What is Gastric Bypass?

Gastric bypass and other weight loss surgeries – collectively known as bariatric surgery – involve making changes to your digestive system to help you lose weight. Bariatric surgery is performed when diet and exercise do not work or you have serious health problems due to your weight. Some procedures limit how much you can eat. Other procedures work by reducing the body’s ability to absorb nutrients. Some procedures do both.

While bariatric surgery can bring many benefits, all types of weight loss surgery are important procedures that can pose serious risks and side effects. In addition, to ensure the long-term success of bariatric surgery, you should make permanent healthy changes to your diet and exercise regularly.


Biliopancreatic diversion with a duodenal switch (BPD / DS)

Gastric bypass (Roux-en-Y)

The branch of gastrectomy

Bariatric surgery is performed to help you lose excess weight and reduce your risk of potentially life-threatening weight-related health problems.

Heart disease and stroke


Non-alcoholic fatty liver disease (NAFLD) or non-alcoholic steatohepatitis (NASH)

Sleep apnea

Type 2 diabetes

Bariatric surgery is typically performed only after you have tried to lose weight by improving your diet and exercise habits.

For whom

In general, bariatric surgery may be an option for you in the following cases:

  • Your body mass index (BMI) is 40 or higher (extreme obesity).
  • Your BMI is between 35 and 39.9 (obesity) and you have type 2 diabetes, high blood pressure, severe sleep apnea and a serious weight related health problem. In some cases, if your BMI is 30 to 34 and you have serious weight-related health problems, you may be eligible for certain types of weight loss surgery.
  • Bariatric surgery is not for everyone who is overweight. To qualify for weight loss surgery, you may need to follow certain medical guidelines. You will likely have a thorough screening process to see if you qualify. You should also be willing to make permanent changes to maintain a healthier lifestyle.
  • You may need to participate in long-term follow-up plans that include monitoring your nutrition, lifestyle and behaviour and your medical condition.

How are you preparing

If you qualify for bariatric surgery, your medical team will give you instructions on how to prepare for your specific type of surgery. Before surgery, you may need to undergo various laboratory tests and examinations. You may have restrictions on eating, drinking and medications you can take. You may need to start a physical activity program and stop using all types of tobacco.

You may also need to prepare for your recovery after surgery by planning in advance. For example, if you think you will need it, get help at home.



What can you expect

Bariatric surgery is performed in the hospital using general anesthesia. This means that you are unconscious during the procedure.

The specifics of your surgery depend on your personal situation, the type of weight loss surgery you have and the practices of the hospital or doctor. Some weight loss surgeries are performed with traditional large or open incisions on your abdomen.

Currently, most types of bariatric surgery are performed laparoscopically. A laparoscope is a small, tubular instrument with a camera attached to it. The laparoscope is inserted through small incisions in the abdomen. The tiny camera at the end of the laparoscope allows the surgeon to see and process the inside of your abdomen without making traditional large incisions. Laparoscopic surgery can make your recovery faster and shorter, but it is not suitable for everyone.

The operation usually takes several hours. After the operation, you wake up in a recovery room, where the medical staff is monitoring you for any complications. Depending on your procedure, you may need to stay in the hospital for several days.

Types of bariatric surgery

Every bariatric surgery has its pros and cons. Be sure to talk about them with your doctor. Here is a look at the common types of bariatric surgery:

  • Roux-en-Y (roo-en-wy) gastric bypass. This procedure is the most common method of gastric bypass. This surgery is typically irreversible. It works by reducing the amount of food you can eat in one sitting and reducing the absorption of nutrients.
  • The surgeon cuts the upper part of your stomach, separating it from the rest of your stomach. The resulting pouch is about the size of a walnut and can hold only about an ounce of food. Normally, your stomach can hold about 3 liters of food.
  • Then the surgeon cuts out the small intestine and sews part of it directly onto the sac. The food then goes to this small stomach pouch and then to the small intestine, which is sewn directly to it. Food bypasses most of your stomach and the first part of your small intestine and instead enters directly into your middle section.