Strokes can happen in both men and women, but researchers say one group of women is significantly more at risk than men.

UCLA researchers followed 17,000 people and found women between 45 and 54 years old had double the risk of stroke. But in other age groups, the risk was similar for both men and women.

The difference only pops up in the 45 to 54 year old age bracket, and it's not clear why.

Female hormones and menopause play a role, but experts believe weight and body type are also major factors. Internist Dr. Marie Savard said women should avoid becoming apple shaped.

“As you approach menopause, your body shape changes. Nature is kind of determined to turn all of us into apples,” she said.

With an apple-shaped body, women carry most of their weight around the middle. That can be a problem, because belly fat has been linked to higher cholesterol and blood pressure.

Losing waist size means losing weight, but it's important to concentrate on inches and not just pounds.

“It's not about the scale. It's about the tape measure. What are the inches around your waist?” Savard said.

For the average woman, the waist should be less than 32 inches.

“I think the study is so important for women. The idea that she is twice or more than twice as likely to have a stroke as a man, I think a woman is going to start to pay attention,” Savard said.