Fat patients are less likely to die after heart surgery, a study suggests.

The research throws NHS rationing – where obese patients have been told to slim down before operations – into doubt.

Experts analysed data for the number of people who died in hospital following heart surgery, according to their weight.The results showed that people who were a healthy weight were almost twice as likely to die as those who were obese or overweight, while those who were underweight had the highest risk of death.

The study, published in the journal Circulation, included 401,227 adults who had undergone heart surgery between 2002 and 2013.

Overall, 11,511 patients died. Some 4.4% people of a normal weight died, compared to just 2.8% who were overweight and 2.7% who were obese. Meanwhile, 8.5% people who were underweight died.

Overweight-boy

People of a healthy weight twice as likely to die than those who are obese or overweight (Photo: Getty)

The University of Leicester researchers took into account factors that could influence the results, such as people’s age or whether they had other health conditions.

But the study still found that being fat – including suffering complications of obesity such as high blood pressure, diabetes and artery disease – seemed to offer protection,

The researchers also reviewed data from 557,720 further patients included in studies across Europe, the United States and Asia, and found similar results.

The research was funded by the British Heart Foundation (BHF).

Prof Gavin Murphy, BHF professor of cardiac surgery at the University of Leicester, said: “Obesity is a reason often given for not offering patients surgery.

“With this study, we show that, for cardiac patients at least, being obese should not be a reason to turn patients away from surgery.

“These results also raise questions as to whether there may be attributes of obesity that directly protect patients.

“Understanding these processes may open the door to new prevention strategies or treatments.”