Gastric bypass surgery: how it is performed, side effects and results

Written by: Mr Alistair Sharples
Edited by: Conor Lynch

Gastric bypass surgery is a surgical procedure that involves the rearranging of one’s small intestines and the dividing of one’s stomach into a small upper pouch and a larger lower pouch. The aim of the surgery is to then connect the small intestine to both these small upper and large lower pouches.


Here to provide an expert, comprehensive overview of this surgical procedure is highly experienced leading consultant surgeon, Mr Alistair Sharples.

What does a gastric bypass surgery involve?

A gastric bypass operation works in a number of ways. Firstly, the stomach will need to be shrunk down significantly which inevitably results in some restriction as to how much food can be eaten.


Secondly, the bypass part of the procedure bypasses a large segment of the first part of the small bowel which reduces absorption of calories.


The final stage, and probably the most important, is the rearranging of the anatomy. This leads to significant changes in the hormonal responses to eating, which subsequently results in the production of much larger amounts of certain hormones. As a direct result, patients notice improvements in insulin control, diabetes management as well as hunger control. 


How much weight can someone lose with gastric bypass surgery? 

This will obviously vary significantly depending on the individual. However, as a rough guide, the majority of patients will lose approximately 3/4 pounds of their excess weight


How long can the positive effects of gastric bypass surgery last for?

All bariatric procedures will lose some of their effectiveness over time. However, if combined with sensible lifestyle changes such as an improved diet and greater amounts of exercise, then there is no reason that the positive effects should not last for the duration of one’s life.


Is this a safe procedure?

Evidence shows that bariatric surgery is extremely safe. Complication rates for this sort of surgery are significantly lower than for many other types of commonly performed operations, such as gallbladder surgery, hernia surgery or hip and knee replacements.


Most patients will only need to be in hospital for two nights maximum, and should fully recover from the procedure within a couple of weeks. Complications do occasionally occur of course, as with any operation, but these are unusual. 


What are the main side effects?

Bariatric surgery is life changing, and thus, should be considered very carefully before making any final decision. The operation permanently changes the anatomy and the way patients interact with food.


For most patients, this is a very positive change, but if not adequately prepared preoperatively, this can be a struggle. All patients will need to take multivitamins on a lifelong basis following surgery and will need to commit to various long-term follow-up and annual blood tests.


There is a risk of developing nutritional deficiencies due to the effects of the surgery if not adequately followed up on. Occasionally, patients my develop chronic pain, nausea or swallowing difficulties after surgery.


However, for the vast majority of patients meeting the criteria for bariatric surgery, the benefits significantly outweigh any complications. 


Is gastric bypass surgery still going ahead during the pandemic?

Yes, bariatric surgery is still being performed during the pandemic. 


Mr Alistair Sharples is a highly qualified, leading consultant surgeon who specialises in bariatric surgery but to name a few. If you are considering undergoing a gastric bypass surgery and would like to consult with an expert who can guide you in the right direction, you can visit Mr Sharples’ Top Doctors profile to book a consultation with him.

By Mr Alistair Sharples

Mr Alistair Sharples is a leading consultant surgeon who sees patients at the renowned Infinity Surgery Clinic. Mr Sharples completed his undergraduate in Manchester and surgical training throughout the West Midlands.

Mr Sharples practices in all aspects of bariatric surgery, benign upper gastrointestinal surgery and general surgery, including a high volume of revisional work. He often carries out upper GI (Food pipe and stomach) surgery and bariatric (weight loss) surgery. He also treats hiatal hernias and performs general and keyhole surgery including treatment of gall stones and hernias. 

He has Fellowship training in upper gastrointestinal and bariatric surgery, having completed fellowships both within Canada and the UK. In addition, Mr Sharples has completed a post-graduate certificate in Medical Education and a MSc in Trauma Science.

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