The body mass index (BMI), a commonly used tool to evaluate weight in relation to height, has a history that is more complex than its widespread use might suggest. At a roundtable discussion titled Obésité, the disease of the century: anatomy of a silent epidemic, held on October 6, 2026, at the Espace Pavé in Paris, Dr. Karine Clément—an endocrinologist, diabetologist, and nutritionist—spoke about how American insurance companies played an unexpected role in shaping the link between weight and health risk. Dr. Clément asked the audience to consider the origins of the BMI, explaining that it was defined in 1950 by American insurance companies as a way to charge higher premiums for individuals classified as obese. Although the mathematical formula used to calculate BMI—weight divided by height squared—was developed earlier, its use as a health indicator was influenced by economic motives. This approach reflected a practical need for insurance firms to assess risk and set rates. The conventional threshold of 30 for obesity in adults, according to Dr. Clément, was established in this context. This benchmark has since become a standard in public health and medical practice, even though its origins were rooted in financial considerations rather than purely health-related concerns. Dr. Clément’s remarks prompted reflection on how economic interests have shaped medical definitions and public health policies. The discussion highlighted the importance of examining the historical and economic factors that influence health metrics. While the BMI remains a widely used tool, its limitations and origins underscore the need for a more nuanced understanding of health and weight. This conversation is part of a broader effort to address the complexities of obesity as both a medical and societal issue.