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Gastric Sleeve vs. Gastric Bypass

Gastric Sleeve vs. Gastric Bypass

There are many types of weight-loss surgery, known collectively as bariatric surgery. Bariatric procedures alter the digestive system to induce weight loss, which can help patients decrease risks associated with overweight and obesity. This article aims to teach you what you need to know about gastric sleeve vs. gastric bypass,two of the most common types of bariatric surgery in the United States.

There are several things to consider when deciding which metabolic surgery is right for you. Your starting weight and your metabolic disease profile may have an impact on what operation works better for you. For example, if you have severe heartburn issues and diabetes, gastric bypass may be a better choice.

Gastric sleeve surgery is completed in approximately 1 hour on average. Gastric Bypass takes 2-3 hours on average.

Gastric Sleeve

The sleeve gastrectomy, also called vertical sleeve gastrectomy or VSG, is a bariatric procedure that essentially decreases the size of the stomach to induce metabolic changes. There are a few ways in which a sleeve results in weight loss.

During a gastric sleeve operation a surgeon removes most of the stomach, leaving a small sleeve-shaped section that is closed with staples. This results in a reduced amount of food that can fit in the smaller, new stomach. One effect of this surgery is that patients feel full sooner and are able to eat less food at one time.

The second way a sleeve gastrectomy induces weight loss is through a change in hormones. By taking out part of the stomach, gut hormones are changed to influence metabolism. These hormones have an impact on hunger, feelings of fullness, and blood sugar control.

This type of surgery generally cannot be reversed because a portion of the stomach is permanently removed.

Both types of surgery can help patients live a more active, healthy lifestyle.

Roux-en-Y Gastric Bypass

The Roux-en-Y Gastric Bypass is often referred to as “gastric bypass.” There are gastric restriction and malabsorption that result from this procedure.

There are two parts to this procedure, both of which are done in the same operation. First, surgeons create a small stomach pouch that is approximately 1 to 2 ounces. The second stage of the procedure involves rerouting of the intestines. This part of the procedure causes food and digestive enzymes to meet further down in the digestive tract.

Gastric bypass leads to weight loss by a few different mechanisms. First, the new stomach pouch is much smaller and allows for only small amounts of food at one time. Second, there is less digestion of food by the small pouch and rerouted intestines. Fewer calories and nutrients are absorbed. Lastly, the alteration of anatomy induces hormonal changes in the gut that are involved in satiety, hunger, and blood sugar control.

Researching the pros and cons of each type of surgery is a great way to be prepared for your bariatric consultation.

Benefits and Risks

Overall, studies comparing gastric bypass vs. gastric sleeve have found very similar health improvement for a variety of conditions including diabetes, hypertension, sleep apnea, and most other obesity-related health problems. However, there are some key differences to take into account.

Advantages of gastric sleeve:

  • Estimated average weight loss is approximately 60-70%of excess body weight
  • No rerouting of intestines
  • No reconnections of intestines, no risk for marginal ulcers
  • Less concern for vitamin and mineral deficiencies

Disadvantages of gastric sleeve:

  • Not as effective in super obesity
  • Possibility for gastric reflux

Advantages of gastric bypass:

  • Estimated average weight loss is approximately 70-80% of excess body weight
  • May resolve refractory GERD
  • May resolve refractory diabetes type 2 better than sleeve

Disadvantages of gastric bypass:

  • Must be diligent about vitamin and mineral regimen
  • More likely to experience dumping syndrome
  • More likely to experience marginal ulcers and internal hernias
Your doctor will review a comprehensive health history to determine which procedure will best benefit each unique patient.

Take Home Message

When deciding which surgery is right for you, it’s important to have complete awareness of the pros, cons, and indications for each type. In summary, both types of metabolic surgery induce weight loss either by restricting the amount of food the stomach can hold or by causing malabsorption of nutrients, or a combination of both. Both procedures also influence hormones and cause shifts in perceived hunger and fullness.

The bottom line: you should work with your surgeon to figure out which is the best surgery for you and your unique medical history.

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Morgyn Clair, MS, RDN


Morgyn is an RD specializing in weight management and surgical weight loss. She has a master's in clinical nutrition and dietetics, and currently works as a clinical dietitian in a physician’s office.

Gintas Antanavicius, MD, FACS, FASMBS


Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.