Media playback is unsupported on your device Media caption Keith Billington says people do not recognise him since his weight-loss surgery

Nearly 40% of under-25s who have weight-loss surgery in the UK are classified as super-obese, according to new figures.

Surgeons say this is evidence of "a clear failure of strategies to prevent weight gain in young people".

Overall, more patients are having weight-loss surgery and, on average, they are getting more obese and more ill by the time of surgery.

A leading bariatric surgeon said severe obesity threatens to bankrupt the NHS.

The figures are contained in a report, from the National Bariatric Surgery Registry, which includes information on more than 18,000 weight-loss operations in 137 UK hospitals between 2010 and 2013.

The operations were made up of 9,526 gastric bypass procedures, 4,705 gastric band operations and 3,797 sleeve gastrectomy operations.

The aim of bariatric surgery is to improve the overall health of very obese patients, for whom dieting and lifestyle changes have not made any difference.

The report concludes that bariatric surgery is both safe and effective.

As in all branches of medicine, prevention is better than cure but this report clearly demonstrates that when required, bariatric surgery is effective and safe Sir Bruce Keogh, NHS medical director

'Super-obese' young

It says there are too many young people reaching levels of severe obesity who need weight-loss surgery.

Between 2010 and 2013, 550 young people under the age of 25 had bariatric surgery of some kind, 62 of whom were under 18.

Nearly 40% of these young men and women were already classified as super-obese (with a BMI of 50 or more), the report says, adding: "It is a reflection on society's failings that these patients had already gained sufficient weight to be broadly comparable to patients who are much older."

After analysing procedures for all age groups, the report found more men were being treated with bariatric surgery - up from 16% of all weight-loss operations in 2006 to 26% in 2013.

At the time of surgery, male and female patients were - on average - nearly twice the weight they should be for their height, with an average BMI of 48.8.

About three-quarters of the men and women treated could not climb three flights of stairs without resting and, on average, patients had more health complications and were more ill at the time of their operation than in previous years.

Excess weight loss

But the good news, surgeons say, is that after surgery, more than half of patients (56%) could manage three flights without resting and the amount of time they spent recovering in hospital decreased, despite the rise in more complex weight-loss operations.

The figures also show that, on average, one year after an operation, patients had lost nearly 60% of their excess weight and a majority of those with weight-related type 2 diabetes were no longer showing symptoms.

Mr Richard Welbourn, consultant surgeon and chairman of the National Bariatric Surgery Registry, said severe and complex obesity was a condition "which threatened to bankrupt the NHS".

He said the data showed there were great benefits to be gained from bariatric surgery.

"In particular, the effect on diabetes has important implications for the NHS. Bariatric surgery cost-effectively improves the health of obese patients."

In the report, Sir Bruce Keogh, medical director of the NHS, said: "Obesity and bariatric surgery are rapidly rising up the NHS agenda as a consequence of social and lifestyle choices.

"As in all branches of medicine, prevention is better than cure, but this report clearly demonstrates that when required, bariatric surgery is effective and safe."

What is bariatric surgery?

Bariatric surgery, also known as weight-loss surgery, is used as a last resort to treat people who are dangerously obese and carrying an excessive amount of body fat.

This type of surgery is available on the NHS only to treat people with potentially life-threatening obesity when other treatments have not worked.

Around 8,000 people a year currently receive the treatment.

The two most common types of weight loss surgery are:

Gastric band, where a band is used to reduce the size of the stomach so a smaller amount of food is required to make someone feel full

Gastric bypass, where the digestive system is re-routed past most of the stomach so less food is digested to make someone feel full

NHS Choices

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