The article discusses the pathogenesis of obesity, focusing on two prominent models: the Energy Balance Model (EBM) and the Carbohydrate-Insulin Model (CIM). These models attempt to explain the development of obesity within the broader framework of human energy metabolism regulation. The EBM posits that increased obesity prevalence is driven by a positive energy balance, primarily due to increased food intake, while the CIM suggests that altered fuel partitioning, favoring storage over oxidation, is the primary cause. The workshop in Copenhagen aimed to operationalize terms, delineate model structures, discuss causal factors, and brainstorm key scientific questions. The EBM and CIM differ in their mechanisms of action, with the EBM focusing on the brain's disruption of energy sensing and the CIM on peripheral fuel partitioning. Both models acknowledge the role of various biological, behavioral, and environmental factors. The article emphasizes the need for more experimental research to test these models and understand the complex mechanisms of obesity. It also highlights the importance of addressing sociocultural factors and the need for rigorous, controlled studies to advance the field.The article discusses the pathogenesis of obesity, focusing on two prominent models: the Energy Balance Model (EBM) and the Carbohydrate-Insulin Model (CIM). These models attempt to explain the development of obesity within the broader framework of human energy metabolism regulation. The EBM posits that increased obesity prevalence is driven by a positive energy balance, primarily due to increased food intake, while the CIM suggests that altered fuel partitioning, favoring storage over oxidation, is the primary cause. The workshop in Copenhagen aimed to operationalize terms, delineate model structures, discuss causal factors, and brainstorm key scientific questions. The EBM and CIM differ in their mechanisms of action, with the EBM focusing on the brain's disruption of energy sensing and the CIM on peripheral fuel partitioning. Both models acknowledge the role of various biological, behavioral, and environmental factors. The article emphasizes the need for more experimental research to test these models and understand the complex mechanisms of obesity. It also highlights the importance of addressing sociocultural factors and the need for rigorous, controlled studies to advance the field.