Moving away from BMI: a new era of diagnostic criteria in obesity

Obesity is a chronic, progressive, and heterogeneous disease defined by excess adiposity that impairs health. While Body Mass Index (BMI) remains the most used diagnostic tool, it is increasingly regarded as an inadequate measure of obesity. BMI does not account for inter-individual, including inter-ethnic variation in fat distribution, body composition and metabolic health. These limitations highlight the need for a more nuanced and clinically robust diagnostic framework in obesity. This article examines the shortcomings of BMI as a diagnostic tool and explores a range of alternative metrics, including anthropometric indices, clinical staging systems and direct assessments of adiposity and metabolic dysfunction, drawing on a narrative review of literature from 1950 to 2025 using PubMed. We also review recent international expert consensus statements and updated clinical guidelines from leading health organizations. Research progress in obesity diagnostics is expected to drive a shift away from BMI toward more clinically useful approaches. Future clinical practice could adopt more personalized management strategies, to guide prevention, diagnosis, and intervention in obesity care.