Gastric sleeve and gastric bypass are today the most widespread bariatric surgeries, due to their efficacy, safety and comfort for the patient.

Both are performed laparoscopically, with a quick recovery and a short hospital stay. The way to reintroduce food after both surgeries will be similar and is done progressively in terms of food consistency, increasing it every 2 weeks approximately.

During the first two weeks, an exclusively liquid diet should be followed, containing between 600 and 800 kilocalories and 60 grams of protein per day. To achieve these goals it is usually necessary to take commercial diet preparations in the form of shakes.

The following two weeks should be followed a shredded diet , containing at least 60 g of protein. It usually consists of purees or porridges, usually homemade, and which include eggs, fish or white meat.

Later, they go on to a soft diet, in which they eat foods of a soft consistency or crushed with a fork, maintaining a similar protein ratio.

Two weeks later you can generally switch to a diet of normal consistency, although this does not mean a free diet. It is very important to chew all food slowly and completely , trying to pause after each bite. Calorie intake should be controlled, which will range between 800 and 1200 Kcal.

Protein intake is very important throughout the process, and it should be at least 1.2 g for every kilo of ideal weight (our doctor will inform us of this), and always greater than 60 g per day. In addition, the percentage of fat should be less than 30% of the diet.

In general, in gastric sleeve the transition from liquid to solid food is slower than in gastric bypass. On the other hand, in gastric bypass, the intake of foods rich in sugars can cause what is known as dumping syndrome , with abdominal pain, nausea and general ill feeling, so this type of food should be avoided.

A series of general recommendations that can be applied to both interventions would be: make small but frequent intakesthroughout the day (5 or 6 servings), as well as drinking plenty of fluids such as water, fat-free broths or sugar-free infusions, but avoiding them 30 minutes before or after meals. Commercial soft drinks and juices should be avoided, as well as alcoholic beverages. You should control the amount of oil used for stews, and avoid fried and battered, although there is the option of using “air fryers” that do not need oil. Eggs, fish, chicken, turkey and shellfish are generally well tolerated, and should be progressively introduced into the puree, mashed and solid phases. Red meat and pork should be introduced later, as they are usually less tolerated. Finally, the bread should be wholemeal, as well as the pasta and rice that are used as a side.

Regarding nutritional status, the pre-existence of a deficit of one or more micronutrients (vitamins or minerals) is common in obese patients before starting their weight loss process. In addition, the risk of deficiencies increases after surgery, mainly due to the decrease in the amount of food eaten and the decrease in the absorption capacity of vitamins and minerals.

We must bear in mind that the gastric sleeve is a purely restrictive technique, while the bypass is a mixed technique, that is, with a restriction component and a malabsorption component. For this reason, the type of nutritional supplementation will be different in each technique.

Gastric sleeve

It is based on reducing the amount of food we eat, but it does not alter the physiology of digestion and absorption, so it is very rare that there are nutritional deficits.

It is usually enough to take a generic multivitamin preparation on a daily basis, especially during the first year, coinciding with the greatest weight loss. Occasionally, you can choose to take calcium and vitamin D, and in women of childbearing age add oral iron, which your doctor will regulate based on the analytical controls performed.

Gastric bypass

In this surgery there are changes in the intestinal anatomy that can cause micronutrient deficiencies , so it is very important to take nutritional supplements and perform a closer analytical control.

As in the gastric sleeve, a generic multivitamin preparation should be taken daily, which is usually sufficient to maintain the levels of folic acid, thiamine, and fat-soluble vitamins (A, E, K).

Unlike gastric sleeve, iron deficiency is very common , mainly in women of childbearing age, so oral supplements should be taken routinely.

Vitamin B12 deficiency is common and can be prevented by taking a daily supplement or injection every month or every 6 months.

To avoid the loss of bone mass, it is also necessary to take supplements that contain calcium and vitamin D in the same tablet.

Although these are generic recommendations that apply to most patients, it is essential to go to the check-ups prescribed by your doctor , who will monitor the adequate weight loss and nutritional status.