Overweight people in Bath and North East Somerset may be forced to wait three months before having operations.
From now on, clinically obese patients will be supported to lose weight before an operation is considered.
Patients who smoke will be helped to give up before they receive an operation.
Studies show a healthy lifestyle reduces the risk of complications during and after surgery.
It can also help speed up the recovery process once the operation is complete.
The changes will affect patients with a body mass index (BMI) of 30 or above.
Dr Ruth Grabham, Medical Director at the Bath and North East Somerset Clinical Commissioning Group and local GP said "We want to make sure patients are in the best possible health before they have an operation.
“Stopping smoking and achieving a healthy weight before routine surgery helps limit avoidable complications, improves surgical outcomes, aids the recovery process and can improve the patient’s wellbeing as they get better faster. Their stay in hospital may also be shorter. There are also long-term health benefits for those who don’t smoke and are a healthy weight.”