Gastric bypass surgery is the most commonly performed weight loss surgery or bariatric surgery in the US today and combines the restrictive as well as the malabsorptive approaches which have been explained in the post on bariatric surgery. This bariatric surgery offers the choice of performing an open operation as well as through the laparoscope. It is primarily indicated in people with morbid obesity.

It is called by many names:

  • Gastric bypass.
  • Gastric bypass surgery.
  • Gastric bypass operation.
  • Stomach bypass operation.
  • Gastroduodenal bypass surgery.
  • Abdominal bypass surgery.
  • Gastrointestinal bypass surgery.
  • Roux-en-Y.
  • Roux-en-Y gastric bypass.
  • Gastric Bypass Surgery

There are various weight loss surgeries but gastric bypass operations are the most frequently performed because they pose lesser complications.

Lap band surgery is performed nearly as often as gastric bypass and offers the same benefits. While lap gastric banding solely restricts the size of the stomach, gastric bypass uses restriction and reduces calorie absorption.

Gastric bypass surgery or any weight loss surgery can provide you with sustained weight loss only if you are consistent in your healthy eating habits and exercise on a regular basis during life after the surgery.

Gastric bypass surgery is a major surgery and is not without the possibility of risks which include infection, blood clotting, and hernia.

However, not everybody can benefit from gastric bypass surgery because the end result requires you to make certain everlasting changes in your lifestyle. And for that, a motivated and dedicated weight loss patient is required for a successful long-term prognosis.

Aim of gastric bypass | Why is it done?

Gastric Bypass is done to achieve three goals.

  1. It helps to bring about a significant reduction in morbid obesity.
  2. It reduces the health risks associated with obesity like high blood pressure, sleep apnea, diabetes, GERD, etc.
  3. It brings down the early mortality risk which is prevalent in obesity. You could read these obesity mortality prevalent statistics in obesity and life expectancy.


Not everybody can undergo a gastric bypass operation. There are certain factors that make you eligible for this surgery. They are mentioned below:

  • Age between 18 years and 55 years.
  • A history of obesity of up to 5 years.
  • You are morbidly obese. That is you have a BMI of  40 or more. Or your excess weight is 100 lbs more than what your weight should be in men and 80 lbs more in women.
  • You do not consume excess alcohol.
  • You have a BMI between 30 to 40 along with anyone obesity health risks such as diabetes, high cholesterol, high blood pressure, sleep apnea, etc.
  • Have religiously tried to lose weight with a weight-loss diet and weight-loss exercises without satisfactory results.
  • Have understood and are ready to accept the risks associated with bariatric surgery.
  • Are ready to follow the lifelong dietary requirements for long-term success.

Gastric bypass surgery | Roux-en-y

  • Anesthesia: General.
  • Method of surgery: Either with a laparoscope or by open surgery.
    • Laparoscopic gastric bypass surgery involves using four to five small incisions on the abdomen and the insides are viewed on a screen with the help of a camera attached to the laparoscope, which is inserted through one of the incisions.
    • In the open method, one large incision is made and the abdominal contents are exposed for direct viewing.
  • Duration of gastric bypass surgery: In an uncomplicated case, it takes about 2 hours if done with a laparoscope. The open procedure will take a little longer.
  • Hospital Stay is for two to three days or slightly more in an uncomplicated case. The patient can resume his or her normal activity and duties within 3 to 5 weeks. You will be discharged only if
    • You can eat soft food without vomiting.
    • You can walk without pain.
    • You do not need medicines and nutrition through I.V. fluids.

Gastric bypass procedure

In this surgery, the stomach is divided into two parts either by suturing or by using surgical staples ( stomach stapling) – the upper smaller pouch and the lower larger pouch. The upper smaller pouch, which is the size of one’s thumb, is then connected to the lower part of the small intestine. The lower part of the stomach and the upper part of the small intestine are bypassed during the passage of food.

This technique is called “roux-en-Y” because of the Y shape that is formed by the anastomosed small intestine. As a result of this bypass, food bypasses the lower pouch of the stomach, the duodenum, and the first part of the jejunum.

This surgery can be performed by the open procedure where the abdomen is opened by making a large incision. It is also performed more commonly by using a laparoscope in which case 4 to 5  small incisions are made for other surgical instruments.

This operation makes use of two approaches:

  • Restrictive approach. Because the upper pouch of the stomach is small, you feel full on eating very less food. You, therefore, consume fewer calories.
  • Malabsorptive approach. Secondly, since the upper part of the intestine is bypassed, the food that you eat passes from the upper pouch of the stomach directly into the second part of the jejunum. There is therefore a lesser area of the gastrointestinal tract for the absorption of calories. It is the duodenum that is bypassed where the majority of the calories and nutrients are absorbed. This is the malabsorptive approach.

The stapling or suturing of the stomach and bypassing it are the two procedures which together are called roux-en-Y gastric bypass and form two procedures of this surgery. This is the most commonly followed weight loss surgery in the U.S. and accounts for 80% of all bariatric surgeries.

The success rate on weight loss

A weight loss surgery can be defined as successful when

  • Excess weight is reduced by 50%, and
  • This 50% weight loss is sustained for 5 years after that. For example, if you are 100 lbs overweight, then you should lose 50 lbs and this weight loss should be maintained for another 5 years.

Going by estimations, one to two years after the gastric bypass, loss of excess weight is to the tune of 50% to 66%, and 50% loss of excess weight is documented at 10 years or more after surgery. 65% to 85% loss of excess weight is also reported in some cases.

Health benefits of gastric bypass in obesity

Besides the benefits of weight loss post gastric bypass surgery, other benefits also accrue vis-à-vis the complications of obesity.

  • Diabetes type 2, which had developed due to obesity, is reversed in 90% of the people, leading to normal sugar levels without medication. This can occur within days of the surgery.
  • High blood pressure is lowered in 70% of the patients and in others, medicine doses are lowered.
  • High cholesterol levels and high triglyceride levels are corrected in 70% of the patients.
    Sleep apnea and snoring which are also complications of obesity also improve due to weight loss post gastric bypass.
  • GERD is relieved post-surgery immediately.
  • Swelling of the legs due to venous thrombosis also improves.
  • Low back pain and arthritis pain due to obesity also show marked improvement.
  • Life expectancy due to obesity which was reduced improves markedly. A recent study claims an 89% reduction in mortality over 5 years after surgery.
  • Social participation improves due to a sense of achievement.

Complications and risks

Gastric bypass patients are exposed to certain risks and complications due to the surgery.

  • Wound infection
  • Food intolerance
  • Nutritional deficiency.
    • Anemia can result due to inadequate absorption of iron and vitamin B12,
    • Neurological symptoms can occur due to inadequate absorption of vitamin B and
    • Bone weakness can occur due to a deficiency of calcium and vitamin D.
  • A deficiency of proteins, vitamins, and minerals also occurs and should be supplemented with supplements.
  • Dehydration occurs because the patient is unable to drink much fluid at one time.
  • Body aches and a feeling of tiredness due to a deficiency of calories
  • Mood swings
  • Dry skin
  • Thinning of hair and hair loss.
  • An incisional hernia occurs when weakness develops in the area around the incision. This is more common when open surgery is performed rather than a laparoscopic procedure.
  • Bowel obstruction due to adhesions.
  • Gallstones can develop. Therefore, many times, cholecystectomy (removal of gall bladder) is advised before gastric bypass.
  • Kidney stones may develop.
  • Post-bariatric surgery hypoglycemia (low blood sugar) is a rare but serious complication. If symptoms of hypoglycemia develop, the patient should immediately inform his attending physician. If medicines and diet therapies do not work, surgical removal of the pancreas improves this condition. This complication is called Non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS).
  • An ulcer may develop where the small intestine is attached to the upper part of the stomach. This is not a common complication.
  • Stomal stenosis is when the opening between the stomach and bypass is too tight or narrow. Vomiting is the first symptom. This can be repaired in the outpatient department by dilating the opening by passing a tube or rarely a small surgery may be required.
  • Blood clots in the legs can cause deep vein thrombosis leading to pulmonary embolism. This risk can be reduced by exercising the legs by walking and exercising the ankle joints.
  • Leakage from the anastomosis can lead to peritonitis due to the spillage of gastric contents into the abdomen. This requires an emergency operation to repair the leak.
  • Dumping syndrome wherein the food moves quickly through the small intestine causing nausea, vomiting, and diarrhea.
  • Gastric bypass and alcohol. Gastric bypass patients absorb alcohol at a faster rate and recovery from alcohol intoxication (that is time to sober up) is slower than in patients who have not undergone this surgery.
  • 1% chance of death due to the surgery which can occur within one month of the surgery, especially after an open gastric bypass.