Overall, more patients are having weight-loss surgery and, on average, they are getting more obese and more ill by the time of surgery.
The figures are contained in the 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.
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 shows there are 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."
The operations featured in the report were made up of 9,526 gastric bypass procedures, 4,705 gastric band operations and 3,797 sleeve gastrectomy operations. The report also concludes that bariatric surgery is both safe and effective.
Prevention is better than cure
Sir Bruce Keogh, medical director of the NHS, added: "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."
According to the findings 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.