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Bariatric or Weight-Loss Surgery - Introduction, Types, and Complications

Written by
Dr. Sneha Kannan
and medically reviewed by Dr. Noushif M

Published on Dec 03, 2019   -  7 min read



Bariatric or weight-loss surgeries are minimally invasive techniques that are done to achieve weight loss by reducing the size of your stomach. Read the article to know about the various types of weight-loss surgeries, its advantages and risks.

Bariatric or Weight-Loss Surgery - Introduction, Types, and Complications


Bariatric surgery are procedures done to reduce food intake in obese individuals, in order for them to lose weight. Body mass index (BMI) is used to determine if a person is obese or not. If a person’s BMI is over 30, he or she is classed as obese.

The common types of bariatric surgery are

  • Roux-en-Y gastric bypass.

  • Sleeve gastrectomy.

  • Laparoscopic adjustable gastric banding.

  • Duodenal switch with biliopancreatic diversion.

The most commonly used procedure amongst these is the gastric bypass. Here, the digestive system past the stomach is re-routed to suppress hunger and make the individual feel full. During the gastric band procedure, an inflatable band is placed around the upper portion of the stomach, which makes the stomach smaller. So people after getting this done feel full after eating less food. In sleeve gastrectomy, 80 % of the stomach is removed. This limits the food a person can eat at a time.

The recovery time varies depending on the patients, but it usually takes months to resume normal daily activities after the surgery. Most patients have to follow a liquid diet, after which they introduce solid food gradually. This surgery not only helps a person lose weight but also lowers the risk of heart problems, diabetes, stroke, etc., associated with obesity.

How Does Bariatric Surgery Help in Weight Loss?

Bariatric surgery helps in weight loss in the following two ways:

  • It physically limits the amount of food that the stomach can contain, this, in turn, limits the intake of calories.

  • The food that we eat gets absorbed into the body from the small intestine. This surgery also bypasses part of the small intestine, which reduces the number of calories absorbed.

What Are the Common Types of Bariatric Surgery Performed?

The common types of bariatric or weight loss surgery performed are:


It is otherwise called gastric bypass, and it is the most common type of surgery done to achieve weight loss.


Here, a small stomach pouch of around 30 ml is created by separating the top portion of the stomach from the rest, and the upper portion of the small intestine is also divided. After dividing the stomach and small intestine, the small stomach pouch is connected to the lower divided end of the small intestine. In the end, the top portion of the small intestine is connected further down to the lower end of the small intestine, which allows the stomach acids and digestive enzymes to mix with the passing food.

The small stomach pouch that is created holds less food, and as a part of the small intestine is bypassed, fewer nutrients and calories get absorbed by the body. The surgery also changes the hormones in the gut, which promotes satiety, suppresses hunger, and reduces the risk of type 2 diabetes.

Roux-En-Y Gastric Bypass

img-source :


  • Long-term weight loss of up to 60 to 80 % of excess weight.

  • It increases metabolism.

  • It restricts the amount of food intake.

  • The person feels full and appetite reduces.

  • Helps manage blood sugar levels in patients suffering from type 2 diabetes.

  • Most people can maintain more than 50 % of the weight lost in the long run.


  • A complicated surgery than the other options.

  • Can cause long-term vitamin and mineral deficiencies.

  • It takes longer for the patients to recover.

  • It requires the patients to restrict eating certain foods and taking vitamins or minerals life long.


It is otherwise called laparoscopic sleeve gastrectomy. In this procedure, around 80

% of the stomach is removed.


As almost 80 % of the stomach is removed, the remaining portion of the stomach is small, tubular and looks like a banana. It almost works similar to gastric bypass. The new and small stomach holds only very little food, so the patient eats less. Similar to gastric bypass, this also affects the gut hormone, resulting in satiety, blood sugar control, and less hunger.

This procedure also helps type 2 diabetes patients manage blood glucose levels independent of weight loss.

Sleeve Gastrectomy

img-source : mainehealth


  • It restricts the amount of food intake.

  • Weight loss can be achieved rapidly.

  • It does not require bypassing the food passage.

  • Patients can go home within a couple of days of surgery.

  • The changes in gut hormones suppress hunger, reduces appetite, and improves satiety.


  • It is non-reversible.

  • Might cause vitamin deficiencies.

  • The complications are more compared to the adjustable gastric band.


This procedure is otherwise called the band. Here, an inflatable band is placed around the upper portion of the stomach, which creates and separates a small portion of the stomach above the band from the rest of the stomach.


The distance between the band and stomach opening can be adjusted, which will determine the size of the stomach pouch. The smaller the distance, the lesser will be the food intake. If the stomach pouch is small, then eating a small amount of food will make the person feel full. This size of the stomach opening can be easily adjusted by injecting sterile saline.

The size of the stomach opening is adjusted slowly over time. In this procedure, normal digestion and absorption is not affected. It does not alter the gut hormones, thus it is not useful in controlling blood sugar levels. It only reduces the amount of food a person can consume at a time.

Adjustable Gastric Band

img-source : flushinghospital


  • It can help lose 40 to 50 % of excess weight.

  • The patient can go home in less than a day after the procedure.

  • Reduces calories by reducing the amount of food the stomach can hold.

  • It has the lowest rate of complications and mortality as compared to all other bariatric procedures.

  • There is no need to cut a part of the stomach or rerouting the small intestine.

  • The band can be removed and adjusted when needed.

  • It does not cause vitamin or mineral deficiencies.


  • Weight loss achieved is slower than other procedures.

  • In some patients, the band slips or results in its erosion into the stomach.

  • Some patients fail to lose 50 % of excess weight.

  • The band, which is a foreign device, has to be in the body throughout.

  • Most patients need a second operation.

  • If the patients overeat, it can dilate the esophagus.

  • It requires the patients to stick to a strict diet.


In this procedure, a small tubular stomach pouch is made by cutting of a large portion of the stomach, similar to sleeve gastrectomy. And then a portion of the small intestine is bypassed. This is considered to be the most effective to control blood sugar levels.


After sleeve gastrectomy is done, that is a large portion of the stomach is cut to make the remaining stomach to look like a small tubular structure or a banana, the first part of the small intestine (duodenum) is connected to a segment of the last portion of the small intestine. This is then connected to the outlet of new small tubular stomach. This allows the food that the patient eats to pass through the small stomach and reach directly to the last portion of the small intestine.

The gastric juices and enzymes in the small intestine is also carried to its distal end, where the food is digested and broken down. As the food is not digested until it reaches far down the small intestine, the amount of calories and nutrients absorbed is far less. And as the size of the stomach is small, the patient eats less. As the route of food is altered, it alters the gut hormones resulting in reduced hunger, increases satiety, and blood sugar control.

Duodenal Switch With Biliopancreatic Diversion

img-source : chennaimedtour


  • It results in almost 60 to 70 % of excess weight loss, and it the most effective among all the other weight-loss surgeries.

  • The patient eventually eats almost normal meals.

  • The amount of fat absorbed reduces to 70 %.

  • It is most effective in controlling blood glucose in diabetic patients.


  • It is the most effective, but can also result in the highest rates of complications and death.

  • The patients takes longer to recover.

  • It results in lifelong vitamin and mineral deficiencies.

What Are the Complications of Bariatric Surgery?

Some of the common complications include:

  • Patients have abdominal pain, diarrhea, and acid reflux after eating.

  • They eat a very limited amount of food throughout their life.

  • It can result in severe mineral and nutritional deficiencies.

  • Post-operative bleeding.

  • Infection in the incisions.

  • Formation of blood clots in the deep veins.

  • Ascites (collection of fluid and pus in the abdominal cavity) if the surgeon accidentally punctures the intestine or stomach.

  • Intestinal obstruction.

Always talk to a doctor before deciding on getting any of the above mentioned surgeries. Make sure you are aware of all the risks that are associated with it. For more information, consult a metabolic surgeon online now.

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Last reviewed at:
03 Dec 2019  -  7 min read


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