Lifestyle Medicine (LM) is a rapidly growing medical specialty that focuses on the role of lifestyle factors in preventing, managing, and reversing chronic diseases. The 6 pillars of LM—whole-food, plant-predominant diet, physical activity, restorative sleep, stress management, avoidance of risky substances, and positive social connections—are central to its approach. LM began as a medical specialty in 2004 and has since grown significantly, with over 9000 active members in 2022. The American College of Lifestyle Medicine (ACLM) has played a pivotal role in establishing LM, providing education, certification, and a governing body. LM is distinct from conventional medicine and other medical fields like integrative and functional medicine, emphasizing the importance of lifestyle changes for health. Key studies, such as the Diabetes Prevention Program and the Lifestyle Heart Trial, have demonstrated the effectiveness of LM interventions in preventing and reversing chronic diseases. LM also addresses social determinants of health and aims to improve health equity. Despite challenges such as limited awareness, institutional resistance, and resource constraints, LM shows promise in transforming healthcare by promoting holistic health and improving population outcomes.Lifestyle Medicine (LM) is a rapidly growing medical specialty that focuses on the role of lifestyle factors in preventing, managing, and reversing chronic diseases. The 6 pillars of LM—whole-food, plant-predominant diet, physical activity, restorative sleep, stress management, avoidance of risky substances, and positive social connections—are central to its approach. LM began as a medical specialty in 2004 and has since grown significantly, with over 9000 active members in 2022. The American College of Lifestyle Medicine (ACLM) has played a pivotal role in establishing LM, providing education, certification, and a governing body. LM is distinct from conventional medicine and other medical fields like integrative and functional medicine, emphasizing the importance of lifestyle changes for health. Key studies, such as the Diabetes Prevention Program and the Lifestyle Heart Trial, have demonstrated the effectiveness of LM interventions in preventing and reversing chronic diseases. LM also addresses social determinants of health and aims to improve health equity. Despite challenges such as limited awareness, institutional resistance, and resource constraints, LM shows promise in transforming healthcare by promoting holistic health and improving population outcomes.