Gastric sleeve surgery and gastric bypass surgery are both weight loss procedures. However, they differ in how they lead to weight loss and their effects on the digestive system.

Gastric sleeve and gastric bypass surgery are the two most common types of bariatric surgery. Both surgeries aim to reduce the size of a person’s stomach and limit the amount of food they can eat. This article examines how they work, their benefits and risks, and how they affect recovery and lifestyle.

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Gastric sleeveGastric bypass
Approachsurgeons remove part of the stomachsurgeons bypass part of the stomach and intestines
Complexityrelatively simplemore technically complicated
Also known assleeve gastrectomy or vertical sleeve gastrectomyRoux-en-Y
Areas impactedstomach onlystomach and small intestine
Risks or complicationsrisk of some complicationsrisk of more serious complications
Surgical methodlaparoscopic or openlaparoscopic or open

Gastric sleeve surgery involves permanently removing about 80% of a person’s stomach, leaving a small banana-shaped pouch that can hold about a cup of food.

This surgery reduces the appetite by lowering the production of ghrelin, the hormone that stimulates hunger. It also limits the amount of calories someone can consume by making them feel full faster and for longer.

Read more about gastric sleeve surgery.

Gastric bypass surgery involves creating a small pouch at the top of the stomach and connecting it directly to the middle part of the small intestine. This then bypasses the rest of the stomach and the first part of the small intestine.

This surgery reduces a person’s appetite by making them feel full with less food and reduces the absorption of calories and nutrients in the intestines. It is also called Roux-en-Y gastric bypass surgery.

Read more about gastric bypass surgery.

Approximately 90% of individuals who undergo bariatric surgery achieve a long-term weight loss of at least 50% of their excess body weight. One clinical trial noted no statistical difference in weight loss between the two types of surgery.

The following sections describe the benefits of both surgeries.

Gastric sleeve surgery benefits

Some of the reasons a person may choose this surgery include:

  • Simplicity of procedure: The gastric sleeve procedure is less complex than gastric bypass, so it can lead to shorter operating times and potentially fewer complications related to surgical complexity.
  • No rerouting of intestines: Unlike gastric bypass, sleeve surgery does not involve rerouting the intestines, which means that the typical absorption of nutrients remains largely intact. This can reduce the risk of certain nutritional deficiencies.

Gastric bypass surgery benefits

Benefits of this surgery include:

  • Rapid initial weight loss: People often experience rapid weight loss in the first 6 months after gastric bypass, which can be particularly motivating.
  • Reduction in hunger hormones: Gastric bypass surgery can reduce the production of the hunger hormone ghrelin, which can help people control their appetite more effectively.

Benefits that both procedures share

The benefits of both types of bariatric surgery include:

  • Long-term sustained weight loss: Both gastric sleeve and gastric bypass can result in long-term weight loss, especially in combination with lifestyle changes, healthy eating habits, and regular physical activity.
  • Improved quality of life: People often report an enhanced quality of life after weight loss surgery, including increased mobility, reduced pain, improved self-esteem, and a higher overall sense of well-being.
  • Resolution of comorbidities: Many individuals experience significant improvements or remission of obesity-related health conditions such as type 2 diabetes, hypertension, sleep apnea, and joint pain.
  • Reduced mortality: Weight loss surgery often has links to reduced overall mortality rates among individuals with obesity, particularly those with severe obesity.

Most people typically spend 1–2 days in the hospital after bariatric surgery. The exact duration may vary depending on individual factors and the surgical team’s recommendations.

People need to follow their healthcare team’s recommendations about food intake. Generally, it will involve the following plan:

  • week 1–3: liquid diet — no caffeinated, carbonated, or alcoholic drinks
  • week 4–5: pureed diet
  • week 6–9: soft and moist solids
  • week 10: very small amounts of regular food

Read about how to eat after gastric bypass surgery.

Both procedures are generally safe and effective for weight loss, but specific risks and complications can vary from person to person.

Both types of bariatric surgery can cause hemorrhage, which refers to excessive bleeding. Other risks both surgeries share include:

The following sections describe the risks and complications of both surgeries.

Gastric sleeve surgery complications

Some risks and complications of gastric sleeve surgery include:

  • Gastroesophageal reflux disease (GERD): Some people may experience worsening or new-onset GERD symptoms after a sleeve gastrectomy gastric bypass surgery.
  • Stricture: Narrowing of the sleeve may occur, causing difficulty in swallowing and requiring additional interventions.

Learn about the connection between GERD and gastric bypass surgery.

Gastric bypass surgery

Some risks and complications of gastric bypass surgery include:

  • Marginal ulcers: Ulcers can develop where the small intestine connects to the pouch. These ulcers may cause pain, bleeding, or discomfort.
  • Internal hernia: There is a risk of developing internal hernias in the small bowel mesentery, which can cause bowel obstructions and require surgery.
  • Gallstones: Rapid weight loss following gastric bypass can increase the risk of developing gallstones.

Gastric sleeve and gastric bypass surgery both require lifelong changes in a person’s diet and lifestyle to maintain their weight loss and health.

People also make the following lifestyle changes:

  • eat smaller portions of nutritious foods,
  • avoid high fat, high sugar, and high calorie foods
  • drink plenty of water
  • take vitamin and mineral supplements
  • exercise regularly
  • have follow-up appointments with their doctor

According to the American Society for Metabolic and Bariatric Surgery (ASMBS), bariatric surgery costs between $17,000 and $26,000.

Insurance may cover this cost if the procedure is medically necessary, depending on the specifics of a person’s insurance coverage.

Read about Medicare and weight loss surgery.

The choice between gastric sleeve and gastric bypass surgery depends on individual factors, including a person’s health status and preferences and discussions with a medical team.

Both surgeries lead to long-term weight loss in most people but have associated risks.

Individuals need to consult a healthcare professional to determine the most appropriate option.