The NHS would regret the cost of limiting treatment for obesity, a group of surgeons has said.
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 some 58% of excess weight was lost by patients who had a 12-month follow up examination, 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."
A Department of Health spokesman said: "Often, just losing a small amount of weight can reduce the risk of problems such as type 2 diabetes. The local NHS should have weight management services in place to meet the needs of their population. Bariatric surgery should only be considered as a last resort once weight loss schemes and exercise programmes have been tried."