula Incisional and internal hernias Osteoporosis
Gastric banding Labs (annually in all patients) CBC, CMP, Lipid profile Vitamin B12 Vitamin D Iron studies Other Avoid NSAIDs if possible. If taken, give with proton pump inhibitor (PPI). History of kidney stones - consider 24-hr urinary calcium excretion Bone mineral density (BMD) two years after procedure Long-term complications Band slippage over stomach Band erosion through stomach Swallowing problems Enlargement of esophagus Osteoporosis
Biliopancreatic diversion with duodenal switch (BPD/DS) Labs (annually in all patients) CBC, CMP, Lipid profile Vitamin B12 Vitamin D Vitamin A Folic acid Iron studies Zinc (serum and plasma levels) Copper (serum copper and ceruloplasmin) 24-hour urinary calcium excretion at 6 months post-op and annually Other Avoid NSAIDs if possible. If taken, give with proton pump inhibitor (PPI). Bone mineral density (BMD) two years after procedure Long-term complications Malabsorption Dumping syndrome May worsen or cause new onset GERD Loose and frequent stools Gallstones (from rapid weight loss) Kidney stones (from hyperoxaluria, low urinary volume, and hypocitraturia) Bowel obstruction Incisional hernias
Pregnant patients Patients who become pregnant after bariatric procedures should have increased surveillance for nutritional deficiencies during pregnancy Check the following labs in all patients every trimester Vitamin B12 Vitamin D Calcium Folic acid Iron studies For patients who have undergone RYGB or BPD/DS, also include: Vitamin A Vitamin E Vitamin K Zinc (serum and plasma levels) Copper (serum copper and ceruloplasmin)

Reference [1]
Vitamin and mineral recommendations
Vitamin B1 (thiamine) Prevalence of deficiency Up to 49% of patients, depending on procedure and length of follow-up Screening Screen high-risk groups during the first 6 months and every 3 - 6 months as needed High-risk groups include the following: Females Blacks Patients not attending a nutritional clinic after surgery Patients with GI symptoms (intractable nausea and vomiting, jejunal dilation, megacolon, or constipation) Patients with concomitant conditions, such as cardiac failure (especially those receiving furosemide) Patients with small bowel bacterial overgrowth Other risk factors such as malnutrition, excessive and/or rapid weight loss, and excessive alcohol use increase the risk of thiamine deficiency Prevention All patients should consume ≥ 12 mg of thiamine daily, preferably as 50 - 100 mg/day from a B-complex supplement or high-potency multivitamin Treatment Oral: 100 mg 2 - 3 times daily until symptoms resolve IM: 250 mg once daily for 3–5 d or 100–250 mg monthly Magnesium, potassium, and phosphorus should be given simultaneously to patients at risk for refeeding syndrome
Vitamin B12 (cobalamin) Prevalence of deficiency Gastric bypass (2 - 5 years post-op): < 20% Gastric sleeve (2 - 5 years post-op): 4 - 20% Screening Screen all patients annually For patients who take medications that can lower B12 levels (e.g. nitrous oxide, neomycin, metformin, colchicine, proton-pump inhibitors, seizure medications), screen every 3 months in the first year and then annually See vitamin B12 deficiency diagnosis Prevention (all patients) One of the following: Oral supplement (disintegrating tablet, sublingual, or liquid) with 350 - 1000 mcg daily Nasal spray as directed by manufacturer Parenteral (IM or SQ): 1000 mcg monthly Treatment See treatment of B12 deficiency
Folic acid (folate) Prevalence of deficiency Up to 65% of patients Screening Screening is recommended in all patients, particularly after RYGB or BPD/DS and in women of childbearing potential Guidelines do not give a recommended interval Prevention (all patients) 400 - 800 mcg daily in a multivitamin Women of childbearing potential should receive 800 - 1000 mcg/day Treatment Folic acid 1000 mcg daily until levels become normal, then resume normal supplementation
Iron Prevalence of deficiency BPD/DS: up to 62% RYGB: 20 - 55% Gastric sleeve: < 18% Gastric balloon: 14% Screening Screen all patients within 3 months after surgery, every 3 - 6 months until 12 months post-op, then annually Screening labs should include ion studies, ferritin, CBC, and soluble transferrin receptor (if available) Prevention Males and patients without a history of anemia: 18 mg of iron from a multivitamin Menstruating females and patients who have undergone RYGB, gastric sleeve, or BPD/DS: 45 - 60 mg of elemental iron daily (cumulatively, including iron from all vitamin and mineral supplements) Treatment See iron replacement
Vitamin D and calcium Prevalence of deficiency Up to 100% of patients Screening Gastric sleeve, RYGB, BPD/DS: screen annually Recommended vitamin D assay is 25-hydroxyvitamin D (calcidiol) Prevention Calcium (recommended amount from all sources) BPD/DS: 1800 - 2400 mg/day Gastric band, gastric sleeve, RYGB: 1200 - 1500 mg/day Vitamin D Vitamin D level < 30 ng/ml: vitamin D₃ 3000 IU once daily Treatment Calcium (supplement) BPD/DS: 1800 - 2400 mg/day Gastric band, gastric sleeve, RYGB: 1200 - 1500 mg/day Vitamin D Vitamin D₃ 3000 - 6000 IU daily, or vitamin D₂ 50,000 IU one to three times weekly
Vitamin A Prevalence of deficiency Mostly seen after BPD/DS (up to 70% of patients within 4 years post-op) Screening BPD/DS and RYGB: screen within the first post-op year and as needed Prevention RYGB and gastric sleeve: 5000 - 10,000 IU/day Gastric band: 5000 IU/day BPD/DS: 10,000 IU/day Treatment Without corneal changes: vitamin A 10,000 – 25,000 IU/day should be given orally until clinical improvement is evident With corneal changes: vitamin A 50,000 - 100,000 IU/day intramuscularly for 3 days, followed by 50,000 IU/day intramuscularly for 2 weeks Evaluate for concurrent iron and/or copper deficiencies because these can impair the resolution of vitamin A deficiency
Vitamin E Prevalence of deficiency Uncommon Screening Only recommended if patients have symptoms of deficiency which include loss of feeling in the arms and legs, loss of body movement control, muscle weakness, and vision problems Prevention 15 mg/day Treatment 100 - 400 IU/day
Vitamin K Prevalence of deficiency Uncommon Screening Only recommended if patients have symptoms of deficiency which include excessive bleeding or bruising Prevention BPD/DS: 300 mcg/day RYGB and Gastric sleeve: 90 - 120 mcg/day Gastric banding: 90 - 120 mcg/day Treatment Acute malabsorption: 10 mg parenteral Chronic malabsorption: 1 - 2 mg/day orally or 1 - 2 mg/week parenterally
Zinc Prevalence of deficiency BPD/DS: up to 70% RYGB: up to 40% Gastric banding: up to 34% Gastric sleeve: up to 19% Screening Screen RYGB and BPD/DS patients at least annually. Symptoms of zinc deficiency include chronic diarrhea, hair loss, pica, significant dysgeusia, unexplained hypogonadism (males), and erectile dysfunction Zinc is absorbed in the duodenum and proximal jejunum, so procedures that bypass or shorten these areas have a higher risk Serum and plasma zinc levels are the preferred screening method Prevention BPD/DS: multivitamin with minerals containing 200% of the RDA (16 - 22 mg/day) RYGB: multivitamin with minerals containing 100 - 200% of the RDA (8 - 22 mg/day) Gastric sleeve and gastric banding: multivitamin with minerals containing 100% of the RDA (8 - 11 mg/day) The supplementation protocol should contain a ratio of 8 - 15 mg of supplemental zinc per 1 mg of copper to minimize the risk of copper deficiency Treatment There is insufficient evidence to make a recommendation. Repletion doses should be chosen carefully to avoid inducing a copper deficiency.
Copper Prevalence of deficiency BPD/DS: up to 90% RYGB: 10 - 20% Screening Screen RYGB and BPD/DS patients at least annually. Signs of copper deficiency include anemia, neutropenia, myeloneuropathy, and impaired wound healing. Serum copper and ceruloplasmin are recommended biomarkers for determining copper status because they are closely correlated with physical symptoms of copper deficiency Prevention BPD/DS and RYGB: 200% of the RDA (2 mg/day) Gastric sleeve and Gastric banding: 100% of the RDA (1 mg/day) Copper gluconate or sulfate is the recommended source of copper for supplementation Supplementation with 1 mg copper is recommended for every 8 - 15 mg of elemental zinc to prevent copper deficiency Treatment Mild to moderate (including low hematologic indices): 3 - 8 mg/day oral copper gluconate or sulfate until indices return to normal Severe: 2 - 4 mg/day intravenous copper can be initiated for 6 days or until serum levels return to normal and neurologic symptoms resolve Copper levels should be monitored every 3 months after they return to normal
Selenium Prevalence of deficiency Single-anastomosis duodeno-ileal bypass with sleeve: up to 50% Gastric sleeve or gastric banding: up to 16% of patients at 18 months post-op Screening There is insufficient evidence to recommend routine screening. Selenium levels may be checked as part of aggressive case finding in patients with a malabsorptive bariatric surgical procedure who have unexplained anemia or fatigue, persistent diarrhea, cardiomyopathy, or metabolic bone disease. Prevention Oral supplement with greater than 55 mcg/day Treatment No recommendation

GASTRIC SLEEVE

Procedure

Gastric sleeve, also called sleeve gastrectomy, is a procedure where the surgeon removes 80% of the stomach and sutures it back together, leaving a "sleeve" of stomach that is shaped like a banana.

Advantages

Surgery is simpler than gastric bypass and takes less time
Can be performed in certain patients with high-risk medical conditions
May be performed as the first step for patients with severe obesity
May be used as a bridge to gastric bypass or SADI-S procedures
Effective weight loss and improvement of obesity-related conditions

Disadvantages

Non-reversible procedure
May worsen or cause new-onset reflux and heartburn
Less impact on metabolism compared to bypass procedures [11]

SM-BOSS trial - Gastric Sleeve vs Gastric Bypass for Weight Loss Over 5 Years, JAMA (2018) [PubMed abstract]

The SM-BOSS trial enrolled 217 morbidly obese adults in Switzerland

Main inclusion criteria

Age 18 - 65 years
BMI > 40 or > 35 with ≥ 1 comorbidity
Failed conservative treatments for 2 years

Main exclusion criteria

Severe GERD despite meds
Large hiatal hernia
Previous bariatric surgery
Inflammatory bowel disease

Baseline characteristics

Average age 43 years
Female sex - 72%
Average weight - 273 lbs (124 kg)
Average BMI - 44
Type 2 DM - 25%

Randomized treatment groups

Group 1 (107 patients): Laparoscopic sleeve gastrectomy
Group 2 (110 patients): Laparoscopic Roux-en-Y gastric bypass (RYGB)
Treatment was unblinded

Primary outcome: Weight loss, defined as percentage excess BMI loss (100 × [baseline BMI − follow-up BMI]/[baseline BMI − 25]), over a 5-year period

Results

Outcome	Gastric sleeve	RYGB	Comparisons
Duration: 5 years
Weight loss	73 lbs (33 kg)	81 lbs (36.6 kg)	p=0.19
Percent weight loss	25%	28.6%	p=0.02
Primary outcome (excess BMI loss)	61%	68%	p=0.22
Post-op intervention	15.8%	22.1%	N/A
Overall mortality	0%	1.9%	N/A
Weight loss nadir was reached between years 1 and 2 in both groups In the gastric sleeve group, 9 patients underwent conversion to RYGB during follow-up due to GERD

Findings: Among patients with morbid obesity, there was no significant difference in excess BMI loss between laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass at 5 years of follow-up after surgery.

RYGB with Silastic RIng vs Gastric Sleeve for Diabetes Remission at 5 Years, Diabetes Care (2022) [PubMed abstract]

The study enrolled 114 obese adults with types 2 diabetes in New Zealand

Main inclusion criteria

Age 20 - 55 years
Type 2 diabetes for ≥ 6 months
BMI 35 - 65 for ≥ 5 years

Main exclusion criteria

C-peptide < 350 pmol/L
Type 1 diabetes
Current smoker
Chronic pancreatitis

Baseline characteristics

Average age 46 years
Female sex - 52%
Average weight - 275 lbs (125 kg)
Average BMI - 42.8
Average A1C - 7.9%

Randomized treatment groups

Group 1 (56 patients): Silastic ring laparoscopic Roux-en-Y gastric bypass (SR-LRYGB)
Group 2 (58 patients): Laparoscopic sleeve gastrectomy (LSG)
Treatment was double-blinded
SR-LRYGB is gastric bypass with a silastic ring placed around the pouch just above its connection with the jejunum. The ring prevents the pouch from expanding and can increase the long-term success of the procedure.

Primary outcome: A hemoglobin A1C level of < 6% (42 mmol/mol) without any glucose-lowering medications at 5 years (American Diabetes Association criteria for complete remission of type 2 diabetes)

Results

Outcome	SR-LRYGB	LSG	Comparisons
Duration: 5 years
Primary outcome	48%	31%	p=0.015
% weight loss	26.9%	16.3%	p<0.001
Body weight lost	73 lbs (33.3 kg)	46.4 lbs (21.1 kg)	p<0.05
Nadir body weight was reached at 12 months after SR-LRYGB and at 9 months after LSG, after which there was steady mean weight regain to 5 years The early (< 30 days post-op)) minor morbidity rate was 12.5% (N=7) for SR-LRYGB and 5.2% (N=3) for LSG (p=0.20), while early major morbidity rate was 3.6% (N=2) for SR-LRYGB and 8.6% (N=5) for LSG (p=0.44). Late (> 30 days post-op) minor and major complications were 19.6% (N=11) and 12.5% (N=7) after SR-LRYGB versus 12.1% (N=7) and 3.4% (N=2) after LSG (p=0.31 and p=0.09, respectively).

Findings: SR-LRYGB provided superior diabetes remission and weight loss compared with LSG at 5 years, with similar low risks of complications

Summary

In the two studies above, gastric bypass led to greater weight loss than gastric sleeve at 5 years. The difference was more pronounced in the SR-LRYGB study (26.9% vs 16.3%) than in the SM-BOSS study (28.6% vs 25%). The SR-LRYGB study was unique in that participants and researchers were blinded to the procedure that was performed. In both studies, gastric bypass had a slightly higher complication rate. Gastric sleeve was more effective in the SM-BOSS study (25% vs 16.3% weight loss), which took place at 4 bariatric centers in Switzerland; the SR-LRYGB study was a single-center study in New Zealand. Given these differences in demographics and design, it's difficult to make comparisons between the studies.

GASTRIC BYPASS

Procedure

Gastric bypass, also called Roux-en-Y gastric bypass (RYGB), is a procedure where the upper part of the stomach is made into a pouch about the size of an egg. The small intestine is then cut between the duodenum and jejunum, and the jejunum is brought up and connected to the pouch. The remaining stomach and duodenum are connected to the jejunum several feet down from the pouch. Some surgeons perform a variation of the surgery, where a silastic ring is placed around the pouch just above its connection with the jejunum. The ring prevents the pouch from expanding and can increase the long-term success of the procedure (gastric bypass with silastic ring)

Advantages

Causes reliable and long-lasting weight loss
Has been performed for more than 50 years
The procedure treats gastric reflux

Disadvantages

More complex surgery than gastric sleeve
Higher reoperation rate and more chronic vitamin and mineral deficiencies than gastric sleeve
May cause small bowel complications
Increased risk of developing ulcers, especially with NSAID or tobacco use
May cause "dumping syndrome," a condition where food, especially sugars, move into the small bowel too quickly and cause abdominal cramping and diarrhea
If silastic ring is used, erosion of the ring into the stomach can occur [11]

SM-BOSS trial - Gastric Sleeve vs Gastric Bypass for Weight Loss Over 5 Years, JAMA (2018) [PubMed abstract]

The SM-BOSS trial enrolled 217 morbidly obese adults in Switzerland

Main inclusion criteria

Age 18 - 65 years
BMI > 40 or > 35 with ≥ 1 comorbidity
Failed conservative treatments for 2 years

Main exclusion criteria

Severe GERD despite meds
Large hiatal hernia
Previous bariatric surgery
Inflammatory bowel disease

Baseline characteristics

Average age 43 years
Female sex - 72%
Average weight - 273 lbs (124 kg)
Average BMI - 44
Type 2 DM - 25%

Randomized treatment groups

Group 1 (107 patients): Laparoscopic sleeve gastrectomy
Group 2 (110 patients): Laparoscopic Roux-en-Y gastric bypass (RYGB)
Treatment was unblinded

Primary outcome: Weight loss, defined as percentage excess BMI loss (100 × [baseline BMI − follow-up BMI]/[baseline BMI − 25]), over a 5-year period

Results

Outcome	Gastric sleeve	RYGB	Comparisons
Duration: 5 years
Weight loss	73 lbs (33 kg)	81 lbs (36.6 kg)	p=0.19
Percent weight loss	25%	28.6%	p=0.02
Primary outcome (excess BMI loss)	61%	68%	p=0.22
Post-op intervention	15.8%	22.1%	N/A
Overall mortality	0%	1.9%	N/A
Weight loss nadir was reached between years 1 and 2 in both groups In the gastric sleeve group, 9 patients underwent conversion to RYGB during follow-up due to GERD

RYGB with Silastic RIng vs Gastric Sleeve for Diabetes Remission at 5 Years, Diabetes Care (2022) [PubMed abstract]

The study enrolled 114 obese adults with types 2 diabetes in New Zealand

Main inclusion criteria

Age 20 - 55 years
Type 2 diabetes for ≥ 6 months
BMI 35 - 65 for ≥ 5 years

Main exclusion criteria

C-peptide < 350 pmol/L
Type 1 diabetes
Current smoker
Chronic pancreatitis

Baseline characteristics

Average age 46 years
Female sex - 52%
Average weight - 275 lbs (125 kg)
Average BMI - 42.8
Average A1C - 7.9%

Randomized treatment groups

Group 1 (56 patients): Silastic ring laparoscopic Roux-en-Y gastric bypass (SR-LRYGB)
Group 2 (58 patients): Laparoscopic sleeve gastrectomy (LSG)
Treatment was double-blinded
SR-LRYGB is gastric bypass with a silastic ring placed around the pouch just above its connection with the jejunum. The ring prevents the pouch from expanding and can increase the long-term success of the procedure.

Results

Outcome	SR-LRYGB	LSG	Comparisons
Duration: 5 years
Primary outcome	48%	31%	p=0.015
% weight loss	26.9%	16.3%	p<0.001
Body weight lost	73 lbs (33.3 kg)	46.4 lbs (21.1 kg)	p<0.05
Nadir body weight was reached at 12 months after SR-LRYGB and at 9 months after LSG, after which there was steady mean weight regain to 5 years The early (< 30 days post-op)) minor morbidity rate was 12.5% (N=7) for SR-LRYGB and 5.2% (N=3) for LSG (p=0.20), while early major morbidity rate was 3.6% (N=2) for SR-LRYGB and 8.6% (N=5) for LSG (p=0.44). Late (> 30 days post-op) minor and major complications were 19.6% (N=11) and 12.5% (N=7) after SR-LRYGB versus 12.1% (N=7) and 3.4% (N=2) after LSG (p=0.31 and p=0.09, respectively).

Findings: SR-LRYGB provided superior diabetes remission and weight loss compared with LSG at 5 years, with similar low risks of complications

Summary

In the two studies above, gastric bypass led to greater weight loss than gastric sleeve at 5 years. The difference was more pronounced in the SR-LRYGB study (26.9% vs 16.3%) than in the SM-BOSS study (28.6% vs 25%). The SR-LRYGB study was unique in that participants and researchers were blinded to the procedure that was performed. In both studies, gastric bypass had a slightly higher complication rate. Gastric sleeve was more effective in the SM-BOSS study (25% vs 16.3% weight loss), which took place at 4 bariatric centers in Switzerland; the SR-LRYGB study was a single-center study in New Zealand. Given these differences in demographics and design, it's difficult to make direct comparisons between the studies.

GASTRIC BANDING

Procedure

The gastric band is a silicone device that is placed around the top part of the stomach. The band restricts the size of the upper stomach so that the amount a person can eat is limited. The circumference of the band can be adjusted by injecting fluid through a subcutaneous port connected to the band.

Advantages

Less invasive than gastric sleeve and bypass
Patient can go home the same day
The band can be removed if needed
Lower risk of long-term nutritional deficiencies

Disadvantages

The band often requires adjusting, particularly during the first year
Less weight loss than other procedures
The band may move or slip
The band can erode through the stomach
High reoperation rate
May cause swallowing problems and enlargement of the esophagus [11]

ENDOSCOPIC SLEEVE GASTROPLASTY

Procedure

Endoscopic sleeve gastroplasty (ESG) is a bariatric procedure where an endoscope is advanced into the stomach, and a special device is used to suture part of the stomach lumen together, reducing its size. The intent is to achieve an effect similar to sleeve gastrectomy without the surgery. The procedure is performed under general anesthesia in the outpatient setting, allowing most patients to go home the same day.

Advantages

No invasive surgery
Lower cost than sleeve gastrectomy
No hospital stay

Disadvantages

Newer procedure with less long-term data
May require a "retightening" if response is lost or suboptimal

MERIT trial - Endoscopic Sleeve Gastroplasty vs Lifestyle Modification for Obesity, Lancet (2022) [PubMed abstract]

The MERIT trial enrolled 209 adults with a BMI of 30 - 40

Main inclusion criteria

Age 21 - 65 years
BMI of 30 - 40
Failed non-surgical weight loss methods

Main exclusion criteria

Inflammatory bowel disease
Gastric mass or polyps > 1 cm in size
Hiatal hernia w/ > 4 cm axial displacement
History of GI surgery
Diabetes requiring insulin

Baseline characteristics

Average age 46 years
Female - 86%
Average weight - 216 lbs (98 kg)
Average BMI - 35
Diabetes - 27%

Randomized treatment groups

Group 1 (77 patients): Endoscopic sleeve gastroplasty + lifestyle modification
Group 2 (110 patients): Lifestyle modification, including low-calorie diet plan and physical activity counseling
After 52 weeks, patients in the ESG group could receive retightening either on the basis of a suboptimal response to the primary intervention or at the discretion of the treating investigator
After 52 weeks, patients in the control group could crossover to ESG
All patients were followed for 104 weeks

Primary outcome: Percentage of excess weight loss (EWL) at 52 weeks, where EWL = weight loss / (actual body weight - body weight if BMI was 25) X 100.

Results

Outcome	ESG	Lifestyle	Comparisons
Duration: 52 weeks
Primary outcome (EWL)	49.2%	3.2%	p<0.0001
% weight loss (52 weeks)	13.6%	0.8%	p<0.0001
Body weight lost	29.5 lbs (13.4 kg)	1.8 lbs (0.8 kg)	N/A
In the ESG group, percent weight loss at 104 weeks was 11.4% After 52 weeks, 14 patients in the ESG group underwent retightening Adverse events in the ESG group included abdominal pain (15%), heartburn (8%), nausea (15%), and vomiting (15%); most resolved within 1 week. Three patients experienced procedure-related adverse events that required intervention, and 4% of patients required hospitalization for accommodative symptoms (e.g. nausea, vomiting).

Findings: ESG is a safe intervention that resulted in significant weight loss, maintained at 104 weeks, with important improvements in metabolic comorbidities. ESG should be considered as a synergistic weight loss intervention for patients with class 1 or class 2 obesity.

BILIOPANCREATIC DIVERSION WITH DUODENAL SWITCH (BPD/DS)

Procedure

A BPD/DS procedure starts with a sleeve gastrectomy. The duodenum is then separated from the stomach, and the ileum is cut approximately 250 cm from the cecum. The ileum is then brought up and connected to the stomach. The duodenum and the remaining small intestine are connected to the ileum about 100 cm from the cecum.

BPD/DS illustration

Advantages

Causes the most weight loss of all the procedures
Affects intestinal hormones and reduces hunger
Very effective at treating type 2 diabetes

Disadvantages

More complex procedure with higher complication rate
Carries greatest risk of long-term vitamin and mineral deficiencies
May worsen or cause new-onset reflux and heartburn
Bowel movements may become looser and more frequent [11]

INTRAGASTRIC BALLOON

Procedure

The intragastric balloon is a device placed in the stomach through endoscopy. The device is then filled with normal saline causing it to expand to the size of a grapefruit and occupy space in the stomach. Theoretically, this slows digestion and causes a sensation of fullness and satiety that leads to weight loss. The balloon is left in place for 6 months, at which time it is deflated and removed endoscopically. In the U.S., only the Orbera® balloon system is currently available. Another balloon system called ReShape® was approved in 2015, but in 2018, the manufacturer of Orbera® bought ReShape® and discontinued it. See the Orbera website for more.

Advantages

Balloon is placed endoscopically during an outpatient procedure that lasts about 20 minutes
Balloon can easily be removed

Disadvantages

Less weight loss than other procedures
Balloon must be removed after 6 months, and weight is often gained back
Must take acid-suppressing medications to prevent stomach ulcers
High rate of nausea and vomiting which may require early removal

Orbera plus Lifestyle Intervention vs Lifestyle Intervention for Obesity, International Journal of Obesity (2017) [PubMed abstract]

The trial enrolled 255 obese adults with a BMI of 30 - 40

Main inclusion criteria

BMI 30 - 40
Obesity for at least 2 years
Failed conservative weight loss (e.g. diet, exercise)

Main exclusion criteria

History of GI surgery (except appy or choly)
History of GI obstruction
GI motility disorder
Significant hiatal hernia
Positive H pylori at screening
Inflammatory bowel disease

Baseline characteristics

Average age 39 years
Female sex - 90%
Average weight - 215 pounds
Average BMI - 35

Randomized treatment groups

Group 1 (125 patients) - Orbera intragastric balloon for 6 months + Lifestyle intervention
Group 2 (130 patients) - Lifestyle intervention
The 12-month lifestyle intervention program incorporated the following elements: a low calorie (1000–1500 calories per day) diet, daily food and exercise diary, encouragement to exercise and emphasis on behavioral change during a total of 21 visits (9 visits in months 1–6, 12 visits in months 7–12)

Primary outcome: Difference in the average percent excess weight loss (%EWL) between groups at 9 months and difference in patients with ≥ 15% EWL at 9 months. Percent excess weight loss = Weight loss/(actual body weight - body weight if BMI was 25) X 100.

Results

Outcome	Orbera + Lifestyle	Lifestyle	Comparisons
Duration: 12 months
Weight loss (6 months)	21.8 lbs (9.9 kg) \| 10.2%	7 lbs (3.2 kg) \| 3.3%	p<0.001
Weight loss (9 months)	19.4 lbs (8.8 kg) \| 9.1%	7 lbs (3.2 kg) \| 3.4%	p<0.001
Weight loss (12 months)	16.3 lbs (7.4 kg) \| 7.6%	6.8 lbs (3.1 kg) \| 2.9%	p<0.001
Primary outcome (%EWL at 9 months)	26.5%	9.7%	N/A
Primary outcome (≥15% EWL at 9 months)	Orbera 45.6% more than control		p<0.001
The study had a run-in phase where an additional 35 patients received the Orbera device. Of the total number of patients who received the device (N=160), 30 (18.8%) had it removed early due to side effects or intolerance. Side effects in the Orbera group included the following: nausea (87%), vomiting (76%), abdominal pain (58%), GERD (30%), burping (24%), dyspepsia (21%), constipation (20%)

Findings: Intragastric balloon achieved greater short-term weight loss at 3 and 6 months postballoon removal than lifestyle intervention alone. Adverse gastrointestinal events were common.

AGA 2021 recommendations

The AGA suggests the use of the intragastric balloon (IGB) in individuals with obesity seeking a weight-loss intervention who have failed a trial of conventional weight-loss strategies
Individuals who receive an IGB should also receive moderate- to high-intensity concomitant lifestyle modification interventions
Patients with an IGB should receive prophylactic therapy with a proton pump inhibitor to prevent stomach ulcers and bleeding
Patients who receive an IGB should receive an antiemetic regimen for 2 weeks after placement
Perioperative laboratory screening for nutritional deficiencies is not recommended
Daily supplementation with 1 - 2 adult multivitamins is recommended during placement [12]

Summary

In the trial above, the Orbera intragastric balloon improved weight loss by about 7% compared to control while it was in place. After removal, patients gained back weight, and at 6 months post-removal, the difference in weight loss was only 4.6%. The weight loss benefit would likely disappear with longer follow-up. Side effects were common, and 19% of patients who received the device had it removed before 6 months.
In 2018, the FDA issued a safety alert stating that since 2016, a total of 12 patient deaths worldwide have been reported involving the Orbera Intragastric Balloon System and the ReShape Integrated Dual Balloon System

GASTRIC ASPIRATION DEVICE

Overview

In 2016, the FDA approved the AspireAssist gastric aspiration device. AspireAssist is a gastrostomy tube that is implanted through the abdominal wall and into the stomach. The device has a port on the skin that connects to the gastrostomy tube. Twenty to thirty minutes after consuming a meal, the patient connects an external drainage device to the skin port and drains the gastric contents into the toilet. This typically removes 30% of consumed calories.
In February 2022, the company that makes AspireAssist announced that they were discontinuing it effective April 8, 2022 (see Aspire Bariatrics for more).

PATHWAY trial - AspireAssist vs Control for Weight Loss (2015)

The PATHWAY trial enrolled 171 obese patients with a BMI of 35 - 55

Main inclusion criteria

BMI 35 - 55
21 - 65 years old
Failed at least 3 months of conservative weight loss measures
No weight change > 3% within 3 months

Main exclusion criteria

Previous upper GI surgery or pathology that would interfere with gastrostomy tube
Refractory gastric ulcers
Inflammatory bowel disease
Diabetes treated with insulin or sulfonylurea
HgA1C > 9.5%
Significant pulmonary or cardiovascular disease
Osteoporosis
Taking medications that cause weight loss within 3 months

Baseline characteristics

Average age 44 years
Average BMI - 41
Average weight - 251 lbs (114 kg)
Female sex - 87%

Randomized treatment groups

Group 1 (111 patients) - Implantation of AspireAssist device
Group 2 (60 patients) - No implantation (control group)
All patients received diet and exercise counseling once a month for 12 months

Primary outcome: 1. Percent excess weight loss (%EWL) at 52 weeks 2. Percent of patients who lost ≥ 25% of EWL at 52 weeks. Percent excess weight loss = Weight loss/(actual body weight - body weight if BMI was 25) X 100.

Results

Outcome	AspireAssist	Control	Comparisons
Duration: 52 weeks
Percent excess weight loss	32%	10%	diff 21.7%, 95%CI [15% to 28%], p=0.0083
Percent losing ≥ 25% of EWL	57%	22%	diff 34%, p<0.05
Percent of total body weight lost	12.1%	3.6%	diff 8.6%, 95%CI [6.2% to 10.9%]
Average weight loss	30 lbs	9 lbs	diff 21.6 lbs, 95%CI [16 to 27]
Study discontinuations	26%	48%	N/A
Adverse events in the AspireAssist device group occurring in ≥ 5% of subjects: Peristomal granulation tissue (41%), abdominal pain ≤ 4 weeks after placement (38%), nausea/vomiting (18%), peristomal irritation (17%), intermittent abdominal discomfort (16%), peristomal infection (14%), abdominal pain > 4 weeks after placement (8%), dyspepsia (6%), peristomal inflammation (5%) One participant had to have his tube replaced and one participant developed peritonitis after the procedure [39]

Summary

In the PATHWAY trial, the AspireAssist device caused significant weight loss compared to control. In practical terms, a patient weighing 251 pounds can expect an additional 22 lbs of weight loss over 52 weeks with the device. The device is invasive and requires daily hygiene and operational maintenance.
The manufacturer discontinued the device in 2022

VAGAL NERVE BLOCKADE

Overview

In 2015, the FDA approved an implantable device called the Maestro Rechargeable System to treat obesity. The device is implanted in the abdomen, where it sends intermittent electrical pulses to the vagus nerve at the gastroesophageal junction. The vagus nerve is involved in regulating stomach emptying and signaling to the brain that the stomach feels empty or full. The electrical impulses block nerve activity between the brain and stomach. The mechanism by which this causes weight loss is unknown. The device can be charged and adjusted through an external controller. The device was approved based on results from the ReCharge Study presented below.
The company that makes the system, Enteromedics, changed its name to ReShape Lifesciences in 2017. The ReShape website does not mention the Maestro system, so it appears to no longer be available. The FDA website says that it is no longer marketed as of September 2018 (see FDA website).

ReCharge Study - Vagal Nerve Blockade vs Sham Device for Weight Loss, JAMA (2014) [PubMed abstract]

The ReCharge study enrolled 239 obese patients

Main inclusion criteria

BMI 40 - 45, or BMI 35 - 39 with ≥ 1 obesity-related condition (hypertension, diabetes, dyslipidemia, sleep apnea, cardiomyopathy)

Main exclusion criteria

History of bariatric surgery
Hiatal hernia (> 5 cm)
History of inflammatory bowel disease
Medications for weight loss within 3 months
Chronic treatment with narcotic analgesics

Baseline characteristics

Average age 47 years
Female sex - 84%
Average BMI - 41
Average weight - 251 lbs (114 kg)

Patients were randomized in a 2:1 ratio to one of two groups:

Group 1 (162 patients) - Vagal nerve blockade device + weight management program
Group 2 (77 patients) - Sham device + weight management program
Patients in Group 2 had the device implanted, but it was not able to function
In Group 1, the device delivered a charge for at least 12 hours a day. The charge was increased via a protocol to a desired charge, depending on patient tolerance. The device was recharged at least twice a week for 30 - 90 minute intervals.

Primary outcome: Coprimary efficacy objectives were to determine whether the vagal nerve block was superior in mean percentage excess weight loss to sham by a 10-point margin with at least 55% of patients in the vagal block group achieving a 20% loss and 45% achieving a 25% loss. Percent excess weight loss = Weight loss/(actual body weight - body weight if BMI was 25) X 100

Results

Outcome	Vagal nerve blockade	Sham	Comparisons
Duration: 12 months
Percent excess weight loss	24.4%	15.9%	diff 8.5%, 95%CI [3.1 - 13.9]
Percent of actual body weight lost	9.2%	6%	diff 3.2%, 95%CI [1.1 - 5.2]
Heartburn	23%	4%	N/A
Pain, other	23%	0%	N/A
Abdominal pain	12%	3%	N/A
Dysphagia	8%	0%	N/A
Burping	8%	0%	N/A
Nausea	7%	1%	N/A
Chest pain	6%	3%	N/A
The prespecified primary objective was not met because the device did not achieve a 10% greater loss of excess weight Three patients in the vagal nerve blockade group required another surgical procedure because of device issues

Findings: Among patients with morbid obesity, the use of vagal nerve block therapy compared with a sham control device did not meet either of the prespecified coprimary efficacy objectives, although weight loss in the vagal block group was statistically greater than in the sham device group. The treatment was well tolerated, having met the primary safety objective.

Summary

In the ReCharge study, the vagal nerve stimulator was slightly better than a sham procedure for weight loss, but it did not meet its prespecified goal. In practical terms, someone with a bodyweight of 251 pounds and a BMI of 41 can expect to lose an average of 8 additional pounds after one year with the stimulator. Patients with the device are also at greater risk for significant side effects.
The system appears to no longer be available

GLP DRUGS FOR WEIGHT REGAIN

For patients who regain weight after surgery, options are limited. The highly-effective GLP weight-loss drugs (e.g. semaglutide, liraglutide) are an emerging option, but clinical data on their use in this patient population is sparse. The studies below evaluated GLP drugs in bariatric surgery patients who regained weight after their procedure; the first one is a randomized controlled trial, and the others are observational.

BIBLIOGRAPHY

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11 - ASMBS website
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13 - PMID 35908555 Endoscopic sleeve gastroplasty for treatment of class 1 and 2 obesity (MERIT): a prospective, multicentre, randomised trial, Lancet (2022)

WEIGHT LOSS PROCEDURES