Higher BMI Linked to Longer Survival in People Over 90, Major Study Reveals
New research shows that being overweight may actually help nonagenarians and centenarians live longer, challenging conventional BMI wisdom.
Summary
A groundbreaking study of 780 people aged 90 and older found that higher body mass index is associated with longer survival, contradicting standard health advice. Researchers followed participants for six years and discovered that each 5-point BMI increase reduced death risk by 16%. Underweight individuals had the highest mortality rates, while normal and overweight participants lived significantly longer. This suggests that maintaining slightly higher weight in extreme old age may be protective, possibly due to nutritional reserves and age-related metabolic changes that differ from younger adults.
Detailed Summary
This landmark study challenges everything we thought we knew about healthy weight in extreme old age. Researchers tracked 780 French adults aged 90 and older for six years, discovering that higher BMI actually predicts longer survival in this population.
The team analyzed participants from the CEPH Aging Cohort with an average age of 99 years. They used sophisticated statistical models to account for factors like cardiovascular disease, cognitive status, and smoking history while tracking mortality outcomes.
The results were striking: each 5-point BMI increase corresponded to a 16% reduction in death risk. Underweight participants faced the highest mortality rates, while those with normal or overweight BMI lived significantly longer. The protective effect was most pronounced in the oldest participants, suggesting age-related physiological changes alter the BMI-health relationship.
These findings have profound implications for longevity strategies in extreme old age. Unlike younger adults where lower BMI typically correlates with better health, nonagenarians and centenarians may benefit from maintaining higher weight. This could reflect the importance of nutritional reserves, muscle mass preservation, and metabolic adaptations that occur with advanced aging.
However, this research has limitations. The study focused on French participants who already achieved exceptional longevity, potentially limiting generalizability. Additionally, BMI doesn't distinguish between muscle and fat mass, which becomes increasingly important with age. Future research should explore optimal body composition rather than just weight in extreme old age.
Key Findings
- Each 5-point BMI increase reduced mortality risk by 16% in people over 90
- Underweight nonagenarians and centenarians had the highest death rates
- Normal and overweight individuals showed similar survival advantages over underweight peers
- Higher BMI was associated with 23% longer survival time in advanced age
Methodology
Researchers followed 780 French adults aged 90+ (mean age 99.25 years) for six years from the CEPH Aging Cohort. They used Cox proportional hazards models adjusted for age, sex, cardiovascular disease, vulnerability indicators, cognitive status, and smoking history.
Study Limitations
The study was limited to French participants who already achieved exceptional longevity, potentially affecting generalizability. BMI doesn't distinguish between muscle and fat mass, which is crucial in aging populations. The observational design cannot establish causation between higher BMI and improved survival.
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