A large, long-term study has shown that waist circumference (WC), when used alongside body mass index (BMI), offers better insight into mortality risk among postmenopausal women—especially those with a normal or overweight BMI.
The study analysed data from over 139,000 postmenopausal women in the United States over a median follow-up of 24 years. It found that having a larger waist—even at a “healthy” BMI—was associated with a significantly higher risk of death, similar to that seen in women with obesity.
Led by Aaron K. Aragaki, MS, and colleagues, the study evaluated whether stratifying BMI categories by WC thresholds specific to BMI levels could improve long-term mortality prediction.
For example, women with normal BMI but high WC had a 17% higher risk of mortality compared to those with both normal BMI and WC. Among women with overweight BMI and large WC, mortality risk increased by 19%, reaching levels equivalent to those with class 1 obesity (BMI 30–34.9) but normal WC.
The study used data from the Women’s Health Initiative, with participants aged 50–79 years at baseline. Researchers applied BMI-specific WC cut-offs (≥80 cm for normal BMI, ≥90 cm for overweight, and higher for obesity categories) and tested their value in predicting mortality at 10 and 20 years.
The models combining BMI and WC modestly improved mortality risk stratification in a cohort with high rates of overweight and obesity, improving both discrimination and reclassification metrics. In a more geographically diverse cohort, the improvement in discrimination was less consistent, though stratification still improved.
Importantly, the study found that WC offered additional insight across all BMI levels, reinforcing the importance of assessing central fat distribution—not just total body mass—when evaluating long-term health risks.
While these findings may not extend to men or younger women, they underscore a simple clinical message: waist circumference matters, even when BMI appears “normal.”
Reference
Aragaki AK et al. Development and Validation of Body Mass Index–Specific Waist Circumference Thresholds in Postmenopausal Women: A Prospective Cohort Study. Ann Intern Med. 2025;DOI: 10.7326/ANNALS-24-00713.
