Mini Gastric Bypass | Weight Loss Surgery

Everything you need to know about mini gastric bypass weight loss surgery, from experts in bariatrics.

Gastric bypass

By Mr Rishi Singhal MBBS, MRCS, FRCS, MD

Last review: 11/07/2022. All content on this page is reviewed by a multi-disciplinary team lead by Mr Rishi Singhal.

What is a mini gastric bypass?

The mini gastric bypass is an attractive alternative to the traditional Roux-en-Y gastric bypass. In fact, if you are considering a bypass or gastric sleeve then it’s worth considering the mini bypass too. On this page, you’ll find all you need to know about the ‘mini’, but the three key features are:

  • It offers similar weight loss and health benefits to the Roux and the sleeve.
  • It’s the simpler and quicker of the two bypass procedures.
  • The way the procedure is done means that the risk of an internal hernia does not apply.

The mini bypass is now established in the NHS and we expect ‘mini’ numbers to increase rapidly. It offers a number of benefits over the traditional ‘roux-en-y’ gastric bypass, some of which are significant. Here are the benefits:

  • Weight loss outcomes are marginally better with the mini than the roux-en-y
  • The bowel is not cut through and re-attached to the stomach, and there is only one anastomosis (join between the stomach and bowel). Less cutting means less risk and a faster recovery
  • The mini is a quicker procedure
  • The risk of an internal hernia (the most worrisome risk for bypass patients, reduces to near zero with the mini)
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As with the standard Roux-en-Y gastric bypass, the mini gastric bypass works both by restricting the amount of food that can be eaten at any one time, and by altering gut hormones involved in appetite control. Mini gastric bypass (MGB) as we know it today was developed by Dr Robert Rutledge in 1997. Since then tens of thousands of procedures have been done and MGB is growing in popularity in many countries around the world. For many patients it provides a quicker and more effective alternative to the traditional bypass. Most patients considering gastric sleeve should also consider MGB too.

  • Patients appear to experience a little more nutritional deficiency in the very long term. That said, we think new surgical techniques, with a shorter limb of 150cm, largely overcomes this. 
  • Early studies showed an increase in acid reflux. The later publications don’t show this, and… 
  • There is relatively little data when compared to the Roux.  Set against the benefits these disadvantages seem very modest. 

The main difference between the standard Roux-en-Y gastric bypass procedure and the mini gastric bypass can be seen by comparing the two diagrams. You can see that in the case of the mini bypass there is only one anastamosis (join between stomach and bowel), whereas in the standard Roux-en-Y bypass there are two; an upper and lower. Because of this the mini gastric bypass can be done in less time than Roux-en-Y.

Am I eligible?

The eligibility criteria for Mini is broadly the same as for Roux en y gastric bypass. We consider patients eligible for ‘Mini’ when they have a BMI above 40. You will also need to have tried other methods to manage your weight and your weight will be having a negative impact on your day to day life. Our decisions about eligibility are based on the published data for each procedure and the general NICE guidance published by the Department of Health.


You can view those guidelines here. Decisions about your eligibility are always discussed with you face to face at your consultation when we’ll discuss the pros and cons and make sure you understand which procedure is best for you personally. In exceptional cases we will consider Mini down to a BMI of 35, but never lower.

The mini gastric bypass operation

In the first part of mini gastric bypass surgery, the stomach is divided, and a small tube of stomach created. The food that is eaten goes into this small stomach. This is the restrictive part of the procedure and means that only a very small amount of food can be eaten at any one time.


Next, the surgeon brings up a loop of bowel (about 150cm long) and joins this to the lower part of the new smaller stomach (the join is called the “anastamosis”). In this way food passes from the small stomach into the small bowel and here it meets the digestive juices which have been produced in the bigger stomach. In effect, therefore, about 150cm of small bowel has been bypassed before the calories and nutrients of the food you eat is absorbed in the bowel. By consuming fewer calories you will lose weight*.

The Mini bypass will become a mainstream procedure in the treatment of obesity in the period ahead. It gives excellent results and a number of benefits when compared to the Roux. Both have a role to play and which is preferable will vary form patient to patient. Those looking at the sleeve should also consider the Mini. There are very good reasons, especially when it comes to managing leaks, that favour the Mini.

How much weight will I lose?

Of course, the main benefit people are seeking when they have mini bypass surgery is to lose weight. There are other significant benefits however, especially where improvements in health are concerned. Those people who are managing health problems associated with their weight can expect significant improvements after bypass.

Typically, as with the standard gastric bypass procedure we expect mini gastric bypass patients to lose 60-70% of their excess weight over a 2-year period, and most of this weight is lost in the first year after surgery*. You will see from our case studies that some people lose all their excess weight. To compensate there will be some who lose a little less. For this reason, 60-70% is a reasonable expectation. 

Weight loss results will differ from person to person and your results, especially in the long term, will depend on how well you are able to adapt your lifestyle and eating habits. 

Weight loss example

  • A 5ft 6in person weighing 17st (240lbs / 109kgs) has an ideal weight of about 11st (154lbs / 70kgs)
  • They are carrying excess weight therefore of 86lbs (240lbs actual weight minus 154lbs ideal weight)
  • 70% of 86lbs is around 60lbs
  • So, this person could expect to lose (on average) about 60lbs (27kgs).

Scientific evidence suggests that most gastric bypass patients who comply with the follow-up requirements, including nutritional recommendations, do very well, and see great long-term results*. Moreover, compared with obese individuals who have not had surgery, gastric bypass patients have a much lower risk of premature death and disability.

*JAMA. 2012 Jan 4;307(1):56-65. doi: 10.1001/jama.2011.1914. Bariatric surgery and long-term cardiovascular events

Gastric bypass success stories

Health benefits of weight loss surgery?

Turning to the health benefits bypass patients can expect, it’s a long list and the improvements are usually very significant. In many cases people see a complete resolution of their symptoms for the problem they are managing.  Here are some of the more common weight related health problems and the benefit people can expect.**

As specialists in weight loss surgery we are familiar with all the health issues associated with obesity. It is also our duty to inform all our patients of the risks and potential complications of gastric bypass surgery, you can view these here. If you have specific health question, please do contact our team and we’ll be pleased to discuss them with you.

Video: How my health improved after weight loss surgery

**Buchwald H et al. Bariatric surgery: a systematic review and meta-analysis. JAMA. 2004 Oct 13;292(14):1724-37.

Mini gastric bypass cost and finance

The price of the Mini gastric bypass is the same as for the Roux en Y Gastric Bypass. This is because the theatre time and stay in the hospital are broadly the same. Your package will include a comprehensive aftercare and support programme. In order to obtain a personalised quotation and to see the finance options that are available, please request a quotation.

We provide formal personalised quotations so that enquirers are clear on what is included in our package. Several payment plans are available if you would like to spread payments over a period of time.


The importance of aftercare and support is often underestimated with the mini gastric bypass. Often people think the procedure is so powerful that they lose weight without too much effort, especially in the early months. However, over time the power of bypass will subside, and it will be the diet, eating and exercise changes that you have made in the years after your surgery that will help you maintain your weight loss.

Our team is here to see you in clinic and to provide the support you need for enduring success.

With this in mind, we have developed an aftercare and support package that we consider to be the most comprehensive of its type in the UK.

Our aftercare package has been developed to provide everything you need for success.

Mr Rishi Singhal MBBS, MRCS, FRCS, MD

Mr Rishi Singhal MBBS, MRCS, FRCS, MD

Mr Singhal is an expert bariatric surgeon based in the West Midlands and also Medical Director at Healthier Weight

For the first time in a very long time I have something to look forward to – seeing the new me adapt to my new life. I took control of my life. In the last year I’ve changed my job and I’ve found love. I would recommend this to anyone.

Call our specialist team today on
0800 3134618 
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