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

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

5 min read


Bariatric surgeries achieve weight loss by reducing the size of the stomach. Read the article to know more about them.

Medically reviewed by

Dr. Noushif. M

Published At December 3, 2019
Reviewed AtFebruary 2, 2024

What Is Bariatric Surgery?

Bariatric surgery is a procedure done to reduce food intake in obese individuals to allow them to lose weight. Body mass index (BMI) determines whether a person is obese. If a person’s BMI is over 30, they are classed as obese. The recovery time varies depending on the patient, but it usually takes months to resume normal daily activities after the surgery. Most patients have to follow a liquid diet, introducing solid food gradually. This surgery helps a person lose weight and 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 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 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 gastric bypass. Here, the digestive system past the stomach is re-routed to suppress hunger and makes the individual feel full. During the gastric band procedure, an inflatable band is placed around the stomach's upper portion, making the stomach smaller. Therefore, people eat less and feel full after undergoing this procedure. In sleeve gastrectomy, 80 % of the stomach is removed, limiting the food a person can eat at a time.

What is Roux-en-Y Gastric Bypass?

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

Procedure - 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 small intestine's top portion is connected further down to the small intestine's lower end, allowing 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.


  • 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 his appetite reduces.
  • Helps manage blood sugar levels in patients suffering from type 2 diabetes.
  • Most people can maintain more than 50 % weight loss in the long run.


  • A complicated surgery than the other options.
  • It can cause long-term vitamin and mineral deficiencies.
  • It takes longer for the patients to recover.
  • It requires the patients to restrict their diet to certain foods and take vitamins or minerals lifelong.

What Is Sleeve GastrectomySurgery?

It is otherwise called laparoscopic sleeve gastrectomy. In this procedure, around 80 % of the stomach is removed.

Procedure - 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 similarly to gastric bypass. The new and small stomach holds very little food, so the patient eats less. Like 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.


  • 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, reduce appetite, and improve satiety.


  • It is non-reversible.
  • It might cause vitamin deficiencies.
  • The complications are more compared to the adjustable gastric band.

What is Adjustable Gastric Band Surgery?

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.

Procedure - The distance between the band and stomach opening can be adjusted, determining the size of the stomach pouch. The smaller the distance, the lesser will be the food intake. If the stomach pouch is small, 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 and is adjusted slowly over time. In this procedure, normal digestion and absorption are 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.


  • It can help lose 40 % to 50 % of excess weight.
  • The patient can go home in less than a day after the procedure.
  • It reduces calories by reducing the amount of food the stomach can hold.
  • It has the lowest complications and mortality rate compared to all other bariatric procedures.
  • There is no need to cut a part of the stomach or reroute 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 that by 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, a foreign device, has to be in the body throughout.
  • Most patients need a second operation.
  • If the patient overeats, it can dilate the esophagus.
  • It requires the patients to stick to a strict diet.

What Is Duodenal Switch With Biliopancreatic Diversion?

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

Procedure - After sleeve gastrectomy is done, that is, a large portion of the stomach cut to make the remaining stomach look like a small tubular structure or a banana, and 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 the new small tubular stomach. This allows the patient's food 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 are 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 stomach size is small, the patient eats less. As the food route is altered, it alters the gut hormones, reducing hunger, increased satiety, and blood sugar control.


  • It results in almost 60 % to 70 % of excess weight loss and is 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 procedure, but it can also result in the highest rates of complications and death.
  • The patients take 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.


The weight after bariatric surgery depends on the individual and the type of surgery performed. Most people may regain some weight over time. However, the amount is often small compared to the initial weight. Achieving weight goals depends on not only surgery but also lifestyle.

Frequently Asked Questions


What Is Bariatric Surgery?

Bariatric surgeries are done to reduce weight by reducing the size of the stomach. This procedure helps reduce the food intake of people who are obese, thereby helping them lose weight. Reducing weight in obese people can lead to better outcomes, like lowering the risk of diabetes, stroke, and heart problems.


What Are the Advantages of Bariatric Surgery?

Bariatric surgery helps obese individuals lose weight. The size of the stomach is reduced in this surgery, thereby reducing the food intake, which eventually leads to weight loss. There will be long-term weight loss of up to 60 to 80 percent of excess weight. It also helps boost the metabolism and helps reduce appetite.


How Can Bariatric Surgery Be Classified?

The four types of bariatric surgery include:
- Sleeve gastrectomy (a major portion of the stomach is vertically resected and a tube-shaped remnant is left in the lesser curvature).
- Roux-en-Y gastric bypass (a gastric pouch is connected with the small intestine bypassing the duodenum, stomach, and proximal part of the jejunum).
- Laparoscopic adjustable gastric banding (in the upper part of the stomach, a band is placed to create a small pouch that can hold food).
- Duodenal switch with biliopancreatic diversion (80 percent of the stomach is removed and a small tube-shaped portion of the stomach is left).
Out of these, the most common type of surgery is a gastric bypass. In sleeve gastrectomy, about 80 percent of the stomach is removed.


Is Bariatric Surgery Considered Safe?

Bariatric surgeries have been found to be the safest procedure for weight loss in obese patients. However, the risks of surgery are still there. Some complications that can occur during or after surgery include blood clots, internal bleeding, and infection.


What Is the Success Rate for Bariatric Surgery?

With sleeve gastrectomy, about 80 percent of the stomach is removed, thereby limiting food intake. As a result, there will be a long-term weight loss of up to 60 to 80 percent of body weight. Most people will be able to maintain more than 50 percent weight loss in the long run.


What Is the Duration of Bariatric Surgery?

The duration of bariatric surgery can take from one to two hours approximately. This can vary between different surgical techniques and also in different hospitals. Patients will attain recovery within three to four weeks.


What Is the Weight Range for Undergoing Bariatric Surgery?

People with a body mass index of 35 or higher are considered suitable for this surgery. Individuals with a BMI ranging from 30 to 35, along with conditions like heart disease, diabetes, severe sleep apnea, and indicated for weight loss surgery, can also undergo this procedure.


Which Is Considered the Best Long-Term Bariatric Surgery?

Gastric sleeve surgery is the most common type and has a high success rate. It is also considered a safe procedure. With sleeve gastrectomy, about 80 percent of the stomach is removed, and weight loss can be maintained.


How to Lose Weight the Best Way?

Losing weight can be done naturally by altering certain habits and including a few lifestyle changes. Some tips for natural weight loss are:
- Eating a healthy balanced meal without skipping any meal.
- Reduce intake of processed foods.
- Avoid junk foods.
- Sleep eight hours a day.
- Exercise regularly.
- Stay active and hydrated throughout the day.


Is Bariatric Surgery Everlasting?

The bariatric surgical procedure is permanent and cannot be reversed. It can help the individual to maintain weight for up to ten years. However, weight loss from bariatric surgeries is not permanent unless the individual follows some lifestyle modifications to maintain weight. However, Roux-en-Y gastric bypass operations are risky but reversible.


Are Weight Loss Surgeries Healthy?

Surgery should not be considered when there is a natural way to lose weight. Bariatric surgeries have some potential disadvantages, like vitamin deficiencies and decreased appetite. There can be surgical complications during procedures like this.


What Foods Are Weight-Loss Friendly?

Eating the right portion of food only when hungry can help in weight loss. Overeating or skipping meals are two extremes that can influence the weight loss journey. Some of the foods that can help maintain weight are:
- Whole eggs.
- Leafy green vegetables.
- Chicken breast.
- Tuna.
- Beans and legumes.
- Nuts.


What Is the Recovery Period for Bariatric Surgery?

The hospital stay after surgery can be from two to three days for most individuals. The patient can return back to normal activities only after three to five weeks of rest. However, in some individuals, it can extend up to six weeks for complete healing.
Source Article IclonSourcesSource Article Arrow
Dr. Noushif. M
Dr. Noushif. M

Surgical Gastroenterology


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