It is, without a doubt, the first question my patients ask during their consultation. And it makes perfect sense: you've spent years fighting overweight or obesity, you've tried diets, exercise routines, treatments, and now you're considering taking a more definitive step. It's completely normal to want to know what you can expect.
The honest answer is that it depends, but within a well-documented and fairly predictable range. Here I explain everything you need to know.
What does the evidence say?
Studies consistently show that patients who undergo bariatric surgery can lose between 60% and 85% of their excess weight. If you have, for example, 40 kilograms above your ideal weight, we would be talking about 24 to 34 kilograms lost. And most importantly: that weight loss is maintained over time, as long as it is accompanied by lifestyle changes.
What is the pace of weight loss like?
The first six months show the greatest decrease; many patients lose more than half of their total weight during this period. In the second half of the year the pace slows down, and between the first year and a year and a half it stabilizes at the final result. The body doesn't drop weight all at once; it does the work progressively and safely.
What factors determine the outcome?
The type of procedure is one of them: gastric bypass tends to produce somewhat greater weight loss than the gastric sleeve, although each case requires an individualized evaluation. The surgeon is the one who determines which technique is most appropriate for your needs and your health.
Your starting weight also plays a role, as does the presence of associated conditions such as diabetes, and above all your commitment to dietary changes and physical activity after surgery.
Surgery is not the destination; it's the starting point. It is an extraordinarily effective tool for your body to begin responding in a way it couldn't before. But you are a fundamental part of the outcome.
What happens in the long term?
It's normal to regain some weight over the years, especially if healthy habits are not maintained. However, even with partial regain, operated patients rarely return to their initial weight, and the health benefits -- remission of type 2 diabetes, improvement of hypertension, resolution of sleep apnea -- are maintained significantly.
Rigorous studies show that after bariatric surgery, the risk of death from obesity-related diseases is reduced by up to 89%. Weight is not just a cosmetic issue; it's a matter of life.
How do I know if I'm a candidate?
The general criteria include having a Body Mass Index of 40 or higher, or a BMI of 35 with associated conditions such as diabetes, hypertension, or sleep apnea. But every patient is different, and a personalized consultation is the only way to know for certain.
- BMI of 40 or higher
- BMI of 35 or higher with associated conditions (diabetes, hypertension, sleep apnea)
- Having tried other weight loss methods without sustained success
In my practice, the first appointment includes a thorough review of your medical history, a physical examination, and an open, pressure-free conversation about whether surgery is the right decision for you. My job is not to convince you to have surgery: it's to give you all the information you need so that you can decide with clarity.