Being overweight as a teenager increases women's risk of stroke by age 55

According to a study published in the journal Stroke, women who were overweight or obese at age 14 or 31 had an increased risk of ischemic stroke before age 55. Ischemic stroke occurs when a vessel supplying blood to the brain becomes blocked and is the most common type of stroke, accounting for about 87% of all cases.

A study in Finland found that women who were overweight at age 14 had an increased risk of stroke, even if they had lost weight by age 31. Also, women who were overweight at age 31 had an increased risk of stroke, even if they were of normal weight at age 14. Men who were overweight at age 14 or 31 were not found to have an increased risk of ischemic stroke. However, men who were obese at age 31 had an increased risk of hemorrhagic stroke compared to women who were obese at age 31.

"Our findings suggest that being overweight can have long-term health consequences, even if it is temporary," said Ursula Mikkola, lead author of the study and a researcher at the University of Oulu in Finland. "Healthcare professionals should pay attention to overweight and obesity in young people and help them develop healthy eating and physical activity habits. However, conversations with adolescents and young adults about weight should be done without judgment and stigma."

To analyze the relationship between weight at different ages and the risk of stroke up to age 55, the researchers used long-term data from participants in the Northern Finland Birth Cohort 1966. In 1966, more than 12,000 pregnant women from two northern Finnish provinces were included in the study, and more than 10,000 of their offspring, now aged 50, were subsequently followed.

The researchers used body mass index (BMI) to examine whether people who were overweight or obese at age 14 or 31 had different risks of early stroke compared with those who were not overweight or obese at those ages. About 1 in 20 participants experienced an ischemic stroke or transient ischemic attack (TIA, or mini-stroke) over an average follow-up of nearly 39 years after the age 14 assessment and nearly 23 years after the age 31 assessment. The analysis was completed in 2020.

The Impact of Excess Weight on Stroke Risk

• Women who were obese at age 14 were 87% more likely to have an early ischemic stroke or mini-stroke, while women who were obese at age 31 were 167% more likely to have a stroke compared to those who were of normal weight.
• Obese women at age 31 had nearly 3.5 times the risk of hemorrhagic stroke, and obese men at age 31 had more than 5.5 times the risk of hemorrhagic stroke.
• BMI measurements in earlier childhood or later adulthood did not affect the results.

"Living a healthy lifestyle (eating right, not smoking, getting enough sleep, controlling your blood pressure, cholesterol and blood glucose levels, avoiding excess alcohol consumption and being physically active) can reduce your risk of stroke, even if you were overweight when you were younger," Mikkola added.

The study has limitations because it is an analysis of medical data (an observational study) and cannot prove a causal relationship between weight and the risk of early stroke. All participants were born in Finland, so the results may not apply to people in other countries.

"Stroke at a young age is rare, so a difference of just a few cases can make a big difference in risk estimates," Mikkola said. "Also, BMI is based only on a person's height and weight. So a high BMI can be a misleading way to define obesity, especially in muscular people who may have little body fat despite weighing more."

Researchers continue to explore potential reasons for the lack of association between men's increased risk of ischemic stroke and other risk factors in more detail.