What is the difference between gastric sleeve and gastric bypass surgery for an adult patient with a body mass index (BMI) of 40 or higher, or a BMI of 35 or higher with at least one obesity-related condition, such as type 2 diabetes or hypertension?

Gastric Sleeve vs Gastric Bypass: Key Differences

Both laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) are effective bariatric procedures, but gastric bypass achieves superior weight loss (approximately 30% total body weight loss at 12 months vs 25% for sleeve gastrectomy) and better resolution of metabolic comorbidities, particularly type 2 diabetes and dyslipidemia, though it carries a higher complication rate. 1

Weight Loss Outcomes

Short to Medium-Term Results (1-3 Years)

• Gastric bypass produces greater weight loss than sleeve gastrectomy at 2-3 years, with moderate strength of evidence 1
• Expected 12-month weight loss: approximately 30% total body weight after RYGB vs 25% after LSG 1
• At 1 year, percentage excess weight loss (%EWL) is significantly higher with gastric bypass: 66.2% vs 57.3% for sleeve gastrectomy 2, 3

Long-Term Results (5+ Years)

• At 5 years, gastric bypass maintains superior weight loss with 57% excess weight loss compared to 49% for sleeve gastrectomy, though this difference did not meet prespecified equivalence criteria 4
• Long-term studies show gastric bypass achieves 65.7% excess weight loss vs 45.0% for gastric band procedures, with sustained results beyond 5 years 5
• Both procedures show weight regain at 4 years, with BMI returning to obese range (30.67 kg/m² for SG vs 30.32 kg/m² for RYGB), though RYGB maintains slightly better outcomes 6

Resolution of Metabolic Comorbidities

Type 2 Diabetes

• Gastric bypass achieves superior diabetes remission: 66.7% remission rate (defined as HbA1c <6.5% without medication) vs 28.6% for gastric band 5
• At 5 years, complete or partial diabetes remission occurs in 45% after RYGB vs 37% after LSG, though this difference was not statistically significant 4
• Type 2 diabetes remission occurs with increasing frequency: gastric band < gastric bypass < biliopancreatic diversion 1

Hypertension

• Gastric bypass produces more frequent hypertension resolution than gastric band procedures 1
• Remission rates (BP <140/90 mmHg without medication): 38.2% for RYGB vs 17.4% for gastric band 5
• At 5 years, 51% discontinued hypertension medications after RYGB vs 29% after LSG (p=0.02) 4

Dyslipidemia

• Gastric bypass achieves significantly better dyslipidemia resolution than sleeve gastrectomy 2, 4
• Remission rates: 60.4% for RYGB vs 22.7% for gastric band 5
• At 5 years, 60% discontinued dyslipidemia medications after RYGB vs 47% after LSG (p=0.15) 4
• The prevalence of dyslipidemia is consistently lower after gastric bypass compared to other procedures 1

Complication Profiles

Perioperative Complications (≤30 Days)

• Gastric bypass has higher early complication rates: 4-5% major adverse outcomes including 0.2% mortality, 0.4% venous thromboembolism, and 3-5% reoperation rate 1
• Sleeve gastrectomy has lower perioperative complications: 3.0% vs 9.3% for gastric bypass in super-obese patients 3
• Bleeding and wound infection are more common with RYGB than LSG 2
• Mean operation time is shorter for sleeve gastrectomy: 81.7 minutes vs 112.1 minutes for gastric bypass 3
• Hospital stay is shorter after sleeve gastrectomy: 4.5 days vs 7.2 days for gastric bypass 3

Late Complications (>30 Days)

• Anastomotic/staple line leaks: 1-7% for LSG vs 0.6-4.4% for RYGB 1
• Stenosis: 1-9% for LSG vs 8-19% for RYGB 1
• Internal hernia and marginal ulceration: 2.5-5% specific to RYGB 1
• Intestinal obstruction occurs more frequently as a late complication after RYGB 2
• Overall 5-year morbidity: 19% for sleeve gastrectomy vs 26% for gastric bypass (p=0.19) 4

Nutritional Considerations

Micronutrient Deficiencies

• Both procedures require lifelong supplementation, but RYGB typically requires more intensive monitoring 1
• Essential supplements include: thiamin, vitamin B12, folate, iron, vitamin D, calcium, vitamin A, vitamin E, vitamin K, zinc, and copper 1, 7
• Pre- and post-surgical screening and supplementation is mandatory for both procedures 1

Protein Requirements

• Daily protein intake of 60-80 g/day or 1.0-1.5 g/kg ideal body weight is necessary to preserve lean body mass after both procedures 7

Procedural Selection Algorithm

Choose Gastric Bypass When:

• Maximum weight loss is the priority (expected 30% total body weight loss at 12 months) 1
• Severe type 2 diabetes requiring best chance of remission (66.7% remission rate) 5
• Severe dyslipidemia requiring aggressive metabolic improvement 2, 4
• Patient can tolerate higher perioperative risk and longer operative time 3
• Patient commits to more intensive nutritional monitoring 1

Choose Sleeve Gastrectomy When:

• Lower perioperative risk is prioritized (3.0% vs 9.3% complication rate) 3
• Patient prefers shorter operative time and hospital stay 3
• Contraindications to gastric bypass exist (e.g., hiatal hernia, gastric ulcers) 1
• Patient has less severe metabolic disease where 25% weight loss is acceptable 1
• Patient prefers organ-sparing procedure with potentially reversible anatomy 1

Current Eligibility Criteria

BMI Thresholds

• BMI ≥40 regardless of comorbidities 1, 8, 9
• BMI ≥35 with at least one severe obesity-related comorbidity (type 2 diabetes, hypertension, hyperlipidemia, obstructive sleep apnea) 1, 8, 9
• Recent guidelines now recommend BMI ≥30-34.9 with concurrent metabolic disease 1, 9
• Lower thresholds (BMI ≥25) should be applied to Asian populations 1, 7, 9

Preoperative Requirements

• Trial of nonsurgical therapy recommended for BMI <35 prior to referral 1
• Presurgical nutrition evaluation to identify deficiencies and establish baseline 1, 7, 9
• Mental health evaluation to assess psychological readiness 1, 7, 9

Common Pitfalls to Avoid

• Do not delay surgery unduly in patients with treatment-resistant hypertension and multiple severe comorbidities despite preoperative optimization requirements 8
• Refer to high-volume centers with experienced bariatric surgeons to optimize outcomes and minimize mortality (0.1-0.3% at experienced centers) 8
• Ensure patient understanding that long-term success requires continued participation in comprehensive lifestyle programs, as 20-30% may experience suboptimal response or weight regain 9
• Arrange close follow-up every 4-6 weeks initially to support lifestyle changes and detect complications early 1, 7
• Do not assume equivalence: while both procedures are effective, gastric bypass consistently demonstrates superior metabolic outcomes despite higher complication rates 4, 5