Since the discovery of leptin, a product of the ob gene, in 1994, there has been a large amount of research identifying the role of this hormone in the maintenance of normal physiology and in disease states. Specifically, the adipokine leptin plays a significant role in the maintenance of homeostasis through modulating cell signalling pathways involved in energy balance and food intake. More recent research has investigated the role of leptin in pathways not linked to satiety, with researchers demonstrating that leptin contributes to other physiological processes including inflammation, respiratory function, bone metabolism, and development. Furthermore, this research has been extended to demonstrate leptin’s mechanistic links to pathologies associated with diseases, particularly those related to obesity.