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Gastric bypass vs. gastric sleeve

Gastric Bypass vs. Gastric Sleeve

Gastric bypass and gastric sleeve (also called sleeve gastrectomy) are types of bariatric surgery that are recommended for patients with a weight loss goal of 25% of their initial weight or more. As you explore what type of surgery is best for your individual needs, it’s helpful to compare gastric bypass vs. gastric sleeve to fully understand your options. 

What is a Gastric Bypass?


During Roux-en-Y gastric bypass surgery, the surgeon makes the stomach smaller and reroutes the small intestine. The procedure creates a new stomach pouch about the size of an egg, using only about 5% of the existing stomach. The surgeon then attaches a section of the small intestine directly to the pouch, which allows food to bypass a portion of the small intestine that absorbs calories and nutrients. 

This smaller stomach pouch limits the amount of food you can eat, helping you to feel full faster and eat less. Rerouting the small intestine also causes the body to absorb fewer calories, contributing to weight loss. 

Expected Weight Loss

Gastric bypass patients typically lose about 35% of their initial weight in the first year after surgery. 

Hospital Stay and Recovery Time

Gastric bypass surgery takes about 2 hours to perform. It requires 1-2 days of hospital stay and a 3-week recovery period. To reach their weight loss goals, patients follow specific diet and exercise guidelines provided by the bariatric team. Required diet changes focus on increasing protein intake and taking a daily multivitamin with iron and calcium supplements. 

Potential Complications

Potential complications of gastric bypass include infections, blood clots, leakage (when digestive fluids go into the abdominal cavity or surround areas) and a condition called “dumping syndrome,” which can occur from eating high-fat, high-sugar foods. In some cases, dumping can cause vomiting, nausea, diarrhea, weakness, and sweating. The chance of a significant complication early after gastric bypass is less than 5%. 

What is a Gastric Sleeve?


During gastric sleeve surgery, the surgeon removes about 85% of the stomach, leaving a smaller sleeve-shaped stomach about the size of a banana. This procedure significantly reduces the stomach’s volume without rerouting the intestines, a key difference from a gastric bypass. 

Expected Weight Loss

Patients typically lose 30% of their initial weight after a gastric sleeve; most of it is lost during the first year after surgery.

Hospital Stay and Recovery Time

Gastric sleeve surgery takes approximately one hour. It requires 1-2 days in the hospital and a 3-week recovery period. To reach their weight loss goals, patients must follow specific diet and exercise guidelines provided by the bariatric team. Required diet changes include smaller meals focusing on adequate protein intake. 

Potential Complications

Potential complications of gastric sleeve surgery include leakage and stricture, which is the narrowing of the gastrointestinal tract. Some patients experience worsening or new heartburn after sleeve gastrectomy. It may be a standalone bariatric procedure or be performed first in a two-part treatment for patients with a BMI of 60 or higher. The second part of the treatment is a duodenal switch (described below) or a gastric bypass.

Who Should Consider Gastric Bypass or Gastric Sleeve?

Gastric bypass and gastric sleeve may be appropriate for patients with a weight loss goal of 25% of their initial weight or more. These are among the safest, most effective surgical options to lose weight and end symptoms of health issues, including:

  • Types 2 diabetes
  • Gastric reflux
  • Sleep apnea
  • Joint pain
  • High blood pressure 

Your bariatric surgeon will work closely with you to develop a comprehensive, individualized plan, including setting post-surgery guidelines promoting weight loss success. 

Another Bariatric Procedure: Duodenal Switch

The duodenal switch is a procedure generally reserved as an option for patients with even more excess weight, and a BMI of 50 or over. This procedure is a combination of gastric sleeve and intestinal rerouting to the bottom of the sleeve. During a duodenal switch, 85% of the stomach is removed (creating a sleeve gastrectomy) and a larger section of the small intestine is bypassed than with the gastric bypass. 

This surgery is sometimes performed in two stages: stage one involves gastric sleeve surgery and stage two involves rerouting the small intestine. Patients lose on average 40% of their initial weight. This procedure often leads to the strongest improvement in type 2 diabetes. 

The duodenal switch has more potential than other bariatric surgeries to cause vitamin, mineral, and protein deficiencies. That’s why adherence to dietary and vitamin supplementation guidelines is critical to avoid serious nutritional complications over time. Strict compliance with follow-up visits and post-operative recommendations is most important after a duodenal switch.

Stony Brook Medicine’s Bariatric and Metabolic Weight Loss Center is a credentialed, multidisciplinary team that offers medical management, advanced nutrition and exercise plans, counseling, behavior modification, and group support as part of every surgical weight loss program.  

  • Konstantinos Spaniolas, MD
    Division chief
    Professor of Surgery
    Director, Bariatric and Metabolic Weight Loss Center
    Director, SOAR Collaborative

    Bariatric surgery is a life-changing process for patients. My involvement in the Stony Brook Bariatric and Metabolic Weight Loss Center affords me the opportunity to work on a well-coordinated multidisciplinary team and provide cutting-edge bariatric care. Furthermore, I enjoy doing health services and outcomes research, primarily targeting bariatric surgery in high-risk populations.

This article is intended to be general and/or educational in nature. Always consult your healthcare professional for help, diagnosis, guidance and treatment.