From Anabolic to Reponic: Reclassifying Insulin’s Primary Metabolic Role

The classification of insulin as primarily an anabolic hormone is inconsistent with its metabolic signature of energy storage. This categorization, shared with anabolic hormones such as testosterone, obscures insulin's role in the pathophysiology of metabolic disease. We propose a more precise classification: reponic, meaning 'to store.' To empirically support this framework, we analyzed data from 2,910 U.S. adults in the National Health and Nutrition Examination Survey 2011-2018. Higher insulin levels were strongly associated with increased central adiposity and dyslipidemia. In contrast, higher testosterone, particularly in males, was associated with a leaner phenotype, reflecting a metabolic profile antagonistic to insulin. These findings reinforce well-established physiology indicating that insulin's primary role is energy storage. Adoption of the reponic classification provides a clearer conceptual framework for understanding hyperinsulinemia and its clinical consequences.