Sleeve gastrectomy: How much weight can I expect to lose?

Written by: Mr Ahmed Hamouda
Edited by: Carlota Pano

A sleeve gastrectomy is a bariatric surgical procedure that can help to induce weight loss by reducing the size of the stomach.


Here, Mr Ahmed Hamouda, renowned consultant upper GI and bariatric surgeon, provides an expert insight into a sleeve gastrectomy. He explains what the procedure entails exactly, what are the risks of the operation, and how much weight loss can patients expect, among other important points.



How does a sleeve gastrectomy compare to other weight loss surgeries?


A sleeve gastrectomy is the most common and popular option available at the moment in terms of weight loss interventions. The procedure sits between a gastric bypass and a gastric band in terms of its efficacy, as well as its long-term effects. 


During the operation, 3/4 of the stomach is removed using keyhole (laparoscopic) surgery under general anaesthetic. This reduces the size of the stomach, thereby restricting how much food can be eaten. At the same time, the procedure also decreases the levels of ghrelin in the gut, which is one of the hormones responsible for appetite and cravings. This dampens down appetite to a large extent.


How much weight loss can patients expect from a sleeve gastrectomy?


This figure is calculated using a patient’s individual BMI, which is the ratio of weight to height. A BMI above 25 is defined as being overweight, while a BMI of 30 and above is defined as obesity.


A BMI of 25 is defined as healthy. This means that if a patient’s BMI is 45, then that patient is carrying 20 BMI points of extra weight. Patients who undergo and benefit from a sleeve gastrectomy correctly can expect to lose approximately 65 to 75 per cent of this extra weight.


What are the short and long-term risks of a sleeve gastrectomy?


A sleeve gastrectomy is a major surgical operation that uses general anaesthetic. Even though the operation is performed via keyhole surgery, there is a risk of conversion to open surgery due to complications.


In addition, there are also other risks involved, like bleeding and infection, that can occur in the short-term. In the longer term, there is a risk of weight regain, with patients putting the weight back on again after the procedure.


Moreover, patients who undergo any type of weight loss surgery - it does not need to be a sleeve gastrectomy, specifically - can also experience hair loss three or four months after surgery. However, instead of going bald, patients will find that there is a bit of hair loss when brushing or combing their hair. In most cases, the hair will regain its normal function and strength eight to 12 months after surgery.


Patients who wish to undergo a sleeve gastrectomy should also know that they will be required to take multivitamin and mineral supplements for life. This is done to make up for any deficiencies in nutrition that may develop as a result of eating less food.


Can you explain the procedure and recovery process for a sleeve gastrectomy?


Patients will be pre-assessed in the weeks before surgery. This will include doing blood tests. In some cases, patients will also meet a dietician, a nutritionist and possibly a psychologist as well, in preparation for surgery.


Patients should not eat or drink anything prior to surgery. General anaesthetic will also be given before the intervention begins, so patients should be asleep and relaxed for the duration of the whole sleeve gastrectomy.


During the procedure, I will insert several keyhole instruments as well as a camera through 4 to 5cm incisions in the upper abdomen. This will be done not only to create space inside of the stomach to perform the sleeve gastrectomy, but also to remove 3/4 of the stomach, leaving only 1/4 of the stomach behind. As a result, the size of the stomach will be reduced. This will restrict the amount of food that can be eaten, and also decrease the levels of ghrelin that were found in the 3/4 portion of the stomach that was removed.


In terms of recovery, patients will usually stay in hospital for one to two nights maximum following surgery. There are no tubes or drains left behind after surgery, so patients should be able to start their diet straight away. This diet will be liquid-only for at least two weeks before progressing to soft foods for another two weeks and then finally, to solid foods after that.


After a sleeve gastrectomy, patients can start walking straight away. Long walks are no problem at all.


However, I would not recommend driving for at least two weeks after the procedure. I would also recommend to not engage in gym work, heavy lifting or any form of exercise during the first weeks following surgery until the body settles down.


What lifestyle changes may be necessary after a sleeve gastrectomy?


Lifestyle changes after a sleeve gastrectomy are very important, because this operation needs to be looked at as a tool for weight loss rather than a magic wand. A sleeve gastrectomy only works if patients commit to changing the way that they are eating and what they are eating. Although portion sizes are much smaller, calories have to be looked at as well, so a healthy diet needs to be followed after surgery.


As well as this, there also has to be a commitment to increasing activity and being much more energetic in general. This is because if patients do not exercise, or do not take exercise as part of a change in lifestyle and a new beginning, then they will not drop the maximum amount of weight that can be lost with a sleeve gastrectomy. As a result, they will either lose less weight on average, or even, put on a bit of weight back.


For this reason, it is extremely important to look at a sleeve gastrectomy as a surgical tool to changing oneself, changing one’s lifestyle, and changing one’s behaviours in the long run.



Mr Ahmed Hamouda is a highly respected and skilled consultant upper GI and bariatric surgeon with over 30 years’ experience.

If you are considering a sleeve gastrectomy and wish to discuss your options with an expert, do not hesitate to visit Mr Hamouda’s Top Doctors profile today.

By Mr Ahmed Hamouda

Mr Ahmed Hamouda is a highly respected consultant upper GI and bariatric surgeon based in Kent. He is renowned for his expertise in bariatric surgery, as well as gallbladder and abdominal hernia surgery. He also specialises in reflux surgery and balloon endoscopy procedures.

Mr Hamouda qualified in medicine at Ain Shams University, Egypt in 1992 before pursuing further training within a residency programme in general surgery. He later relocated to the UK to undertake specialty training, including an esteemed year-long laparoscopic biliary fellowship in Glasgow, where he gained invaluable expertise in minimally-invasive cholecystectomy and bile duct exploration procedures. Following the completion of his surgery specialty training, he also completed a six-month advanced bariatric fellowship in a renowned Centre for Excellence in Bariatric Surgery. For over ten years, Mr Hamouda served as an upper GI consultant at Maidstone and Tunbridge Wells NHS Trust and is now based at Nuffield Health Tunbridge Wells Hospital, where he is an integral part of the bariatric service, bringing with him his wealth of expertise and experience in endoscopic sleeve, gastric band and gastric bypass procedures, amongst many others. He also sees private patients at the KIMS Hospital in Maidstone, the Benenden Hospital in Cranbrook and Sevenoaks Medical Centre.

Throughout his esteemed career, Mr Hamouda has been involved in the education of medical students and his academic excellence earned him a university lectureship post shortly after graduating in medicine. Additionally, he has published a number of academic papers which appear in peer-reviewed journals. He regularly participates in important meetings within his field and is a member of a number of key professional bodies, including the British Obesity and Metabolic Surgery Society, the Association of Laparoscopic Surgeons and the European Association of Endoscopic Surgery. He is also director and lead bariatric surgeon at Weight Loss Surgery Kent.

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