Gastric Bypass Surgery

Gastric bypass is the most common type of bariatric operation performed across the world.Gastric bypass operations combine the creation of a small stomach pouch to restrict food intake and construction of bypasses of the duodenum and proximal segments of the small intestine to cause mal-absorption (decreased ability to absorb nutrients from food).


First, a small stomach pouch is created by stapling and dividing a part of the stomach together. This limits how much food you can eat. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum as well as the first portion of the jejunum. This causes reduced calorie and nutrient absorption. This procedure can now be done with a laparoscope (a thin telescope-like instrument for viewing inside the abdomen). This involves using small incisions and generally has a rapid recovery time.

How much weight will you lose after a gastric bypass?

Studies show that on an average, people lose between 60–70% of their excess weight in two years after gastric bypass surgery. The weight loss starts soon after the operation. The most of the weight loss happens during the first year and it gradually slows down as the BMI approaches towards healthy weight. It is possible but not easy to reach to a normal BMI range after a gastric bypass operation. If life style changes are made and adhered to for a long time then you will be able to reach to a healthy BMI of 25kg/m2 or lower.

The good news is that long before you reach that goal, you will start to feel the benefits, especially if you also have any of the obesity–related diseases such as diabetes, heart disease or high blood pressure. You will also have a much greater capacity for physical activity and more self–confidence.

Gastric bypass operations that cause mal-absorption and restrict food intake produce more weight loss than restrictive operations like Gastric Band which only decrease food intake. People who have bypass operations generally lose two-thirds of their excess weight within 2 years.

Gastric bypass is more a extensive operation and carries higher risks of early and late complications.

Results and health benefits of gastric bypass

Weight loss of 65 to 80% of excess body weight (the amount by which actual body weight exceeds actuarial ideal body weight) is typical of most large series of Gastric Bypass operations reported. The medically more significant effects are a dramatic reduction in co-morbid conditions:

  • Hyperlipidemia is corrected in over 70% of patients.
  • Essential hypertension is relieved in over 70% of patients, and medication requirements are usually reduced in the remainder.
  • Obstructive sleep apnea is markedly improved with weight loss, so that most patients are asymptomatic, and often do not even snore, within one year.
  • Diabetes mellitus type 2 is reversed in up to 90% of patients, usually leading to a normal blood sugar without medication, sometimes within days of surgery.
  • Gastroesophageal reflux disease is relieved from the time of surgery in almost all patients.
  • Venous thromboembolic disease signs such as leg swelling are typically much improved.
  • Low back pain and joint pain are typically relieved or improved in nearly all patients.

A recent study in a large comparative series of patients showed a 89% reduction in mortality over the 5 years following surgery, compared to a non-surgically treated group of patients. There were accompanying decreases in the incidence of cardiovascular disease, infections, and cancer.

Concurrently, most patients are able to alter their lifestyle, to consume "healthier" foods, exercise more regularly, and to enjoy greater participation in family and social activities. Bariatric surgery is the most effective treatment for morbid obesity, and can markedly improve health and lifestyle.

Who Should have Gastric Bypass operation?

According to NICE guidelines obesity surgery should be considered for patients with a BMI of greater than 40 without any comorbidity or BMI of 35 with one or more comorbidities like high blood pressure or diabeties. Patients should have tried dietary and other means to lose weight and have failed. Recent NICE guidlines recommend obesity surgery as a first line of treatment for patients with a BMI above 50. Gastric bypass operations are effective in reducing weight in all patients. However, this operation is more commonly used in patients with a BMI above 45.

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