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Gastric Bypass Surgery

Gastric Bypass Surgery in London

Gastric Bypass Surgery in London

Gastric bypass surgery (most commonly the Roux-en-Y gastric bypass) is a weight loss procedure that works by making your stomach smaller and by bypassing part of your digestive system. This means that you won't be able to eat as much and your body will absorb less of the food you do eat. The procedure is performed as keyhole surgery. You will be under general anaesthesia so that you sleep through the operation. It generally takes between one and three hours.

The average patient can expect to lose about 60-70% of your extra weight after this procedure. Although the gastric bypass surgery can make it a bit easier to lose weight, you will only achieve results if you stick to the diet plan.

Laparoscopic Gastric Bypass Surgery Costs

* Please note that these are guide prices based on you being fit for the procedure - quotes may vary according to individual requirements and discuss this with team following your consultation.

The hospitals where Mr Agrawal works have 0% finance options to allow you to spread the operation costs completely interest-free over extended periods.

To our knowledge, these package prices were correct as on 5 th April, 2021. However, please check for up-to-date prices with the relevant hospital you are interested in for your surgery

You need to know

You need to know

What risks are associated with the gastric bypass?

Gastric bypass surgery is a very safe procedure. However, your doctor will explain the risks in detail so that you can provide informed consent. It is important to understand the potential adverse effects and complications, even if the chance of experiencing these problems is small.


Sometimes the operation can produce unwanted side-effects alongside the beneficial effects of the surgery. These side-effects are usually temporary. The most common side-effects of gastric bypass surgery are swelling, bruising and pain around the surgical wound. You may also feel a bit sick or vomit after your meals as you get used to the change in your stomach size. You can reduce the risk of this by limiting the amount you eat. If you eat too many sugary foods you can get an unpleasant sensation, called "dumping", which may make you feel sick or faint, or give you diarrhoea. You should drink plenty of fluids until the feelings have passed, and you should also reduce the amount of sugary foods you eat. Some of the side effects can last longer. One of the effects of gastric bypass surgery is that it will be harder for your body to absorb nutrients. This, along with your more restricted diet, could put you at risk of deficiencies in certain vitamins and minerals, particularly calcium and iron. You might need nutritional supplements to stay healthy.


Complications are problems that occur either when you are in surgery or soon afterwards. Serious complications are rare after gastric bypass surgery, but they do affect some patients.

Like any serious operation requiring general anaesthesia, the gastric bypass procedure comes with a risk of certain complications. You might experience a bad response to the drugs and anaesthetic, you might lose more blood than expected, or you could develop blood clots that might cause problems such as a pulmonary embolism or DVT. The risks of having surgery will be higher if you have any medical problems such as cardiovascular disease.

Among the complications that can develop after gastric bypass surgery are:

  • Infection – can often be treated or prevented with antibiotics.

  • Damage to abdominal organs – may require surgical repair.

  • Anastomotic leak (join) - the point where your intestine is re-joined to your stomach pouch could start leaking in the days after surgery. Another operation might be needed to fix the problem.

  • Anastomotic stricture or anastomotic ulceration (join) – the point where your intestine is re-joined to your stomach pouch could become too narrow. Ulcers could also develop after surgery. You might need to have an endoscopy to repair it, or another operation.

  • Internal herniation and adhesion problems – you may need further surgery for it.

  • Gallstones – rapid weight loss can sometimes cause gallstones to form. Gallstones can be very painful and sometimes need to be removed surgically.

  • Failing to reach your target weight – some people do not lose enough weight after the procedure. Some people lose weight but then regain it later.

If a problem does arise during the operation, it may not be possible to complete the procedure laparoscopically. The surgeon will need to create a larger incision to perform open surgery. However, this will only be done if it is absolutely necessary.

The precise risks of a gastric bypass are different for everyone. However, the overall risk of complications is usually about 5-10%. The risk of a fatal complication is much smaller, at 0.5%.

You should try to lose weight through diet and exercise before committing to weight loss surgery. You may also want to try medication first. If you decide that surgery is right for you, there are alternatives to the gastric bypass. You might want to consider a gastric band or gastric sleeve.

- Greater and faster weight loss than with the other kinds of weight loss surgery.

- An immediate remission of type 2 diabetes and improvement in blood pressure within days of having the operation in up to 80% of cases.

Several laparoscopic bariatric procedures are available to help with weight loss. You can click here for a chart comparing gastric bypass surgery with the other kinds of weight loss surgery available in London.

It is important to learn as much as you can about gastric bypass surgery so that you can decide if it is right for you. You should discuss the surgery, its risks, and the benefits with your doctor, who will help with your decision. The bypass procedure is a serious operation that will change the way food moves through your digestive system. You should also consider whether this form of bariatric surgery will actually make it easier for you to achieve your weight loss goals. The gastric bypass can produce the fastest and greatest weight loss, so it could be a good option if you have a lot of weight to lose or if you have to lose weight urgently for medical reasons. The bypass can help by restricting the amount you can eat, so it may benefit you if you often feel empty and dissatisfied at the end of your meals when you're dieting. It can also make sugary foods less palatable, so it could be particularly helpful if you have a sweet tooth. The bypass will also affect your ability to absorb nutrients from your food. Although this can help with your weight loss, it can also make it difficult to get the vitamins and nutrients you need. You must be prepared to take supplements and be very careful about your diet if you go ahead with this surgery.

Most patients spend two or three days recovering in hospital after having gastric bypass surgery. It will take two or three weeks to recover completely from a gastric bypass.

The changes made during gastric bypass surgery are usually permanent. However, in exceptional circumstances it's possible to fully or partly reverse it, for example, in an emergency or if you experience severe side-effects or complications from the operation.

A full reversal of gastric bypass surgery requires another operation of the same, or greater scale, with the same, or greater, risks than your original operation. Because of this, you will usually only be considered for the reversal operation if you experience long-term side-effects or complications. A full reversal of your gastric bypass operation will usually mean that you regain any weight you have lost.

An alternative to a full reversal which is sometimes performed is an operation to reduce the amount of your bowel that was originally bypassed. This won't mean that you will be able to eat more, but it will allow you to absorb more of your food.

Success Stories


Cristin Casey’s Gastric Bypass Story

Watch our valued client Cristin Casey taking about her experience having consultation from Mr Sanjay Agrawal at The London Obesity Group clinic in London.

Before / After

Before / After




Case Studies

Case studies

Book A Free Telephone Consulting

Book A Free Telephone Consulting

Please provide us with a few information or call us on 07876 618424 and a member of our friendly team will be happy to help with your request.

Clinic Locations

Clinic Locations


    Harley Street, London

    27 Harley Street, London W1G 9QP


    The London Independent Hospital

    Stepney Green, London E1 4NL


    Spire London East Hospital

    Ilford, Essex IG4 5PZ


    The Holly Hospital

    Buckhurst Hill, Essex IG9 5HX


    Rivers Hospital

    Harlow, Hertfordshire CM21 0HH


    Nuffield Health

    Brentwood Essex CM15 8EH

Visiting Hospitals

Visiting Hospitals

  • Nuffield Hospital
  • Spire London East Hospital
  • The London Independent Hospital
  • Rivers Hospital
  • The Holly