Stroke is a common cause of disability and is a prevalent worldwide health concern. It is reported in the literature as the fourth leading cause of death within the United States and for those who survive and work through the rehabilitative process, the impact of stroke can be devastating on a person’s health and overall function. Given the frequency and severity of the impact of this health condition, lowering stroke risk is an important health priority.
Stroke is broadly classified into two types: hemorrhagic or nonhemorrhagic. Hemorrhagic stroke results from the rupture of cerebral blood vessels, whereas ischemic stroke occurs as a result of thrombi or emboli creating blockages in cerebral vessels, occluding blood supply. The prognosis for these two types of strokes is variable according to the literature, with some studies reporting a similar outcome for both types of stroke and others describing a potentially less devastating outcome for those with ischemic stroke.
There are a variety of known risk factors for stroke, both modifiable and nonmodifiable. In this article, we will explore the connection between the modifiable risk factor, obesity; and stroke risk. We will further explore the role that body composition factors can play in stroke prevention.
Known Risk Factors for Stroke
Stroke risk factors can be categorized into those that cannot be altered, known as nonmodifiable risk factors. Nonmodifiable risk factors include things such as your age, sex, race, and ethnicity, which should be taken into account when considering stroke risk; however, that will not be the focus of this particular conversation.
Instead, we will focus on modifiable risk factors, which relate to lifestyle habits and other controllable health conditions. These modifiable risk factors can typically be influenced by the introduction of certain healthy habits and positive behavior changes, potentially lowering a person’s blood pressure and risk of disease, heart attacks, and stroke.
Known modifiable risk factors for stroke risk, include sedentary behavior, poor diet, obesity, and metabolic syndrome. It is debated in the literature just how obesity may play a role in stroke risk, however, obesity has been shown to be linked to other known stroke risk factors, including hypertension (high blood pressure), diabetes and high cholesterol.
Further described in the literature is a connection between “increased abdominal adiposity, as measured by the waist-to-hip ratio” as an increasingly recognized stroke risk. But more on that later.
Obesity and the Stroke Risk Connection
Obesity is a common health concern in the general public and plays a role in many chronic conditions. It has not been well documented, however, estimates indicate that the prevalence of obesity may be somewhere between 18 to 44% among stroke patients.
The literature describes that obesity plays a role in several mechanisms that may contribute to progressing atherosclerosis and/or the development of thromboembolism, which may result in blockage or breakage of the artery. Essentially, obesity-related risk factors have been shown to promote the pathogenesis of stroke.
The mechanism of atherosclerosis, or the build-up of fat and other substances within the arteries, is complex, with many influencing factors. Adipose tissue itself as a factor has been shown to be both endocrinologically and immunologically active. Meaning, that adipose tissue is more than just a passive insulator for our body. Under circumstances of excess adiposity (or excess body fat), increased inflammation and remodeling of tissue can occur, which has been shown to promote the atherosclerotic process, increasing stroke risk.
Obese stroke survivors have also been shown as more likely to have certain cardiovascular risk factors that may increase for having a second stroke or lead to worsened recovery outcomes.
Keep in mind that excess adiposity (or excess body fat) promotes the atherosclerotic process, potentially resulting in a disastrous consequence such as stroke.
The Obesity-Stroke Paradox
While obesity has been established in the literature as a clear risk factor for stroke, prognosis in stroke survival in those who are overweight or obese is controversial. In fact, there are a number of studies that suggest that those with excess weight may even fair better after a stroke; hence the existence of the obesity-stroke paradox.
A systematic literature review set to explore this relationship. A total of 25 studies were identified exploring the complicated relationship between stroke risk and excess body weight. Indeed, a favorable outcome describing excess body weight and stroke prognosis were found in many cases.
Caution is suggested in interpreting these results however, as this study further suggested that “the fatter the better” is an inappropriate interpretation. Mortality (or death rate) was indeed found to be lowest in those individuals who were overweight, but mortality was found to be significantly higher in exceptionally obese and underweight individuals in many studies.
Keeping in mind the value of body composition, those individuals who were found to be obese or underweight, fared worse after stroke.
Investigators from this study continued to support weight reduction in overweight or obese patients for primary stroke prevention, with further study needed in this area. As no randomized controlled trials were identified in the literature, a casual relationship needs further study and investigation to interpret these results.
Further research in the area of body composition and exploring the relationship of Body Mass Index and body fat distribution, would be of definite value in this area.
Abdominal Obesity Specifically
Although obesity has been cited as a risk factor for stroke, few studies have examined the relationship between body composition and stroke risk, specifically. Looking at the relationship between abdominal obesity and stroke risk, a particular study of 576 cases of ischemic stroke was undertaken in New York City. Results showed that increased waist to hip ratio was associated with a greater risk of stroke in both men and women and in all race-ethnic groups.
This study went on further to describe that:
- Abdominal obesity is an independent risk factor for ischemic stroke across all ethnicities.
- Abdominal obesity is considered a more robust risk factor than Body Mass Index (BMI).
- Abdominal obesity has a greater negative effect on younger people.
The effects of body composition and abdominal obesity specifically require consideration as described in the literature. Available data support that when considering body composition and specifically waist to hip ratio, there is a “significant and independent association between ischemic stroke and abdominal obesity”.
Consideration should be given to the role of body composition, body fat distribution (notably, lowering abdominal obesity) and their effects on positively influencing stroke risk.
Influencing Modifiable Risk Factors
As we have already discussed, there are a number of associated comorbid conditions associated with stroke, including diabetes, hypertension, and hyperlipidemia (or high cholesterol). These complications can increase your risk of stroke.
These modifiable risk factors have also been found to be associated with obesity in general. More specifically, factors associated with your body composition have been shown to play a role in your risk level in developing these comorbid conditions, associated with stroke.
According to the research:
- The risk of developing type 2 diabetes is increased in those with increased Body Mass Index and is associated with obesity in all ethnic groups.
- Up to ¼ of cases of hypertension have been cited to be associated with excess body weight.
- In obese individuals, and specifically, those with “central fat distribution” have been shown to be at increased risk for hyperlipidemia.
These complications are the same comorbidities as those associated with stroke. Essentially then, reducing risk factors associated with obesity can also reduce your stroke risk.
It has been estimated that as many as 50% of strokes could be prevented by modifying risk factors and making lifestyle changes. Research supports the connection between reducing the incidence of hypertension, diabetes mellitus and improving HDL “or the good cholesterol” levels, to offer a substantial reduction in stroke risk.
By giving due consideration to our body composition, it is possible to ultimately affect your risk of developing conditions such as hypertension, diabetes, and obesity; which ultimately positively influences your stroke risk.
Paying proper attention to lifestyle factors is key to stroke prevention. Prevention strategies including an increase of physical activity such as aerobic exercise, weight loss in obesity, glucose control in diabetes, smoking cessation, and diet can offer considerable benefit in reducing stroke risk.
Stroke is a devastating health condition, however, your risk can be lowered by taking into consideration certain modifiable risk factors. Implementing lifestyles changes in sedentary behavior, poor diet, and obesity scores, can offer a host of benefits and decrease your risk of health diseases.
Obesity has been identified as a significant modifiable risk factor in stroke and is related to a number of health conditions that can also raise this risk, including hypertension, diabetes, and poor cholesterol scores.
Excess adipose tissue itself has been identified as active metabolic tissue that been linked to the atherosclerotic process and promoting the process of stroke. Awareness of body composition factors, such as waist to hip ratio, BMI and your body fat percentage; offer insight into possibly measurable stroke risk levels. Further research in this area would offer great benefit.
Obesity, and more specifically, abdominal obesity has been identified as an important and potent risk factor in stroke prevention. Research supports that positively influencing waist to hip ratio and lowering abdominal obesity is of significant clinical value in prevention.
Considering body composition, the same comorbid conditions associated with stroke risk, are also associated with obesity. Positively influencing your body composition, including focusing on targeting a healthy body fat percentage and a reduction in abdominal obesity through an increase in physical activity may offer positive benefits in regard to lowering your stroke risk.
Dr. Jennifer Malowney is a practicing chiropractor, with an interest in preventative health. Her knowledge and clinical experience in the areas of health, fitness, and nutrition offer readers an informed and well-researched perspective.