Women who carry excess weight as teens or young adults have a higher risk of stroke by middle age, a new study suggests.

For the study, researchers followed more than 10,000 people over four decades, assessing their body mass index (BMI), a ratio of weight to height, at ages 14 and 31 to see if being overweight at those points in life influenced the risk of stroke before age 55.

During the study, 452 people had a stroke. Most cases were ischemic strokes, when clots block blood flow to the brain, or transient ischemic attacks, or “ministrokes,” which happen when clots stop blood flow for only a few minutes before they dissolve or get dislodged.

“Women who are overweight as teens or young adults have an increased risk of stroke in middle age because excess weight can lead to health problems that damage blood vessels over time,” says the lead study author, Ursula Mikkola, a population health researcher at the University of Oulu in Finland.

Why Being Overweight Raises the Risk of Stroke

Carrying extra weight causes chronic inflammation in the body, which can damage blood vessels, Mikkola says. Individuals who are overweight or have obesity are also more prone to stroke risk factors like high blood pressure, elevated blood sugar, and high cholesterol — and the risk of stroke is higher if these conditions persist for many years.

“These conditions can cause damage to blood vessels that can lead to stroke,” says Carolyn Cronin, MD, PhD, an associate professor of neurology at the University of Maryland School of Medicine and the medical director of the Maryland Young Stroke Center in Baltimore.

“The damage typically accumulates slowly over time, leading to problems later in life,” says Dr. Cronin, who wasn’t involved in the new study.

While the study wasn’t designed to prove whether or how excess weight might directly cause strokes — or why the risk might differ between the sexes — it’s possible that hormonal differences that women experience during puberty, pregnancy, and menopause might play a role, Mikkola says.

Treating Stroke Risk Factors to Encourage Prevention

The study results underscore the importance of maintaining a healthy weight, and considering options like weight loss medications or surgical weight loss if you carry excess pounds and have other risk factors for stroke, says Nishant Shah, MD, an assistant professor of cardiology at the Duke University School of Medicine in Durham, North Carolina, who wasn’t involved in the new study.

“It is important to live the best heart-healthy lifestyle you can,” Dr. Shah advises. That’s because protecting your cardiovascular system is key to avoiding blood vessel damage that can lead to strokes.

Steps to prevent heart attacks that also reduce stroke risk can include screening for and treating high blood pressure, elevated cholesterol, and high blood sugar, says Larry Goldstein, MD, a professor and the chair of neurology at the University of Kentucky in Lexington, who wasn’t involved in the new study.

“Stroke risk can be reduced by identifying risk factors and following a healthy lifestyle, such as getting regular exercise, following a healthy diet such as a Mediterranean type diet, not smoking and avoiding environmental tobacco smoke, not consuming alcohol to excess, and getting adequate sleep,” Dr. Goldstein says.