Doctors have known for years that carrying too much weight can put you at risk of coronary heart disease and heart attack. Now, new research suggests that losing the battle of the bulge could put you at risk of a stroke.

A study presented Wednesday at the annual meeting of the American Academy of Neurology meeting in Philadelphia suggests that those numbers on your scale could predict your stroke risk.

Dr. Tobias Kurth is a research fellow at the Brigham and Women's Hospital in Boston who studies body mass index, or BMI, the relationship between weight and height. According to World Health Organization guidelines, men with a BMI of 25 to 30 are overweight, while those over 30 are obese.

"High BMI has been identified as an independent risk factor for coronary heart disease and myocardial infarction," Kurth told CBC News Online. "But its role as a risk factor for stroke has been completely controversial over the last decade."

Kurth and his colleagues studied more than 21,000 doctors enrolled in the Physicians Health Study, a massive database of health information about a group of American doctors. The physicians, who were aged 40 to 84, had no history of cancer, heart attack or stroke when they were enrolled in 1982. At that time, their BMI was recorded.

After more than 12 years of follow-up, the doctors had collectively experienced a total of 747 strokes. Those with a BMI higher than 27 had nearly twice the risk for all types of stroke than those with an index of less than 22.

This held true even when Kurth ruled out the secondary effects of increased BMI, like hypertension, which are known risk factors for stroke.

For each one unit increase in a man's BMI, Kurth calculated a six per cent increase of the risk of stroke. Oddly, it appeared that obese people tended to have milder strokes and fewer fatal strokes. "But your risk of getting a hemorrhagic stroke is much increased."

To Kurth, the findings suggest both that increased BMI should be accepted as a risk factor for stroke, and that prevention of weight gain should be used to reduce the risk of stroke – both for men and women.

"Overweight and obesity have been increasing in the last decades ... especially in young people. Stroke remains the third-leading cause of death," Kurth said. "Modifiable risk factors is still a very important issue."

With files from Nicolle Charbonneau in Philadelphia