Obesity is one of the chronic diseases with the greatest impact on health worldwide. According to the World Health Organisation (WHO), more than 1 billion people across the globe suffer from obesity, and these figures continue to rise. When conventional treatments (diet, exercise and medication) are insufficient to achieve significant and sustained weight loss, bariatric surgery presents itself as an effective option backed by scientific evidence.

However, there is still a great deal of uncertainty and concern surrounding this procedure. Who is eligible for surgery? Is it safe? What changes does it involve in daily life?

Here we will try to address all your questions and concerns to help make the decision-making process easier. Even so, we recommend booking an appointment with your specialist, as we will be able to guide you on which options are best suited to your individual circumstances.

 

What is bariatric surgery?

Bariatric surgery encompasses a range of surgical procedures designed to produce significant and lasting weight loss in people living with severe obesity. The technique works by reducing the capacity of the stomach, thereby limiting food intake.

The most commonly performed procedures at present are:

Sleeve gastrectomy (gastric sleeve): approximately 75–80% of the stomach is removed, creating a small-capacity tube. It is the most widely performed technique globally, owing to its efficacy and relatively lower technical complexity.

Roux-en-Y gastric bypass: a small gastric pouch is created and connected directly to the small intestine, reducing both intake and absorption. It yields excellent results, particularly in patients with associated type 2 diabetes.

Adjustable gastric band: this technique is less commonly used today due to its lower long-term efficacy and higher rate of late complications.

Biliopancreatic diversion: a more complex procedure with a significant malabsorptive component, reserved for cases of extreme morbid obesity.

Beyond weight loss, bariatric surgery has been shown to produce remission or significant improvement of obesity-related conditions such as type 2 diabetes, arterial hypertension, sleep apnoea and dyslipidaemia, thereby improving the patient’s overall life expectancy and quality of life.

 

Who is eligible for bariatric surgery?

Patient selection is a rigorous medical process that must be carried out within a specialist unit. This is not a cosmetic procedure, but a medical intervention indicated for specific clinical profiles. The general criteria for indication, as agreed upon by the leading scientific societies, include:

• Body mass index (BMI) equal to or greater than 40 kg/m², regardless of the presence of comorbidities.
• BMI between 35 and 40 kg/m² with at least one serious obesity-related comorbidity, such as type 2 diabetes, arterial hypertension, obstructive sleep apnoea syndrome, cardiovascular disease or severe osteoarthritis.
• In certain selected cases, and in accordance with the most recent guidelines, BMI between 30 and 35 kg/m² in patients with poorly controlled type 2 diabetes.
• Demonstrated failure of conservative treatments (diet, exercise, pharmacological therapy) maintained over a reasonable period under medical supervision.
• Age between 18 and 65 years, although selected cases outside this range may be considered.
• Genuine commitment from the patient to adopt the lifestyle changes and long-term follow-up that the surgery requires.

It is equally important to identify those who are not suitable candidates, including patients with untreated active eating disorders, severe inflammatory bowel disease, advanced liver disease, uncontrolled severe psychiatric conditions, or active alcohol or drug use, among others.

 

The pre-surgical process: a comprehensive assessment

Prior to the procedure, the patient undergoes a thorough multidisciplinary evaluation, which includes:

• Full medical assessment: detailed blood tests, cardiorespiratory function, abdominal ultrasound and other investigations as required on a case-by-case basis.
• Nutritional assessment: to address any pre-existing deficiencies and begin education on the dietary changes required after surgery.
• Psychological evaluation: essential for identifying eating behaviour patterns, realistic expectations and capacity for treatment adherence.
• Consultation with the surgeon: detailed explanation of the recommended technique, associated risks and expected outcomes.

This process is not a bureaucratic formality — it is the foundation upon which the long-term success of the intervention is built.

 

What to expect after bariatric surgery?

Bariatric surgery is not a quick fix, but rather the beginning of a transformative process that requires an active commitment. The following are the most relevant aspects of the post-operative period and expected progress:

Immediate post-operative period (first few weeks)
Hospital admission typically lasts between 2 and 4 days. The diet begins as liquids and progresses gradually until solid food, adapted to the patient’s new anatomy, is reintroduced over a period of 4 to 8 weeks. Fatigue, abdominal discomfort and changes in bowel habits are common during the first few weeks.

Weight loss
Weight loss is most rapid during the first 12 to 18 months. In general terms, patients may lose between 60% and 80% of their excess body weight. The sleeve gastrectomy and gastric bypass are the techniques that yield the best results in this regard.

Improvement of associated conditions
One of the most notable outcomes is the remission or significant improvement of associated diseases. Type 2 diabetes goes into remission in more than 60–80% of patients following gastric bypass, in many cases even before significant weight loss has occurred, which suggests an independent metabolic mechanism of action.

Follow-up and supplementation
After surgery, regular medical follow-up is essential. The absorption of certain micronutrients — such as vitamin B12, iron, calcium and vitamin D — may be compromised, which means nutritional supplementation is usually necessary. Periodic blood tests allow any deficiencies to be identified and corrected promptly.

Lifestyle changes
Surgery is a tool, but habits are the driving force. Patients must commit to a balanced diet adapted to their new circumstances, regular physical exercise, and ongoing medical and psychological follow-up over the long term. Those who embrace these changes achieve more lasting results and a significantly improved quality of life.

 

Bariatric surgery, when correctly indicated and performed in a specialist setting with appropriate follow-up, is one of the medical interventions with the greatest demonstrated positive impact on the patient’s overall health. It does not merely transform weight — it has the potential to transform quality of life.

If you are living with obesity and would like to arrange a medical appointment to explore your weight loss options, at Dr Christian Leyva’s practice we carry out a comprehensive assessment of your specific clinical situation, answer all your questions and support you at every stage of the process — from the initial consultation through to post-surgical follow-up.

Do not wait for obesity to keep limiting your life. Book your appointment with Dr Christian Leyva today and find out whether bariatric surgery could be the solution you have been looking for.