New research presented at the European Association for the Study of Diabetes (EASD) meeting in Vienna indicates that the relationship between body mass index (BMI) and mortality may be more complex than previously thought. The study, which analyzed health data from 85,761 individuals in Denmark, found that those classified as overweight or even mildly obese (BMI 25 to <30 kg/m²) did not exhibit a higher mortality rate over five years than individuals with a BMI in the normal range (22.5 to <25.0 kg/m²).
In contrast, individuals with a BMI in the lower end of the healthy range (18.5 to <20.0 kg/m²) and those categorized as underweight were found to have significantly increased mortality rates. Specifically, underweight individuals were nearly three times more likely to die than those in the reference population, while those with severe obesity (BMI ≥ 40 kg/m²) had more than double the risk.
The findings suggest that being "fat but fit" may not be as detrimental to health as once thought, although those with higher levels of visceral fat may still face metabolic health risks. Researchers noted that factors such as age, sex, and education were taken into account in their analysis.
Dr. Sigrid Bjerge Gribsholt, who led the study, acknowledged that reverse causation could influence results. For instance, weight loss due to underlying health issues may skew mortality data. The study emphasizes the need for a nuanced approach to obesity treatment, taking into consideration fat distribution and associated health conditions rather than solely relying on BMI as an indicator of health risks.