'Obesity paradox': Study finds common health metric could be misleading for older people

A recent study has challenged conventional wisdom surrounding body mass index (BMI) as a health indicator for older adults, revealing that a "normal" BMI might not always reflect a lower risk of mortality. Researchers found that factors such as waist circumference, muscle mass, and overall health should be taken into account alongside BMI to better assess health risks in individuals aged 65 and over. This finding suggests that the traditional reliance on BMI alone could be misleading, especially when evaluating the health status of elderly populations. The study analyzed data from 6,905 U.S. adults aged 65 and older, collected over a 14-year period from 2011 to 2024 through the National Health and Aging Trends Study. The researchers examined how different BMI categories correlated with mortality rates. They discovered that being overweight was linked to a significantly lower mortality risk compared to those with a normal BMI, particularly among men. For instance, men who were classified as overweight had a 46 percent lower mortality hazard than those with a normal BMI. Similarly, men with Class I or II obesity experienced a 51 percent reduction in mortality risk compared to their counterparts with a normal BMI. In contrast, the findings for women were less pronounced. Women who were overweight had a 27 percent lower mortality hazard than those with a normal BMI, but the reduced risk for women with Class I or II obesity was not statistically significant. This discrepancy highlights potential gender differences in how BMI relates to mortality outcomes. However, waist circumference emerged as a more consistent predictor of mortality risk across both genders. Individuals with a waist measurement exceeding 40 inches (102 cm) for men or 35 inches (89 cm) for women faced a 24 percent higher mortality hazard, regardless of their BMI classification. The researchers emphasized that these results do not imply that obesity is beneficial or protective. Rather, they underscore the limitations of using BMI as the sole determinant of health status. BMI calculations rely solely on height and weight, failing to differentiate between muscle and fat mass. Consequently, individuals with a normal BMI but increased abdominal fat, often associated with metabolic syndrome, may still face elevated health risks. Dr. Bryan Blissmer, one of the study’s co-authors from the University of Rhode Island, noted that combining BMI with other metrics such as waist circumference provides a more comprehensive view of health risks in older adults. He suggested that this integrated approach could enhance mortality risk assessments and guide more effective clinical decisions. According to the study, individuals with a normal BMI but large waist measurements exhibited higher mortality hazards, men by 33 percent and women by 23 percent, indicating that BMI alone might obscure underlying health concerns. Additionally, the study revealed that being underweight posed nearly double the mortality risk compared to those within the normal BMI range, reinforcing the importance of maintaining a healthy weight. These findings call into question the universal applicability of BMI as a health metric, particularly for aging populations whose body compositions differ significantly from younger individuals. As healthcare professionals and policymakers reassess guidelines, the integration of additional physiological indicators may become essential in accurately assessing and managing health risks in older adults.