Weight loss (bariatric) surgery: types, eligibility and risks

NICE Clinical Knowledge Summaries describe obesity as a condition associated with a higher risk of type 2 diabetes, coronary heart disease, high blood pressure, stroke, depression, some cancers, obstructive sleep apnoea and breathlessness, and say that most complications of obesity can be reduced by weight loss. They state that multicomponent interventions, meaning behaviour change on activity, eating and diet quality, are the treatment of choice, with drug treatment considered as an addition for some adults. Bariatric surgery sits further along that pathway, for people in whom other approaches have not been enough or whose health risks are high.

CKS says bariatric surgery is the option of choice for adults with a BMI of more than 50 when other interventions have not been effective, and is also recommended as an option for some adults with a BMI of 40 or more, or between 35 and 40 with other significant diseases that could improve with weight loss, such as type 2 diabetes, high blood pressure or severe mobility problems.

The NHS gives three conditions: a BMI of 40 or more, or a BMI between 35 and 40 with a condition that might improve if you lost weight (it names high blood pressure, diabetes, arthritis, breathing problems and asthma); and an agreement to make healthy lifestyle changes and attend regular check-ups after surgery. For people from the family backgrounds listed in the key facts above, CKS says lower BMI thresholds are used as a practical measure, and the NHS says surgery may be considered below a BMI of 40.

The NHS says availability differs between areas, and notes that you can also pay for surgery privately but that this can be expensive, so ask any provider for an itemised quote that covers the operation, follow-up and any complication care.

The NHS says gastric bypass, gastric band and gastrectomy are all done by a surgeon using keyhole surgery under general anaesthetic, while endoscopic sleeve gastroplasty is done by passing a flexible tube through the mouth to the stomach.

The NHS lists blood clots (deep vein thrombosis, or clots that travel to the lungs), a stomach leak in the days or weeks after gastric bypass or sleeve gastrectomy that can cause serious infection, a gastric band slipping out of place, wound infection, a blocked gut, gallstones that can form with fast weight loss, and excess skin. To reduce the risk of a blockage it suggests cutting food into small chunks, chewing thoroughly and not drinking during meals.

Excess skin surgery such as a tummy tuck is usually considered cosmetic and is not always available on the NHS, so ask your GP what your local area provides.

The NHS says to call 999 or go to A&E if you have difficulty breathing with leg pain and swelling, chest pains with leg pain and swelling, severe tummy pain, non-stop bleeding from your bottom, vomiting blood or poo, or sick that looks like coffee grounds or soil. It advises an urgent GP appointment or NHS 111 for leg redness, tenderness or swelling that is not improving, a high temperature or feeling hot, cold or shivery, a fast heartbeat, tummy pain, fast breathing, difficulty swallowing or regular vomiting, and a GP visit for wound pain, red hot swollen skin or pus.

The sources reviewed here describe the procedures and their risks but do not rank them or give weight-loss figures, so those are questions for your surgical team. Sensible questions are: which procedure suits my BMI and conditions, what happens to my diet afterwards, which complications are most likely with this operation, whether it can be reversed (the NHS says endoscopic sleeve gastroplasty may be reversible because nothing is cut, stapled or removed), and how long follow-up lasts.

Because the NHS makes lifestyle change and attendance at check-ups a condition of access, plan to take part in a structured programme before and after surgery, covering diet, activity and psychological support. CKS describes weight management programmes as including behaviour change strategies on activity, eating behaviour, diet quality and energy intake.

NHS access depends on meeting the criteria above and on what is available in your area. Private bariatric surgery is a separate route that the NHS says can be expensive. If you consider it, ask whether the surgeon works within a team that includes dietitians and psychologists, what aftercare is included and who treats complications, including if you become ill while travelling.