Research indicates that stroke survivors who are slightly overweight tend to have a reduced likelihood of experiencing disabilities. The findings from Kobe University contribute to the understanding of the obesity paradox and emphasize the need to consider what is typical for the population when advising best practices.
The obesity paradox refers to the established observation that among individuals who have had a stroke, those with moderate overweight status exhibit lower rates of death, recurrence, and hospital readmission than those deemed to have “normal” weight. Recently, as survival rates have improved, the focus has shifted to the quality of life for these individuals after the stroke. IZAWA Kazuhiro, a health scientist at Kobe University, notes, “In my clinical experience, I have found that patients with a slender build often struggle to regain functionality, while those who are slightly overweight generally recover better. This prompted me to investigate the potential link between body size and functional outcomes following a stroke.”
To explore this, Izawa, along with postdoctoral researcher KANEJIMA Yuji and their team, analyzed data from a national database in Japan that contained anonymized information on diagnosis-procedure combinations for all vascular and cardiac disease cases across hospitals. They assessed various factors affecting the disabilities of over half a million stroke patients at the time of their hospital discharge. The factors included body mass index (BMI), which measures weight relative to height, as well as the patients’ age, gender, and initial disability scores upon admission, among others.
The results were published in the journal Topics in Stroke Rehabilitation. The research revealed that individuals with a BMI between 22.1 and 27.5 kg/m2 had a lower risk of being discharged with poor disability scores, with the lowest risk noted at a BMI of 24.7 kg/m2. Notably, the World Health Organization (WHO) defines Asians with a BMI of 23 to 25 kg/m2 as overweight, with those above being classified as obese. This suggests that a slightly higher than average BMI can be advantageous for recovery from stroke with minimal disability. Kanejima provides insight, stating, “The average age of participants was 77, and older adults tend to lose weight more easily. Those with certain reserves may better handle the nutritional challenges posed by a stroke and subsequent hospitalization, providing protection to their nervous systems.”
A similar investigation carried out in the United States a few years ago found a comparable trend, indicating an optimal BMI of 30.0 kg/m2 for that demographic. “Asians generally have a slimmer build than Americans, which is reflected in the lower optimal BMI observed for reduced disability risk,” explains Kanejima. This points to the necessity for careful application of BMI-based guidelines across different global populations.
The findings from this study offer valuable guidance for health care practices. Izawa remarks, “For the general public, this serves as a reminder that weight loss in older age can be detrimental. For health care professionals, this study highlights the importance of monitoring weight loss during hospitalization to avoid functional decline.” To further understand the mechanisms involved, the researchers at Kobe University plan to investigate how changes in body weight during hospitalization relate to functional disabilities.
This research received funding from the Japanese Circulation Society and the Japan Society for the Promotion of Science (grants JP22K11392 and JP22K19708) and was conducted in partnership with experts from the National Cerebral and Cardiovascular Center.
