Stroke risk from obesity is now measurable

Researchers at Brigham and Women’s Hospital (BWH) in Boston have determined that obesity is a measurable risk factor for stroke in men, and have calculated that risk in terms of the popular equation used to measure obesity, known as the Body Mass Index, or BMI.

For 12 years, 21,414 physicians who participated in the long-running Physicians’ Health Study, had their BMI – their weight in kilograms divided by the square of their height in meters – recorded. In all, 747 strokes occurred. Men with a BMI of 30 or higher were found to be twice as likely to have a stroke compared with men who had a BMI of less than 23.

While it has been suspected for some time that being overweight could potentially increase a person’s chances of a stroke, the BWH study, published in the Dec. 9 issue of the Archives of Internal Medicine, offers some of the first concrete evidence that as a man’s weight increases, so do his chances of suffering from a stroke.

Stroke accounts for one in every 14 deaths in the United States, making it the third leading cause of death and disability in the nation.

“Other research has convincingly shown that obesity is linked to coronary heart disease, but the stroke risk associated with weight gain has, until this study, been a debatable issue,” said Tobias Kurth of BWH. “We were able to show that there is a quantifiable increase in your chances of having a stroke when you are overweight or obese.”

The analysis also showed that for each unit increase in BMI, a man’s chances of having a stroke increased by 6 percent. Generally, a unit increase in BMI translates into a weight gain of roughly 7.4 pounds for a 6-foot man and 6.2 pounds for a 5-foot-6-inch man.

At the beginning of the study, participants ranged in age from 40 to 84 years old and had no history or stroke, cancer, or heart attack. The study’s results were basically unchanged when adjustment was made for other risks for stroke, such as hypertension, diabetes, and cholesterol.

A person who has a BMI of 25 or greater is generally considered overweight, whereas a person with a BMI of 30 or greater is categorized as obese. Nearly two-thirds of the adult population of the United States is overweight.

“Our findings underscore the fact that your risk of stroke is modifiable when it comes to how much you weigh,” said Kurth. “The prevention of stroke may be another benefit associated with preventing excess weight and obesity in adults.”