• Jacinta King

Sleeve vs Bypass

Updated: Jul 8, 2020

The two most common weight loss surgery procedures performed in Australia are the Sleeve Gastrectomy and the Gastric Bypass. There are two main types of Gastric Bypass procedures: the Roux-en-Y and the Single Loop (also referred to as the 'Mini Bypass' / 'One Anastomosis Bypass' / 'Omega Loop Bypass').


According to the Australian Bariatric Surgery Registry, 70% of weight loss surgery procedures performed in Australia in 2019 were Sleeve Gastrectomy's and 19% were Gastric Bypass's.


There are many different factors which go into determining which procedure will be best for you including:

  • Your current weight and weight history

  • Your medical and surgical history

  • History of previous weight loss surgery

  • Desire for future pregnancies


It is important to have an open and honest conversation with your surgeon in order to come to the best decision for you.


This article summarises some of the key differences between each procedure.


Sleeve Gastrectomy


Source: https://www.tijuanabariatrics.com/blog/2015/05/16/gastric-sleeve-and-anemia-what-158117


The Sleeve Gastrectomy is a procedure were approximately 80% of the stomach is removed creating a 'smaller' stomach which is commonly referred to as a pouch. The old part of the stomach is completely removed from the body. This is a non-reversible procedure. The remainder of your anatomy says in tact and the pathway of food through your body is practically the same.


The Sleeve is often referred to as a restrictive procedure as its primary function is to restrict the amount of food you can fit in. This makes you feel satisfied on a much smaller amount of food. The portion of the stomach that is removed is also the part that secretes the most of your hunger hormone called ghrelin. By removing this part of the stomach, you get a reduced production of ghrelin which further assists with reducing appetite and increasing satiety with a smaller amount of food. Over time you do see a return of this hormone, however levels are still often lower than pre surgery.


Following a Sleeve, some patients can develop a lactose intolerance and slower bowel motions.


Long term you can expect to fit in a portion size of approximately 1 metric cup equivalent of food in one sitting.


The average total body weight loss for those undergoing a Sleeve is 20-30%.


Gastric Bypass



Source: https://www.indiamart.com/company/8406735/services.html


The Roux-en-Y Gastric Bypass procedure is where a new stomach is created separate from your original stomach. Unlike the Sleeve, the original part of your stomach stays in the body - it is not removed. This allows for continual use of stomach juices (green arrows) to help with the digestion and breakdown of food. This new stomach then has the middle part of your intestine attached to it. This means that food (red arrows) exiting your stomach now bypasses the first part of the intestine and goes straight into the middle part - this is where the name Bypass comes from. This causes food to not be as well absorbed. Therefore, unlike the Sleeve which mainly works in one way (restricting the amount of food that comes in), the Bypass works in two ways:


  1. Restricts the amount of food that comes in with the creation of a new smaller stomach pouch.

  2. Bypasses the usual first step of digestion in the first part of the intestine and enters straight in the middle part of the intestine, inducing malabsorption of food which assists with further weight loss.


Due to these two mechanisms of action, the Bypass is often referred to as the more 'aggressive' weight loss procedure. It is important to note however, that bypassing part of the intestine not only means that less food is absorbed, but also less vitamins and minerals.


The Roux-en-Y Bypass has two new connection sites - the bottom of the stomach and the intestine. These connection sites are referred to anastomoses. The main difference with the Mini Bypass is that it only has one connection site, or one anastomosis, at the bottom of the stomach. This is attractive to many surgeons as it is a less surgically invasive procedure.


Following a Gastric Bypass some patients can develop a lactose intolerance and looser bowel motions. Gastric Bypass patients are also at higher risk of developing Dumping Syndrome and Reactive Hypoclycaemia. Both of these conditions can be largely dietary managed through individualised advice from your Dietitian.


Long term you can expect to fit in a portion size of approximately 1 metric cup equivalent of food in one sitting.


The average total body weight loss for those undergoing a Roux-en-Y Gastric Bypass is 23-25%, and 32-38% for those undergoing a Mini Gastric Bypass.


Key Take Home Points:


  • There are multiple factors to be considered in order to determine which procedure is right for you. It is important to have an open and honest conversation with your surgeon.

  • The Gastric Bypass has potential to yield better weight loss results with being more of an aggressive procedure, however the trade off is that it is a more complex surgery and has higher rates of vitamin and mineral deficiencies.

  • Both procedures require life long vitamin and mineral supplementation adherence and blood test monitoring.

  • No procedure will prevent weight regain. Weight loss surgery is a tool, not quick fix. To have successful long term weight loss you need to make the appropriate lifestyle changes.

  • How much weight loss you have in the first 12 months post surgery is a big predictor for how you will go long term. Studies have shown that those who stay engaged for regular follow ups with their Dietitian achieve better weight loss and food tolerance.


- Jacinta


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