While obesity has known to be a key risk factor in many diseases, a new study suggests having some extra body fat may be linked to an increased chance of surviving a stroke.

"It was noticed that carrying extra weight may play a role in survival for people who had suffered from kidney and heart disease, We felt the need to investigate whether it also was tied to improved stroke survival," said Zuolu Liu, researcher at the University of California-Los Angeles.

The study, presented at the American Academy of Neurology's 71st annual meeting in the US, found that severely obese people were 62 per cent less likely to die than people of normal weight. Obese people were 46 per cent less likely to die after a stroke and those who were overweight had 15 per cent more chances of survival.

Conversely, underweight people were 67 per cent more likely to die after a stroke than people of normal weight. The condition called the obesity paradox suggests being overweight may be protective for some, such as old people or those with certain chronic diseases.

"One possible explanation is people who are overweight or obese may have a nutritional reserve that may help them survive during prolonged illness. More research is needed to investigate the relationship between body mass index and stroke," Liu stated. For the study, the team looked at 1,033 stroke-affected people with an average age of 71 and an average body mass index (BMI) of 27.5.