Impact of Body Weight on Stroke Outcomes

Body weight, most commonly assessed by body mass index (BMI), exerts a complex influence on both the risk of stroke and its subsequent outcomes. Excess adiposity promotes hypertension, dyslipidaemia and insulin resistance, heightening the incidence of ischaemic stroke, while leanness can predispose to haemorrhagic events. Paradoxically, numerous observational studies report improved survival and functional recovery among overweight or mildly obese stroke survivors compared with those of normal weight, a phenomenon termed the “obesity paradox”. This non-linear relation between BMI and outcome appears to vary with age, stroke severity and comorbidities. Underweight patients often fare worse, with higher mortality and greater disability, whereas those in the overweight category may demonstrate enhanced resilience during acute care and rehabilitation. Mechanistic explanations invoke differential inflammatory responses, neuroprotective adipokines and energy reserves that may support recovery. Understanding these weight-related effects has global significance for tailoring prevention strategies, optimising acute management and guiding poststroke rehabilitation programmes.

Research from Nature Portfolio

Recent investigations have clarified the non-linear association between BMI and poststroke functional status. In a large observational cohort, patients classified as overweight exhibited lower odds of poor functional outcome at three months compared with those of normal weight, while underweight individuals faced increased risk. Advanced modelling including restricted cubic splines and machine-learning explainability techniques confirmed a U-shaped relationship, with optimal prognosis in the overweight range and diminished benefit in the obese category. Crucially, these associations persisted after excluding fatal cases and adjusting for demographic and clinical covariates, and were most pronounced among older adults and those with milder initial deficits. Earlier foundational work in a national, multicentre register indicated that underweight status independently predicted higher mortality and dependency at both three and twelve months post-ischaemic stroke, whereas overweight and obesity were not associated with significant survival advantage once baseline health and treatment factors were accounted for.

Impact of Body Weight on Stroke Outcomes publication trend

The graph below shows the total number of articles in impact of body weight on stroke outcomes across all publications each year (not limited to Nature Index journals).

Technical terms

Body Mass Index (BMI): A person’s weight in kilograms divided by the square of height in metres, used to categorise underweight, normal weight, overweight and obesity.

Obesity paradox: The observation that overweight or mildly obese patients may exhibit better survival and functional outcomes after stroke compared with normal-weight individuals.

Modified Rankin Scale (mRS): A standardised scale (0–6) that measures the degree of disability or dependence in daily activities following stroke.

Triglyceride-Glucose Index (TyG): A calculated marker combining fasting triglyceride and glucose levels, serving as a surrogate measure of insulin resistance.

Homeostasis Model Assessment of Insulin Resistance (HOMA-IR): A mathematical method using fasting insulin and glucose concentrations to estimate insulin resistance.

References

1. A Nonlinear Relation between Body Mass Index and Long-Term Poststroke Functional Outcome—The Importance of Insulin Resistance, Inflammation, and Insulin-like Growth Factor-Binding Protein-1. International Journal of Molecular Sciences (2024).
2. Correlation of TyG-BMI and TyG-WC with severity and short-term outcome in new-onset acute ischemic stroke. Frontiers in Endocrinology (2024).
3. Non-linear association between body weight and functional outcome after acute ischemic stroke. Scientific Reports (2023).
4. Association of body mass index with mortality and functional outcome after acute ischemic stroke. Scientific Reports (2017).