Illustration symbolizing the connection between body weight and brain health.

Decoding Your BMI: How It Impacts Your Stroke Risk

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Jordan Keane in Health & Wellness October 2026 • 4 min read.

"New research sheds light on the surprising link between body mass index and different types of strokes, helping you understand your risk and take proactive steps."


Stroke is a leading cause of long-term disability and mortality globally. While the connection between overall weight and stroke risk is well-established, recent research delves deeper into how body mass index (BMI) relates to specific types of ischemic strokes, such as lacunar, large-artery occlusive, and cardioembolic strokes.

A groundbreaking study, the Japan Public Health Center-based Prospective (JPHC) Study, followed over 88,000 men and women for two decades, revealing intriguing patterns between BMI and the risk of these stroke subtypes. This article translates the study's findings into practical knowledge, empowering you to understand your individual risk and make informed decisions about your health.

We'll explore how cumulative average BMI—calculated using long-term weight and height measurements—shows a distinct correlation with different stroke types. Understanding these nuances can help you and your healthcare provider develop a more targeted approach to stroke prevention.

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BMI Evidence and Its Limits

BMI is commonly examined as a measure of adiposity when researchers assess stroke risk. However, findings have varied, prompting meta-analyses such as the 2022 study published in the Journal of Neurology and the 2018 systematic review of prospective studies on the shape of the BMI–stroke relationship. Research has also examined BMI in relation to stroke recurrence, including a 2025 dose–response meta-analysis. These differing results show that BMI-based associations with stroke risk are not fully consistent across studies.

BMI and Stroke: Unpacking the Connection

Illustration symbolizing the connection between body weight and brain health.

The JPHC study meticulously tracked participants aged 40-69, collecting data on their weight, height, lifestyle, and medical history. By calculating cumulative average BMI, researchers were able to assess the long-term impact of body weight on stroke risk. The study identified three main subtypes of ischemic stroke:

The study revealed that cumulative average BMI was positively associated with lacunar, large-artery occlusive, and cardioembolic strokes in men, and with lacunar and large-artery occlusive strokes in women. Specifically, the results indicated:

  • Lacunar Strokes: These small vessel strokes showed a consistent positive association with BMI in both men and women.
  • Large-Artery Occlusive Strokes: Similar to lacunar strokes, higher BMI was linked to an increased risk in both sexes.
  • Cardioembolic Strokes: Men with a BMI of 30 kg/m² or higher had approximately twice the risk of cardioembolic stroke compared to those with a BMI between 23 and 25 kg/m². However, this association was not significant in women.
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What Recent Reviews Show

A targeted literature review reports that Japanese adults with obesity, defined in that review as a BMI of at least 25 kg/m2, have increased risks of complications compared with normal-weight adults. A 2022 systematic review and meta-analysis likewise emphasizes the importance of weight control in preventing ischemic strokes. Evidence for hemorrhagic stroke is less consistent: reports have described linear, J-shaped, U-shaped, absent, and inverse relationships with BMI. An updated 2025 systematic review and meta-analysis is re-evaluating BMI and recurrent stroke risk among stroke survivors.

When the Association Changes

The Japan Public Health Center-Based Prospective Study found that the positive association between BMI and large-artery occlusive stroke was not observed in men with hypertension. The same association was also not observed in women without hypertension. The study reported statistically different interaction results for men and women, with P values of 0.01 and 0.08, respectively. This suggests that hypertension status and sex can alter how BMI relates to a specific ischemic stroke subtype.

Different Risk Patterns by Group

The JAMA study assessed age-adjusted relative risk for ischemic stroke across BMI categories using self-reported weight in kilograms divided by height in meters squared, while also considering hypertension status. A 2024 analysis reported that ischemic stroke risk was associated with overweight and obesity in younger women but not in men. That analysis also reported increased hemorrhagic stroke risk with obesity at age 31 in both men and women. These findings indicate that BMI-related stroke patterns can differ by stroke type, age, sex, and hypertension status.

These findings highlight the importance of maintaining a healthy BMI to reduce the risk of various ischemic stroke subtypes. The linear relationship suggests that there may not be a specific cut-off point, reinforcing the need for continuous weight management.

Taking Control of Your Stroke Risk

While the JPHC study provides valuable insights into the relationship between BMI and stroke risk, it's essential to remember that BMI is just one piece of the puzzle. Factors such as blood pressure, cholesterol levels, and lifestyle choices also play significant roles. Talk to your doctor about your individual risk factors and develop a comprehensive plan for stroke prevention. Maintaining a healthy weight through balanced nutrition and regular physical activity is a crucial step in protecting your long-term health. By understanding your risk and taking proactive steps, you can significantly reduce your chances of experiencing a stroke.

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A Global Prevention Challenge

Global research identifies high BMI as an important modifiable factor in the burden of ischemic stroke. The reported pathophysiological mechanisms connecting high BMI with ischemic stroke are multifactorial and well-established. At the same time, effectively treating obesity and ischemic stroke remains a significant clinical challenge. These findings support an urgent need to address ischemic stroke in relation to modifiable risk factors such as BMI.

What a prospective JPHC study can show

Observational study (level 4 of 8)

This observational prospective design can identify associations between long-term BMI and later stroke-subtype incidence, but it cannot establish that BMI caused those outcomes.[1]

What keeps the BMI association from being settled

  • The study did not observe the large-artery occlusive association in men with hypertension or women without hypertension, indicating that subgroup results differed.[2]
  • The apparent absence of an association in women without hypertension may reflect the small number of large-artery occlusive cases.[2]
  • The analysis lacked information on atrial fibrillation and antiplatelet medication, factors relevant to interpreting cardioembolic stroke risk.[2]
  • Because some medical histories were self-reported, unmeasured residual confounding or mediation may remain.[2]
Study at a glance
Study designObservational study[1]
Sample size42,343 men and 46,413 women[1]
SettingJapan Public Health Center-based prospective (JPHC) study[1]
DurationMedian 20.0 years[1]
Main outcomeIncident lacunar, large-artery occlusive, and cardioembolic strokes[1]
Effect sizeBMI ≥30 kg/m2 was associated with approximately two-fold excess risks of cardioembolic stroke in both sexes and lacunar and large-artery occlusive strokes in women[1]
Confidence intervalSHR 2.14; 95% CI, 1.34–3.41[1]
p-valueTrend P < 0.05 for all ischemic stroke subtypes except cardioembolic stroke in women (trend P = 0.14)[1]
FundingNational Cancer Center Research and Development Fund and a Grant-in-Aid for Cancer Research from the Ministry of Health, Labour and Welfare of Japan[1]
Times cited30[1]

Sources

  1. Body Mass Index and Risks of Incident Ischemic Stroke Subtypes: The Japan Public Health Center-Based Prospective (JPHC) Study (Japan Epidemiological Association, 2019)
  2. Body Mass Index and Risks of Incident Ischemic Stroke Subtypes: The Japan Public Health Center-Based Prospective (JPHC) Study (Europe PMC, 2019)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.2188/jea.je20170298, Alternate LINK

Title: Body Mass Index And Risks Of Incident Ischemic Stroke Subtypes: The Japan Public Health Center-Based Prospective (Jphc) Study

Subject: General Medicine

Journal: Journal of Epidemiology

Publisher: Japan Epidemiological Association

Authors: Yuanying Li, Hiroshi Yatsuya, Hiroyasu Iso, Kazumasa Yamagishi, Isao Saito, Yoshihiro Kokubo, Norie Sawada, Shoichiro Tsugane

Published: 2019-09-05

Everything You Need To Know

1

What is BMI, and why should I care about it in relation to stroke?

Body Mass Index, or BMI, is a measure of body fat based on height and weight. It's calculated by dividing a person's weight in kilograms by the square of their height in meters. BMI is significant because it provides a general indicator of whether a person is underweight, normal weight, overweight, or obese, all of which can influence the risk of various health conditions. In the context of stroke risk, BMI helps to assess how a person's weight might be contributing to their likelihood of experiencing different types of ischemic strokes. While BMI is a useful tool, it doesn't account for factors like muscle mass and body composition, so it's important to consider it alongside other health metrics.

2

What is the JPHC study, and what makes it significant?

The Japan Public Health Center-based Prospective (JPHC) Study is a long-term research project that followed over 88,000 men and women for two decades to investigate the relationship between lifestyle factors, including BMI, and the risk of various diseases, including stroke. This study is important because it provides valuable insights into the long-term impact of BMI on different subtypes of ischemic stroke, such as lacunar strokes, large-artery occlusive strokes, and cardioembolic strokes. By tracking participants over an extended period and calculating cumulative average BMI, the JPHC study was able to identify distinct correlations between body weight and specific stroke types, offering a more nuanced understanding of stroke risk.

3

What are the different types of strokes mentioned, and why is it important to know about them?

There are several different kinds of stroke but the study focuses on subtypes of ischemic strokes: lacunar, large-artery occlusive, and cardioembolic. Lacunar strokes are small vessel strokes that occur deep within the brain. Large-artery occlusive strokes involve blockages in the major arteries that supply blood to the brain. Cardioembolic strokes result from blood clots that form in the heart and travel to the brain, blocking blood flow. Understanding these subtypes is important because each has different risk factors and mechanisms. The JPHC study showed different correlations between BMI and these various ischemic stroke subtypes, highlighting the need for targeted prevention strategies.

4

What is cumulative average BMI, and how does it provide a better understanding of risk?

Cumulative average BMI is a calculation that takes into account a person's weight and height measurements over a long period. Instead of relying on a single BMI measurement, cumulative average BMI provides a more comprehensive picture of an individual's weight history. This is important because it reflects the long-term impact of body weight on health outcomes, such as stroke risk. The JPHC study used cumulative average BMI to assess the relationship between body weight and different ischemic stroke subtypes, revealing that long-term weight patterns can have distinct effects on stroke risk.

5

What were the main findings regarding the relationships between BMI and the different types of strokes?

The study indicated that higher BMI was associated with an increased risk of lacunar and large-artery occlusive strokes in both men and women, and with cardioembolic strokes in men. Specifically, men with a BMI of 30 kg/m² or higher had approximately twice the risk of cardioembolic stroke compared to those with a BMI between 23 and 25 kg/m². These findings suggest that maintaining a healthy BMI is crucial for reducing the risk of various ischemic stroke subtypes. The associations identified in the study highlight the importance of continuous weight management and proactive steps to protect long-term health.

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