The NHS would regret the cost of limiting treatment for obesity, a group of surgeons said today.
According to a report, patients with severe obesity face premature death, disease and disability which could be prevented or eliminated by surgery.
Research by the National Bariatric Surgery Registry (NBSR) found obesity surgery treats a range of life-threatening diseases, including achieving an 86% reduction in the number of patients with type 2 diabetes.
Surgeons suggest the figures demonstrate the cost-effectiveness of early weight-loss treatment.
Data from more than 8,700 operations carried out in the NHS and private sector showed around two thirds of severely obese patients have three or more associated diseases by the time they reach surgery.
Meanwhile a third have high blood pressure, over a quarter have diabetes and nearly a fifth have high cholesterol.
Following surgery, patients who had a 12-month follow-up examination lost some 58% of excess weight. And there was improvement on all associated diseases.
After two years, 86% of those affected by diabetes prior to surgery showed no indication of the disease.
The NBSR said the cost of bariatric surgery - which includes gastric bypasses and gastric bands - is recouped within three years as obesity-associated costs are eliminated.
Bariatric surgeon Alberic Fiennes, chairman of the NBSR data committee, said: "This data shows that not only is UK bariatric surgery safe, but it successfully treats a whole range of diseases - including the rapid resolution of diabetes - yet commissioners continue to ignore the facts.
"An approach that limits treatment to a fraction of those who would benefit is one which the NHS will rue in years to come as these patients become an unsustainable burden on the health service.
"Prevention strategy alone has proved ineffective. There are at least two generations of morbidly obese patients who are now presenting with diabetes, stroke, heart disease and cancer for whom preventative measures are utterly irrelevant.
"The numbers are increasing - these people need to be treated."
David Stout, NHS Confederation Primary Care Trust (PCT) Network director, said: "It is right that surgeons should get together to start measuring the efficacy of the work they do and set the standards for services to be improved in future.
"While surgery will always be an important part of dealing with increasing obesity, the most cost effective solution is to make sure that people do not get to the stage of needing surgery in the first place.
"The National Institute for Health and Clinical Excellence (Nice) provides PCTs, and the GP consortia that will replace them, with guidance on which patients should be considered for weight-loss surgery as part of a wider strategy to address obesity.
"They also have to have public health strategies in place which encourage a healthier diet and lifestyle.
"PCTs need to balance their priorities across a wide range of services, taking into account Nice guidance in the context of local needs. But it is important that all commissioners are transparent in their decision-making."
A Department of Health spokesman said: "England has some of the highest rates of obesity in Europe - concerted effort is needed to tackle this."
Government was encouraging people to make simple changes, such as eating more fruit and vegetables, cutting down on fatty foods and being more active, the spokesman said.
"Bariatric surgery should only be considered as a last resort once weight loss schemes and exercise programmes have been tried."