The Gastric Bypass (BPG) is a surgical procedure for the treatment of obesity categorized as MIXED, since it combines a restrictive element (decreases the amount of food that can be ingested), with a malabsorptive component (it does not allow most of the ingested food be absorbed by the body). It is the oldest operation, since 1966, it has passed the test of time, being the only operation that has been carried out for more than 30 years. It is considered the “Golden Standard” of obesity surgery and in recent years many details have been improved that make it safer and more effective.

Mechanism of Operation and Surgical Technique

Operations against obesity are categorized into two types: Restrictive and Malabsorption. The first category (restrictive) limits the amount of calories or food ingested, reducing the stomach space available to accommodate food. The second, malabsorption, reduces the absorption of food that has already been consumed. Gastric bypass surgery combines a gastric restriction procedure with a small portion of malabsorption.



The surgeon reduces the size of the stomach, dividing it into a small upper bag that will act as a “new stomach” and a larger lower section, using a special stapler. After dividing the stomach, the surgeon connects the small intestine to the small pouch that will act as a “new stomach,” so that the flow of food skips the lower portion of the “former stomach.” Finally, the surgeon reconnects the portion that comes from the new small bag with the remaining portion of the small intestine that comes from the lower part of the “former stomach”, forming a Y-shaped figure. This “Y-shaped connection” allows food to mix with pancreatic fluid and bile, thus helping the absorption of important vitamins and minerals. Even so, the person may still experience poor absorption of certain nutrients.


  • As the stomach becomes smaller, the person experiences a more rapid feeling of fullness.
  • Also when a stomach is smaller, the person naturally reduces the amount of food they eat.
  • The cancellation of an important part of the digestive tube produces mal-absorption of calories.
  • The person experiences a change in eating habits, due to the “gastric evacuation syndrome” (nausea, sweating, weakness and diarrhea) that will induce the consumption of foods with high caloric content. This syndrome is caused by any overdose of calories that reaches the small intestine.
  •  Patients lose two thirds of their excess weight in two years, 60% in 5 years, and more than 50% in 9 years.
  • It is a very effective method to fight against morbid obesity, especially in patients addicted to sweets.

    Risks of Surgery: Morbidity is exactly like any abdominal surgery. Serious complications such as leakage and thrombosis are much less than 1%. The complications that produce severe obesity are much more risky than, NOT GETTING THE OPERATION.

    Gastric Bypass by Laparoscopy

    Laparoscopic surgery is a surgical technique that involves performing operations of organs inside the abdomen or the wall of the abdomen, through support with cameras, lighting and small-sized lenses that transmit the images to monitors, where The surgeon observes and through which he performs the desired surgery.
    Since 1988 it has been carried out around the world, it is a well-known technique that has progressively been improved, it has been applied to different pathologies and different organs, supported by the constant improvement of equipment and instruments, as well as in the design of new technology that makes it possible to perform more complex surgeries, with highly satisfactory results.


    • All of the gastric bypass have very good weight loss in most patients for many years.
    • A low rate of long-term reoperations.
    • All should be done laparoscopically (minimal scar, minimum pain, early discharge).


    • Higher cost in instruments.
    • A difficult learning curve for surgeons.
    • It can be very difficult or impossible in super obesity.

    Not only weight is lost but co-morbidities are improved, such as diabetes, obesity-related apnea syndrome, hypertension and elevated cholesterol and triglyceride abnormalities. It also improves cardiac function and the size of the cardiac wall. Other important benefits are the improvement of mobility and resistance in general. Improves self-esteem, humor, interpersonal relationships, the ability to work and find work. The change that the individual has of his body image allows him to explore social, vocational and personal relationship activities. There is an important improvement in couples relationship, if they were good beforehand.

    The effects on health and well-being in short and long term are extraordinary. Adult diabetes is cured, hypertension is improved or cured, sleep apnea disappears, many sterile patients become pregnant, urinary incontinence is corrected, joint pain is improved, etc.


    Gastric restrictive operations need education, motivation and cooperation of the patient to maintain an adequate intake of proteins, calories, minerals and vitamins. At 3 months there is a moderate protein deficit that disappears at 18 months, when the final weight has already been restored. Diets depend on the type of operation. Operations with rings force for life style change that restric the quality of meals and what they eat (meat, bread, dry rice, etc.). Mixed operations, as they do not use rings, have a better quality of life and diets. The gastric bypass is between the two extremes.

    All restrictive operations, simple operations, force the patient to chew very well and very slowly if they do not want to vomit. In the first 3 months, if they vomit a lot, they may suffer mild overall nutritional deficits. In bypass and mixed operations, we must be careful that patients do not develop iron deficiency, anemia, Vitamin B12, calcium and fat-soluble vitamins. Therefore, it is desirable to carry out a continuous analytical follow-up so that if deficits are detected, they can be replaced. Malabsorption techniques have as a side effect the bad odor of feces.