Many overweight people in England are having surgery withheld unless they lose weight - even though some patients need treatment in order to get into shape, leading medics have warned.
Policies to restrict surgery based on a person's weight could affect a "significant proportion" of the population, the Royal College of Surgeons (RCS) said.
Blanket bans that deny or delay patients' access to surgery are "wrong", said RCS president Clare Marx.
The RCS said people who are overweight and smokers are becoming "soft targets" for NHS savings after its latest report found that more than one in three areas of England restrict surgery to some of these patients.
The College examined information on policies from clinical commissioning groups (CCGs) around England and discovered several "worrying" restrictions on access to surgery.
It looked into protocols for hip and knee replacements, hernia surgery, tonsil removal and general policies covering planned procedures.
The RCS found that 34% of the 200 CCGs have one or more policies on body mass index (BMI) level or smoking status which stop overweight patients or smokers being referred for routine surgery.
Many regions were contravening national clinical guidance by denying or delaying routine surgery to patients - such as hip and knee replacements, it said.
Almost a third of CCGs have one or more mandatory policies on BMI level, stopping overweight or obese patients being referred for routine surgery, the RCS found.
And 22% of the regional health bodies are placing mandatory weight thresholds on referral to hip and knee replacement surgery - a rise from when they were last polled in 2014 when the figure stood at 13%.
Meanwhile 12% of CCGs require patients to stop smoking before they can access one or more routine surgical procedures.
Miss Marx said: "Blanket bans that deny or delay patients' access to surgery are wrong.
"NHS surgical treatment should be based on clinical guidance and patients should be dealt with on a case by case basis. In some instances a patient might need surgery in order to help them to do exercise and lose weight.
"While it is difficult to categorically prove such policies are aimed at saving money, it is unlikely to be a coincidence that many financially challenged CCGs are restricting access to surgery.
"Our worry is that smokers and overweight patients are becoming soft targets for NHS savings.
"There is no clinical guidance from the National Institute for Health and Care Excellence, the Royal College of Surgeons, and other surgical associations to support mandatory bans for routine surgery on the basis of whether patients smoke or are overweight."
Tim Wilton, president of the British Orthopaedic Association, added: "There is no clinical, or value for money, justification for refusing to fund hip or knee replacements based on BMI or smoker status. Good outcomes can be achieved for patients regardless of whether they smoke or are obese, even at BMIs of over 50, and these surgeries are highly cost effective.
"Hard-and-fast rules also undermine the NHS's ability to involve patients in decisions about their own care, and are a distraction from the task at hand: making sure patients receive the best possible advice and care, to enable them to make the best possible decisions for their health - including losing weight and stopping smoking where appropriate. These comorbidity issues are best dealt with by appropriate informed consent and not by management dictat."
The news comes after health officials in Birmingham came under fire over plans to ration surgery and treatments.
Six Birmingham region CCGs were accused of taking guidance out of context or misusing it in an attempt to restrict services.
Under the CCGs' plans, only patients that meet a strict criteria will be allowed to receive 45 procedures, with GPs having to apply for specific funding for those with "exceptional clinical need".
Tam Fry, from the National Obesity Forum, said: "CCGs are rationing hip and bariatric surgery because they now have to pay for it themselves.
"The RCS is absolutely correct and, furthermore, the GPs' action is both unethical and a false economy.
"Bariatric surgery pays for itself within two years and the very fat are sitting ducks for more expensive and long-term conditions.
"Not only is their weight bearing down on their hips and knees but they may acquire type 2 diabetes, heart disease, cancers and stroke.
"In addition it is quite stupid to erect barriers to surgery which, if carried out quickly, could save the NHS money and the patients a lot of grief "