Obese cardiac patients are more likely to survive than their normal weight peers, scientists claim.
The University College London researchers studied more than 4,400 patients and found that despite obese heart patients reporting worse health and being less likely to follow lifestyle advice, they are less likely to die than their normal weight peers.
It is not the first time researchers have pointed out this paradox, that being overweight or obese - a risk factor for heart disease in itself - can actually lead to a better prognosis, BBC News reported.
One theory has been that maybe such patients were fitter, despite their size - taking more exercise for example.
To see if this was the case, researchers looked at data from patients who took part in the Health Survey for England or Scottish Health Survey.
They found that, as with other studies, patients with cardiovascular disease who were obese or overweight were less likely to die over the next seven years than people of a normal weight who had the condition.
In all 31 per cent of patients were obese - that is with a body mass index of 30 or more.
Those patients tended to be younger but reported worse health and had more heart risk factors such as raised cholesterol and blood pressure, but were less likely to smoke.
The researchers reported in journal Preventive Medicine that those who took part in physical activity at least once a week and did not smoke had a lower risk of death whatever their weight.
But obese patients who did not stick to these healthy lifestyle recommendations still had a lower risk of death than normal weight patients who smoked or were inactive.
Study leader Dr Mark Hamer said they were trying to explain why obese heart patients seemed to do better by looking at lifestyle factors, but they found that it was not the case that obese patients were healthier.
"We don't yet understand this paradox and we would clearly not advise patients to put on weight," Hamer said.
"One of the more sensible explanations may be that when obese patients present to their doctor, they are given more aggressive treatment because they are seen as very high risk," he said.
"We do know, for example with cardiac rehabilitation, that the thing that absolutely works is exercise - that dramatically reduces risk even though you don't necessarily lose weight," he said.
