The book "Leptin" offers a comprehensive analysis of the discovery and the diverse physiological functions of the hormone leptin, which was discovered in 1994 by Friedman and his colleagues. This discovery marked a significant advancement in the understanding of metabolic processes, energy expenditure, and appetite regulation. While early research focused on the role of leptin in obesity and diabetes, knowledge about its functions has significantly expanded. Today, leptin is recognized as a key player in various physiological areas, including reproductive physiology, cardiovascular health, bone health, immune regulation, as well as cancer research and genetics. The book brings together the latest findings and clinical studies on leptin and provides a valuable overview of its potential therapeutic applications.