Weight Loss Surgery
Gastric Bypass
Everything you need to know about gastric bypass weight loss surgery, from experts in bariatric surgery.
Medically reviewed by Prof Rishi Singhal MBBS, MRCS, FRCS, MD
- Last Reviewed 18/03/2026
Gastric Bypass Overview
The Gastric Bypass is a long-established weight loss procedure. Over 30 years of safe and effective weight loss outcomes and significant health benefits. The procedure is carried out laparoscopically via key-hole incisions in the abdomen.
- Average Length of Stay
- Operation Duration
- Anaesthesia
- Recovery Duration
- Excess Weight Loss
- BMI Eligibility
- 2 Nights
- 45 - 60 Minutes
- General Anaesthesia
- 14 Days
- 60 - 70%
- 40+
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Average Length of Stay
2 Nights -
Operation Duration
45 - 60 Minutes -
Anaesthesia
General Anaesthesia -
Recovery Duration
14 Days -
Excess Weight Loss
60 - 70% -
BMI Eligibility
40+
What are the Health Benefits of Having Gastric Bypass Surgery?
90%
of type II diabetes are cured (in remission)
80%
will have improvement in cholesterol levels
90%
will have improvement in reflux symptoms
85-90%
of patients with hypertension reduce or stop medication
90%
of patients with Polycystic ovary syndrome have restored fertility
80%
With Liver Disease will have complete resolution of liver disease
85%
of patients who use a continuous positive airway pressure machine will be able to stop
More Benefits
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.**
- Mobility improves dramatically and joint pain decreases
- There are improvements in mood and self-esteem, and overall quality of life
- Perhaps the biggest benefit of all is that people live longer after bypass surgery!
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.
What is a Gastric Bypass?
Gastric bypass surgery is the most powerful form of weight loss surgery for people living with obesity. In short, gastric bypass surgery reduces the size of your stomach and redirects the digestive tract. Having a gastric bypass is the best weight loss surgery for patients with a high body mass index (BMI). On average most patients will lose weight of up to 80% of their excess weight after gastric bypass surgery. Alongside the weight loss, the gastric bypass can help reverse serious weight-related health conditions such as type 2 diabetes and PCOS.
The Gastric Bypass Helps People Lose Weight By
- The gastric bypass reduces the capacity of the stomach from full-sized into a small pouch, meaning you don’t need to eat as much to feel full
- The pouch gets connected to the small intestine, bypassing the rest of your stomach and fewer calories are then absorbed.
UK’s Most Comprehensive Aftercare Package
The importance of great aftercare is often underestimated when it comes to gastric bypass. Most patients enjoy excellent weight loss in the first year or two but some weight regain is quite common after a few years. This can be reduced by adopting the correct dietary and exercise habits in the first couple of years after surgery.
Healthier Weight gastric bypass patients benefit from 5 years post-operative care including medical monitoring via regular follow-ups with our specialist bariatric nurses and surgeon reviews if required
Gastric Bypass Procedure
The procedure is carried out laparoscopically via key-hole incisions in the abdomen.
- 45min - 1hr Operation
- 2 night hospital stay
- 90 day return to theatre cover
Dedicated Support
Our range of nutritionists, Health Coaches and support team are here to help every step of the way
- 5 year comprehensive aftercare
- 24/7 Live App Support
- Group Health Coach sessions
- Lifelong support and advice
- Private Facebook support group
Weight Loss Tools
Videos and live classes on diet, fitness, behaviour change, body composition scales and activity tracker
- WI-FI Scales
- Personalised App
- Healthier Weight Starter Kit
- Food diary and trackers
- 5 day BariOne sample
Gastric Bypass Operation
The simplest way to describe bypass surgery is to say that the stomach and bowel are ‘re-plumbed’ so that the food you eat goes into a reduced stomach before passing directly into the bowel a little further down the bowel than was the case before. The bypass works in two ways. Firstly, by reducing the size of the stomach and so restricting the amount of food that can be eaten. We usually reduce the stomach’s capacity by as much as 90-95%. On this page, we give a technical breakdown of how the procedure is done.
Am I Eligible for the Gastric Bypass?
The ideal candidates for gastric bypass surgery are those who have a body mass index (BMI) of 40 or higher, or a BMI of 35 or higher with significant obesity-related health conditions like type 2 diabetes, high blood pressure, or sleep apnea. These individuals should have also made sincere efforts to lose weight through conventional methods such as diet and exercise, without achieving sustainable results.
Compared to NHS eligibility
In the United Kingdom, the National Health Service (NHS) provides gastric bypass surgery for eligible individuals. To access this procedure through the NHS, patients typically need a referral from their primary care physician. The referral is usually made to a specialist bariatric service, where further assessments and evaluations are conducted to determine the appropriateness of the surgery. The decision to offer gastric bypass surgery on the NHS is based on various factors, including the patient’s BMI, their obesity-related health conditions, and the impact of these conditions on their overall well-being. The waiting times for surgery can vary depending on the local NHS policies and resource availability.
Private Eligibility
At Healthier Weight, we specialise in bariatrics. We offer gastric bypass surgery for individuals seeking a dedicated and personalised approach to their weight loss journey. Our criteria for eligibility focus primarily on a BMI of 40 or higher, with no upper BMI limit, as we specialise exclusively in weight loss procedures. We understand that obesity affects individuals differently, and our team of experienced surgeons, dieticians, and support staff are dedicated to evaluating your unique circumstances. We prioritise your individual goals, health conditions, readiness for the procedure, and long-term commitment to ensure the best outcomes.
How Much Weight Will I Lose with the Gastric Bypass?
Of course, the main benefit people are seeking when they have 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 the bypass.
Typically, we expect 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, 70-80% 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. Our bariatric aftercare team is vital to helping you learn and embed the skills needed to maximise and maintain your weight loss (see before and after photos and stories from gastric bypass patients here).
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
Nik’s Transformation
Lost 16 Stone
“The gastric bypass was the only way to get rid of the demons”
Georgina’s Transformation
Lost 7 Stone
“The mutual support both in that group and in the Healthier Weight aftercare team has been amazing”
Kerry’s Transformation
Lost 8 Stone
“Healthier Weight was the only provider that made her feel comfortable”.
Gastric Bypass Finance
-
Flexible Terms
Humm offers interest-free, flexible payment plans to help you split the cost of your purchase into smaller instalments. -
Competitive Rates
Borrow at a highly competitive rate of 17.99% over a period up to 5 years -
Quick & Easy
Immediate decision in principle within 2-3 minutes -
Customer Service
Humm is a truly responsible lender with customers at the heart. If you would like to talk to us in person about your finance options please call us on 0800 3134618
Damson Parkway, Solihull, B91 2PP
Priory Road, Birmingham, B5 7UG
13-14 Fitzroy Square, London W1T 6AH
Chalybeate Cl, Southampton SO16 6UY
Clinics offering the Gastric Bypass
Gastric Bypass Common FAQs
How long will I be off work after a gastric bypass?
This depends upon what you do for a living, but if you have a sedentary occupation you can generally expect to be back at work about 2 weeks after gastric bypass, after which time the wounds should have healed and you will be feeling more comfortable. If you have a physically demanding job involving lifting etc, you may need a little longer. The bowel and stomach inside your abdomen will be healed in around 6-8 weeks, so during this period it is important that you follow the nutritional guidelines as closely as you can.
Why can't I get a gastric bypass abroad?
Your long term success with your procedure is dependent on high quality aftercare. Anyone who has had weight loss surgery will tell you this is crucial. All too frequently, overseas surgery packages have no aftercare.
In the UK surgeon outcomes are monitored closely. There is a duty of candour and transparency. In many overseas countries the same standards do not apply.
We have seen many botched procedures from overseas that come with limited aftercare and warranties. You won’t receive any support from any serious problems that arise post-op, and you will ultimately go onto the NHS waiting list for your procedure to be put right.
Will I have scars after gastric bypass surgery?
Generally there is minimal scarring with a gastric bypass. The operating ports are placed in the abdomen through 5 narrow (0.5 cm) incisions which are sutured and/or glued and will normally heal in about 10-14 days. The scars should fade gradually. Some individuals have a greater tendency to form keloid which may result in thicker and more prominent scars.
What can you eat with a gastric bypass?
You may eat most foods that don’t cause you discomfort. However, because you can only eat small amounts, it is important to include foods rich in protein but low in fat and sugar. We encourage you to eat vegetables, fruit, wholegrains, lean meat and fish. You will be provided with detailed nutritional information following your gastric bypass surgery.
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Patient Care Coordinator
My role is to support you with starting your weight-loss journey with Healthier Weight. During our conversation, we will explore the choices available to you and address any questions and concerns you may have. When you feel ready to move forward, we will arrange a free, no obligation consultation with one of our surgeons.
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All content on this page is reviewed by a multi-disciplinary team led by Prof Rishi Singhal.