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Gastric Bypass Surgery - Types, Procedure, Indications, and Risks

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Gastric bypass surgery is a type of weight loss surgery. Read below to know more about gastric bypass surgery.

Written by

Dr. P. Saranya

Medically reviewed by

Dr. Ghulam Fareed

Published At October 18, 2022
Reviewed AtFebruary 23, 2024


Gastric bypass is a surgery that helps to lose weight. Gastric bypass surgery is done when diet and exercise have not helped reduce weight or serious health issues because of being overweight. After the surgery, the stomach will be smaller. The food will not go into some parts of the stomach and small intestine that will absorb food. The body will not get all of the nutrients from the food we eat. It is also known as bariatric bypass surgery.

What Are the Types of Gastric Bypass Surgery?

There are various types of gastric bypass surgery:

  • Roux-En-Y Gastric Bypass: This is one common type of gastric bypass surgery. Surgery is done under general anesthesia. In this procedure, the surgeon first makes a small stomach pouch by stapling part of the stomach or by vertical banding. Next, the surgeon attaches a Y-shaped portion of the small intestine to the pouch. This limits the amount of food you eat and creates a bypass for food, so it skips part of the digestive system.

  • Extensive Gastric Bypass: This is a complicated surgery. In this surgical procedure, the lower part of the stomach is removed. Then the surgeon connects the small pouch that remains to the last part of the small intestine. It works for weight loss, but this surgery is not done widely because it has high complications.

What Are the Ways of Doing Gastric Bypass Surgery?

Gastric bypass surgery can be done in two ways - open surgery and laparoscopic surgery.

In open surgery, the surgeon makes a large open cut in the abdomen. The bypass is done by accessing the organs through the large cut.

Another way is laparoscopic surgery, in which small cuts are made, and a laparoscope with a tiny camera is inserted through these cuts, which are used to see inside of the belly. Surgical tools are also inserted through the small cuts to perform the surgery. Laparoscopic surgery has advantages like less pain, quicker recovery, and a short hospital stay. The procedure takes about two to four hours.

Who Needs Gastric Bypass Surgery?

Gastric bypass is not done for everyone who is extremely overweight. Doctors use body mass index (BMI) and systemic conditions like diabetes mellitus and hypertension to determine the candidates for weight loss surgery.

The procedure is recommended under the following conditions:

  • People with a body mass index (BMI) of 40 or more. Someone with a BMI of 40 or more is at least 45kgs higher than the recommended body weight.

  • A body mass index (BMI) of 35 or more and a serious medical condition like type 2 diabetes, hypertension, and obstructive sleep apnea.

What Happens Before the Surgery?

  • Before the surgery, a complete physical examination is done.

  • Blood tests and ultrasound are done to confirm the eligibility for surgery.

  • Medical problems such as diabetes and blood pressure should be under control.

  • A urine catheter is placed in the bladder to drain urine.

  • Quit smoking a few weeks before the surgery.

  • Inform the doctor about your pregnancy and the vitamin and herbal supplements you are taking.

  • Inform the doctor about the medications you are taking, such as blood thinners like Aspirin, Clopidogrel, and Warfarin. These drugs should be stopped for a few days before the surgery.

What Happens After the Surgery?

Patients will stay in the hospital for one to four days after the surgery. The patient can not eat for one to three days after the surgery. After that, liquid foods are first given, and then solid foods are introduced. Special stockings are worn on the leg to prevent the formation of blood clots. Painkillers and antithrombotics are given.

What to Eat After the Surgery?

Gastric bypass surgery reduces the size of the stomach and changes the way food enters the intestine. After surgery, it is important to get enough nutrients while maintaining the weight-loss goals on track.

  • Eat and Drink Slowly: Eat the meals for at least 30 minutes and take 30 to 60 minutes to drink one cup of liquid. This can avoid dumping syndrome. You may have to wait for 30 minutes before or after each meal to drink liquids.

  • Keep Meals Small: Eat multiple numbers of small meals a day. Start with six meals a day, then four meals, and finally regular, three meals.

  • Drink Liquids Between Meals: Drink at least eight cups (1.9 liters) of fluids a day to prevent dehydration. But do not drink more fluids during mealtime.

  • Chew Food Thoroughly: Eat small bites of food and chew them thoroughly before swallowing to avoid blockages in the new opening from the stomach to the intestine.

  • Focus On High-Protein Foods: Eat protein-rich foods.

  • Avoid Foods That Are Rich in Fat and Sugar Content: These foods can cause dumping syndrome.

  • Take Recommended Vitamin and Mineral Supplements: Multivitamin supplements are taken daily for the rest of your life.

What Are the Risks of Gastric Bypass Surgery?

Gastric bypass is major surgery, and it has many risks.

  • Pouch Stretching: The stomach stretches and changes to its original position over time.

  • The staples fall apart.

  • Allergic reactions to anesthesia.

  • Gastritis, stomach ulcers, or heartburn.

  • Injury to the stomach, intestine, or other organs during surgery

  • Nutritional, vitamin, and mineral deficiencies.

  • Stomal Stenosis: A narrowing at the connection of the stomach and small intestine causing nausea, and vomiting

  • Gastric bypass surgery also causes a dumping syndrome, in which the food moves too quickly from the stomach to the small intestine.

What Is the Alternative for Gastric Bypass Surgery?

Endoscopic sleeve gastroplasty is a newer type of weight-loss procedure. This is a minimally invasive procedure. The procedure uses a flexible tube attached to a camera and an endoscopic suturing device. The endoscope is inserted down the throat into the stomach.

The doctor places sutures in the stomach using the endoscope. The sutures change the stomach making it smaller. This restricts the amount of food you eat.


Gastric bypass can provide long-term weight loss. The surgery also improves daily activities and the quality of life. It improves or resolves health conditions related to overweight issues. This surgery is irreversible in most cases.

Frequently Asked Questions


What's the Minimum Weight for Gastric Bypass?

A body mass index (BMI) between 35 and 40 is the minimum BMI required for undergoing gastric bypass surgery with an obesity-related condition, such as severe sleep apnea, high blood pressure, diabetes, or heart disease. In addition, weight should be less than 204 kilograms, the maximum weight that hospital radiology equipment can accommodate.


Is Gastric Bypass Surgery a Serious Medical Procedure?

Yes, gastric surgery is serious surgery. It is a major surgery involving various risks, such as stomach lining inflammation (gastritis), heartburn, ulcers, poor nutrition, and vomiting. Also, fluid can leak from the stomach lining where it has been stapled.


What Is Life Expectancy After Gastric Bypass?

According to the studies, the life expectancy after gastric bypass surgery is higher when compared to obese patients. However, the mortality rate in both cases is still higher than the normal population. In addition, an individual's median average life span after gastric bypass surgery compared to the control group is three years.


What Are 3 Common Long-Term Complications of Gastric Bypass?

The three common long-term complications of gastric bypass surgery are bowel obstruction, dump syndrome, and gallstones. Other complications include poor nutrition, lung or breathing problems, blood clotting, infections, and leaks in the gastrointestinal system.


What Does a Gastric Bypass Leak Feel Like?

Gastric bypass is weight-loss surgery. During the surgery, the stomach is reduced to a small gastric pouch, and the loop of the small intestine is cut, brought up, and connected to the gastric pouch. Food is then rerouted to an area much lower in the digestive system and bypasses the stomach. As the food bypasses the stomach, the body does not absorb as many calories. As a result, you will feel full much faster than before after eating.


What Is a Possible Downside to Having a Gastric Bypass?

- Pouch Stretching: The stomach stretches and changes to its original position over time.
- The staples fall apart.
- Allergic reactions to anesthesia.
- Gastritis, stomach ulcers, or heartburn.
- Injury to the stomach, intestine, or other organs during surgery.
- Nutritional, vitamin, and mineral deficiencies.
- Stomal Stenosis or narrowing at the connection of the stomach leads to nausea and vomiting.
- Gastric bypass surgery also causes dumping syndrome, in which the food quickly moves from the stomach to the intestine.


Can I Eat Sugar After Gastric Bypass Surgery?

Eating sugar or high-fat food after gastric bypass surgery can cause dumping syndrome. In this syndrome, food high in sugar and fat enters and moves speedily from the stomach into the small intestine. If a large amount of food enters the small intestine quickly, causing vomiting, nausea, dizziness, sweating, and diarrhea. High-fat or high-sugar food on consumption causes nausea and vomiting after meals.


Can You Vomit After Gastric Bypass?

Vomiting and food intolerance are common occurrences early on after gastric bypass surgery. This normally happens due to the narrow gastro-jejunostomy. The passage is narrow while healing, so it can cause vomiting.


Can You Drink Alcohol After a Gastric Bypass?

Alcohol should be completely avoided for the first six months after the surgery. After that, a physician's advice should be sought before starting the intake of alcohol. In addition, carbonated drinks and other high sugar-containing drink mixers should be avoided.


How Often Should You Pass Stools After Gastric Bypass?

Bowel movements should be normal and tracked after the gastric bypass surgery. Many people suffer from constipation after the surgery. Stools should be passed once every day.


Which Is Better, the Sleeve or the Gastric Bypass?

In the long run, gastric sleeve surgery has lesser complications and risks of death. Also, patients with sleeve surgery needed follow-up surgery. Both surgeries have a 50 % to 80 % success rate. It is always better to discuss which surgery suits you with the healthcare provider and then opt for it.


Is the Gastric Bypass Worth It?

Gastric surgery is worth undergoing in patients with complicated weight loss patterns. It is a boon for people with a body mass index (BMI) of 40 or more. Someone with a BMI of 40 or more is at least 45 kgs higher than the recommended body weight.


What Percent of Gastric Bypass Patients Gain the Weight Back?

The early weight loss following a gastric bypass surgery ranges from 47 % to 80 % of excess weight. Moreover, a typical weight regain is 15 % to 25% of that lost weight. This can be bad news for patients undergoing gastric bypass surgery, and managing weight expectations post-surgery is very important.


How Big Is Your Stomach After Gastric Bypass Surgery?

Gastric bypass surgery helps reduce weight by changing the pattern of food absorption in the stomach and small intestine. Post-surgery, the stomach becomes smaller in size. There is early satiety with less food intake. And the food consumed will no longer go through some parts of the stomach and small intestine that absorb food.


Can Your Stomach Grow Back After Gastric Sleeve?

No, the stomach does not grow after gastric sleeve surgery. However, it allows the patient to have a long-term normal life once they achieve their weight loss success.
Dr. Ghulam Fareed
Dr. Ghulam Fareed

Medical Gastroenterology


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