Results of the Gastric bypass against obesity

Written by: Dr. Alfredo Alonso Poza
Published: | Updated: 14/11/2018
Edited by: Anna Raventós Rodríguez

The Gastric by-pass procedure is a mixed technique of obesity surgery. It consists of combining a small gastric reservoir in the upper part of the stomach (restrictive technique) and attaching it to the small intestine by making a 1.5 meter bypass (malabsorptive technique), thus altering the process of digestion and providing the patient with a feeling of satiety important. Gastric bypass surgery obtains very good results, especially in patients with a Body Mass Index (BMI) between 45 and 55.


After this operation of obesity, the patient feels full and without hunger with much less food, so that an enormous loss of weight is achieved by the drastic reduction in the amount of food ingested and also by the worse absorption that is given to Get the food to the small intestine without passing through the duodenum.


Diet after Gastric Bypass

After undergoing a gastric by-pass, you need to reduce your calorie intake to a maximum of 1000-1200 calories per day to optimize results. The surgical intervention of the By-pass reduces the size of the patient's stomach, so that the reduction of food is greatly facilitated.


These are the general rules that must be followed during the postoperative period:

  • Always follow the dietary recommendations of the Nutrition Unit or the surgeon. Usually the new amount of food will be half or a third of a normal serving.
  • Take the habit of making 5 or 6 meals a day with little amount of food.
  • Like the tubular gastrectomy, with the Gastric By-pass during the first fortnight at home a liquid diet must be established based on broths, infusions and water. During this liquid day you should avoid dairy and fizzy drinks. It is also advisable to replace sugar with other sweeteners such as panela or maple syrup.
  • By the second fortnight you can start the pureed diet. Patience is required throughout this process, as the digestive tract is still in the adaptation phase.
  • It will be from the fourth week after the operation when you can start to ingest soft diet well crushed, and as now, in small quantities.
  • From the sixth week onwards the phased diet prescribed by the surgeon begins, and is generally based on avoiding fats, sausages, fried foods, sweets, bread, potatoes, pizza and pasta, soft drinks, Ice cream and alcoholic beverages.
  • From the third month onwards, a stage begins to vary food to find those that are better tolerated. In the best case the patient will be able to eat almost everything in small amounts, but in the worst cases some foods can cause nausea and vomiting.


Recommended foods after a By-pass

  • Chicken, turkey, white fish and lean meat are a great source of protein, as well as milk and eggs (animal origin). The best way to cook these foods is grilled or steamed. Patients who do not tolerate these foods to maintain adequate protein value may resort to soybeans, which are proteins of plant origin.
  • Legumes are very healthy in the diet, but can cause gas and heavy digestions.
  • The intervention can cause constipation, so to prevent it, take plenty of fluids, diuretic vegetables and fruit like prunes, kiwis, pears and oranges.
  • Intervention can also produce lack of calcium. To prevent this, the patient can use skim milk, yoghurts and fresh cheese. Skim milk enriched with calcium is especially recommended.
  • The fundamental step throughout the diet is to eat small amounts and chew very well. If any food is bad for the patient, you should wait at least six weeks before repeating it again to see if you can tolerate it.


Recovery after obesity surgery

After hospital discharge, it is necessary that the patient undergoing a Gastric By-pass perform a series of measures to relieve discomfort, protect the stomach and prevent blood clots. Walking a little each day will help a better recovery, while daily hygiene of the wounds should be done in the shower with water and neutral soap, without rubbing and leaving them in the air to prevent them from becoming infected.


The type of operation against obesity can provoke deficit of iron, calcium and vitamins. A multidisciplinary group with nutritionists should advise the patient on their diet and necessary vitamin supplements. Normally you should take iron (especially in cases of women of childbearing age), calcium (especially in patients over 40 years) and some vitamin supplements, but through a varied diet will ingest most of the minerals and vitamins necessary for the body.


For more information consult the specialist in General Surgery .


*Translated with Google translator. We apologize for any imperfection

By Dr. Alfredo Alonso Poza

Dr. Alonso Poza is a prominent General Surgeon with more than two decades of experience. He is Doctor Cum Laude from the University of Valladolid, specialist in Laparoscopic, Colorectal and Obesity Surgery.

Since 2007 he is the Head of the General Surgery and Digestive Diseases Service of the Hospital del Sureste de Madrid in Arganda del Rey. He is a Member of the Spanish Society of Surgery of Obesity and author of numerous articles for national and international scientific journals.

*Translated with Google translator. We apologize for any imperfection

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