Bariatric surgery brings together several techniques to treat obesity when diet and exercise have not worked. The three most common are sleeve gastrectomy (gastric sleeve), gastric bypass and duodenal switch (biliopancreatic diversion). They differ in how they reduce the stomach and in whether or not they limit nutrient absorption. The right technique is not the same for everyone: it is decided by the medical team after assessing your BMI, your health and your goals.
Obesity affects millions of people and, when diet and exercise are not enough, surgery is an option for those with a very high body mass index (BMI). There are several types of bariatric surgery, each with its own advantages and considerations. At the Bariatric surgery in Girona unit of Medics Integral Salut, the indication for each technique is established individually, after a complete medical consultation.
The goal of any bariatric technique is the same: to help you lose weight and improve long-term health by modifying the digestive system. What changes is how each procedure achieves it. Let's go through the techniques one by one and then a table that compares them at a glance.
What bariatric surgery is and what it is for
It is a surgical procedure that modifies the digestive system to reduce the amount of food that can be eaten and, in some techniques, the amount of nutrients the body absorbs. Beyond weight, it aims to improve quality of life and reduce obesity-related diseases such as type 2 diabetes, hypertension, sleep apnoea or heart disease. In many cases it helps to regain mobility and to control or improve these conditions.
Types of bariatric surgery
Vertical gastrectomy (gastric sleeve)
It is one of the most common techniques. Approximately 80% of the stomach is removed to create a smaller, sleeve- or tube-shaped stomach with a capacity of about 60 to 150 ml. By reducing the size of the stomach, you eat less and feel full sooner and for longer. It also decreases the production of ghrelin, the hormone that stimulates appetite. It is an effective technique for long-term weight loss and is usually associated with fewer long-term complications than bypass.
Gastric bypass
It consists of creating a small pouch at the top of the stomach (about 15 to 30 ml) and connecting it directly to the small intestine. The lower section of the stomach and the upper part of the intestine are left intact but are not used for digestion. This reduces both the amount of food that can be eaten and the absorption of nutrients (restrictive and malabsorptive component). It is one of the most effective procedures for long-term weight loss and can improve or even help put into remission problems such as type 2 diabetes and hypertension.
Duodenal switch (biliopancreatic diversion)
It combines the removal of a portion of the stomach with rerouting of the gastrointestinal tract: a small gastric pouch is created and connected to the small intestine, bypassing a large part of the intestine and the duodenum. This markedly reduces the nutrients and calories absorbed, leading to significant weight loss. It is a less common and more complex technique than the previous ones, reserved for selected cases of morbid obesity or serious obesity-related health problems.
Vertical gastrectomy vs. gastric bypass vs. duodenal switch
Comparative summary of the three most common techniques. It is a guide only: the final choice depends on the individual medical consultation.
| Sleeve gastrectomy | Gastric bypass | Duodenal crossing | |
|---|---|---|---|
| How it acts | Restrictive: reduces the stomach | Restrictiva + malabsortiva | Restrictive + malabsorptive (greater) |
| What is modified | About 80 % of the stomach is removed (sleeve shape) | Small gastric pouch connected to the small intestine | Gastric pouch + extended bypass of the intestine and duodenum |
| Stomach capacity | ~60–150 ml | ~15–30 ml | Small gastric pouch |
| Efecto hormonal | Reduces ghrelin (appetite) | Changes in digestive hormones | Changes in digestive hormones |
| Complexity | Media | Media-alta | High (less common) |
| Perfil habitual | A very common and versatile technique | Very effective, useful with type 2 diabetes | Selected cases of morbid obesity |
Criteria for indicating bariatric surgery
The selection starts from a thorough assessment of each patient's needs and goals. As a guide, the following are considered:
- BMI: it is considered with a BMI of 40 or more, or 35 or more with an obesity-related condition (type 2 diabetes, hypertension…).
- Weight-loss history: having tried to lose weight with diet and exercise without managing to maintain results.
- Age: usually between 18 and 65.
- Realistic expectations: weight loss is not automatic; it requires commitment and long-term lifestyle changes.
Before operating, a medical and mental health evaluation is carried out: the team assesses your general health, your ability to tolerate surgery and recovery, and discusses risks, benefits and alternatives.
Recovery and results
After surgery there is a recovery period that can last several weeks, with an initial liquid or soft diet so that the stomach can adapt and heal, as well as possible medication adjustments and follow-up with a specialized team. Results vary depending on the technique and the patient: studies describe losses of between 50 % and 80 % of excess weight in the first two years, along with health improvements such as remission of type 2 diabetes, better control of blood pressure and cholesterol, or improvement of sleep apnea. Not all patients achieve the same loss.
Possible risks and side effects
Like any surgery, it carries possible complications that the medical team assesses in each case, including infection, bleeding, nausea and vomiting, diarrhea or intestinal obstruction. It is not a magic solution: to maintain the results it is essential to follow a healthy diet with a Nutritionist in Girona and to exercise regularly.
What a gastric sleeve is and what a gastric bypass is
These are the two best-known bariatric techniques and the ones that raise the most questions, so it is worth explaining them separately before comparing them.
What a gastric sleeve is
Gastric sleeve is the popular name for sleeve gastrectomy. It consists of removing approximately 80 % of the stomach to leave it in the shape of a narrow tube or “sleeve”, with a capacity of about 60 to 150 ml. It is a restrictive technique: it does not touch the intestine or alter nutrient absorption, but reduces the volume of the stomach so that the person feels full with much less food. In addition, by removing the part of the stomach that produces most ghrelin (the appetite hormone), the feeling of hunger decreases. It is considered a versatile, widely used procedure, and in general has fewer long-term complications than the bypass.
What is gastric bypass
Gastric bypass creates a small pouch in the upper part of the stomach (about 15 to 30 ml) and connects it directly to the small intestine, bypassing (hence “bypass”) a portion of the stomach and intestine. It combines two mechanisms: it is restrictive (you eat less) and malabsorptive (fewer nutrients and calories are absorbed). It is one of the most effective procedures for long-term weight loss and usually has a very favourable effect on associated diseases such as type 2 diabetes and hypertension, although it requires stricter nutritional monitoring because of the risk of vitamin deficiencies.
Difference between gastric sleeve and bypass: which is better and which is less invasive?
The essential difference is that the gastric sleeve only reduces the stomach (restrictive), whereas the bypass also changes the path of the intestine to limit absorption (restrictive + malabsorptive). Several frequently asked questions arise from this:
- Which is less invasive? In general, the gastric sleeve is considered technically somewhat simpler and less complex, since it does not reconnect the intestine. The bypass is a more elaborate procedure.
- Which one leads to more weight loss? The bypass usually achieves somewhat greater weight loss and better control of type 2 diabetes, but in exchange for more demanding nutritional follow-up.
- Which is better? There is no single answer: there is no "best" technique for everyone. The most suitable one depends on BMI, associated conditions, habits and each person's preferences, and the medical team makes the decision with you after the consultation.
Choosing between one and the other is not a matter of fashion or of what worked for an acquaintance, but of individual medical indication. That is why the comparison in the table above is only a guide: it helps you understand the differences, not to self-diagnose.
What is dumping syndrome
Dumping syndrome (or “rapid emptying”) is an effect that can appear mainly after a gastric bypass, when food —especially food rich in sugars— passes too quickly from the stomach to the small intestine. It can cause symptoms such as nausea, sweating, palpitations, dizziness, abdominal pain or diarrhoea shortly after eating (early dumping) or episodes of hypoglycaemia somewhat later (late dumping). Although it sounds alarming, it has a positive side: it works as a learning mechanism that “penalises” the consumption of sweets and helps consolidate healthier habits. It is managed mainly with dietary guidelines (small, frequent meals, avoiding simple sugars, separating liquids from solids) indicated by the nutrition team.
Which insurance or social security covers bariatric surgery?
Bariatric surgery is recognised as a treatment for obesity when there is a medical indication, and in the public system (social security) it can be performed in cases that meet specific clinical criteria —usually a high BMI with associated diseases and after a multidisciplinary assessment—, although it often involves waiting lists and strict requirements. In the private sector and with health insurance, coverage varies greatly from one policy to another: some include it under certain conditions, waiting periods or requirements, and others exclude it because they consider it linked to obesity. The practical recommendation is to check the specific conditions with your insurer and confirm at the medical consultation whether you meet the indication criteria. As with any surgery, the final decision depends on an individual evaluation.
How much bariatric surgery costs
There is no single price for bariatric surgery: it depends on the technique (the sleeve, the bypass and the duodenal switch do not cost the same), the complexity of the case, the preliminary tests, the team and the subsequent medical and nutritional follow-up, which is a fundamental part of the treatment. That is why a fixed figure says little if it does not detail what it includes. A realistic quote is settled after the consultation, once the technique indicated for your case has been defined. If you need to organise payment, the clinic offers financing options that you can look into.
How to lose weight without surgery: alternatives
Surgery is not the only path, nor the first step for everyone. In many cases of moderate overweight or obesity, there are less invasive alternatives that may be the best option, especially when the BMI does not meet the surgical criteria:
- Gastric balloon: a temporary device placed in the stomach to reduce appetite and make weight loss easier, without surgery. You can learn about the options in the 12-month gastric balloon unit, the 6-month balloon unit and the Elipse ingestible balloon unit.
- MEGA Method (endosleeve): a reduction of the stomach by endoscopy, without open surgery. More information in the endosleeve unit.
- Medical and nutritional treatment: Dietetics and Nutrition plans with follow-up and, in selected cases and under medical prescription, weight-loss medication.
Choosing well is key: “more aggressive” is not always better. You can read more about how to select the right treatment for weight loss. The ideal option is defined by the medical team according to your situation.
Am I a candidate for bariatric surgery?
As a guide, you may be a candidate if:
- You have a BMI of 40 or more, or 35 or more with an obesity-related condition.
- You have tried to lose weight with diet and exercise without lasting success.
- You are willing to commit to long-term lifestyle changes and to follow-up.
- You are in general health that allows for surgery and recovery.
The final indication is always established by the medical team after an individual consultation. Are you a candidate for bariatric surgery? →
Resolve your case with the medical team
Initial no-obligation medical and nutritional assessment in Girona.
Related video
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Frequently asked questions
What is the difference between sleeve gastrectomy and gastric bypass?
What is a gastric sleeve?
What BMI is required for bariatric surgery?
How much weight is lost after surgery?
Does bariatric surgery cure diabetes?
How is the recovery?
What is a gastric bypass?
What is the difference between a gastric sleeve and a bypass, and which is less invasive?
What is dumping syndrome?
Do social security or insurance cover bariatric surgery?
How much does bariatric surgery cost?
How can you lose weight without surgery?
Treatments and related units
Explore the treatments for Overweight and Obesity Unit and other areas of the clinic. Filter by area:
Bariatric surgery
Vertical gastrectomy, bypass, and duodenal switch for indicated cases.
Related articles
We serve patients from all over the province of Girona
Our clinic is located in the centre of Girona (Plaça Poeta Marquina, 3) and we regularly see patients from the city and the entire surrounding area and the Costa Brava. If you are coming from further afield, we coordinate appointments to group assessments and tests on the same day.
Plaça Poeta Marquina, 3, 17002 Girona · easy access from the AP-7 and N-II · How to get there and opening times
Medical review Content produced by the Medics Integral Salut medical team and reviewed by the Overweight and Obesity Unit.
Sources and references: Spanish Society of Obesity Surgery (SECO) · Spanish Society for the Study of Obesity (SEEDO).