Routine operations, including for hip and knee replacements, will be delayed for patients with a BMI of over 35 and smokers, who will be offered weight loss and stop smoking programmes.
The measures have been introduced by East Riding CCG, which has denied that it is about saving money, saying it is to "encourage and empower patients to take greater responsibility for their lifestyle choices."
Paula South, Director of Quality & Governance/Lead Nurse at East Riding CCG, admitted the change would see "less activity" in the four hospitals, Hull Royal Infirmary, Castle Hill Hospital, Goole Hospital, and patients from Bridlington who are sent to Scarborough Hospital, affected for six months.
Ms South said: "This is not about money. This is not about cutting waiting lists. There will be a pause in the amount of surgery going through the hospitals.
"In terms of saving money in a whole year it won't make any difference."
The measures however have been condemned by the Royal College of Surgeons, which warned that other groups of patients could face rationing.
Its president Clare Marx said the ban was the "wrong approach and frankly shocking".
She said decisions about whether to treat a patient should be based on their need and "not arbitrary criteria about weight and smoking status".
She added: "If smokers and patients are hit this time, where will the rationing decisions fall next?"
Those denied surgery will be offered a weight management service run by East Riding Council at sessions at leisure centres in the area.
Patients can pay to go to Weight Watchers or Slimming World, or not take any formal support at all.
The CCG said patients who didn't reach their target weight or stopped smoking after six months, would still be put forward for surgery.
Restrictions for routine surgery have also been imposed in other parts of North Yorkshire and the West Riding as part of measures designed to save cash.
Rotherham has also imposed restrictions on hip and knee replacements where one of the criterias allowing surgery is that patients have a BMI of less than 35, and are suffering "severe persistent pain."