The failure to offer obese patients weight-loss surgery is costing the wider economy hundreds of millions of pounds every year, leading surgeons have said.
The financial toll of unemployment, housing and incapacity benefit, hospital admissions and prescriptions is increasing every year but could be cut dramatically if people were given surgery, they added.
The direct cost of obesity and related illnesses to the NHS is £4.3 billion a year and millions more to the wider economy in England.
The report, from the Royal College of Surgeons, National Obesity Forum and health firms Allergan and Covidien, said thousands of patients are missing out on surgery, pushing costs higher.
NHS trusts are not following guidelines set down by the National Institute for Health and Clinical Excellence (Nice), which say people with a body mass index (BMI) over 40, or between 35 and 40 if they also have a condition such as diabetes or high blood pressure, are eligible for surgery.
Experts calculated that if 5% of eligible patients were given weight-loss surgery, the gain to the economy within three years would be £382 million.
If 25% were granted surgery, the gain within three years would be £1.3 billion.
The Government could also expect savings in benefit payments of £35 million to £150 million as people head back to work, the study said.
If Nice guidance was followed, direct NHS cost savings would be around £56 million a year.
Taking these figures into account, experts argued that weight-loss surgery effectively pays for itself within a year.