Please note – this is NOT a complete list of potential risks of surgery.  Please consult with your doctor before undergoing surgery.


Surgery works for some, but it is not for everybody and is generally an option of last resort.  There are a range of medical reasons not to be getting this type of surgery that you will learn from your doctor as no surgery is without risks.  All surgery carries the potential for complications like mild to severe infections, scars, bleeding and complications related to the anaesthetic.  

To date, the long-term safety of lap banding and the Roux en Y bypass has been documented, however evidence on long-term safety is lacking for the sleeve gastrectomy. Each procedure has its own advantages and disadvantages. When we look at the data in general for these 3 procedures we see some common threads for risks and benefits.  

For all risks it changes depending on the surgeon, so you will have to ask them for their specific records. However, when it comes to risks we can look at those occurring less than 30 days and over 30 days and here are some general principles.

Looking at a few different studies we can see data involving over 60,000 bariatric patients.  The risk of death within the 30 days following bariatric surgery averages 0.13 to 0.3%, or approximately 1-3 out of 1,000 patients.  And about 4/100 people have at least one major side effect, with those who had poor health before the operation were at a higher risk of these problems.

For risks over 30 days, this is surprisingly hard to find and the exact rates depend on the complication.  The most common complications long term are deficiencies in vitamins and minerals by reducing nutrient intake or by causing reduced absorption from the intestine.  These occurred in up to 78% for vitamin D and 40% for other minerals like zinc and iron.  Other common complications included reflux in ~25% of people, hernias in 20% of people, and issues like diarrhoea, constipation and food intolerances.  So it is crucial these are discussed in detail with your doctor.

However, the benefits are quite significant.  Depending on the specific type of surgery the weight loss could be around 50-60% of your excess weight loss for ~85% of people having it over 2 years.  That means 15% will not achieve this but still have some weight loss.  Note that is excess weight loss, not total.  So if your weight is 120kg or 260lbs, then your healthy weight is 70kg or about 150 lbs, and hence you are 50kg or 110 lbs of excess body weight.  Hence you could lose 60% of that excess body weight, which in this example is 30kg or about 70 lbs, which would take you down to ~90kg or ~190 lbs.  The American Society for Metabolic and Bariatric Surgery also report that cancer mortality is reduced by 60%, death in association with diabetes is reduced by more than 90% and that from heart disease by more than 50%.  It is uncertain whether any given bariatric procedure is more effective than another in controlling comorbidities.  So there are some major benefits to the procedures as well.

What about the long-term weight loss benefits and are there failure rates?  There have been some concerns reported by major journals like the Cochrane review, which is very reputable, about the limited high-quality evidence supporting its use and the lack of long-term data. So the exact failure rate is hard to give because of this.  Though studies suggest about 4/10 people who had the operation failed to lose 50% of their excess body weight after 5 years.