Dr. Mark Hyman is a physician and best-selling author known for his work in functional medicine. He focuses on treating the root causes of chronic diseases rather than just symptoms. His approach emphasizes the importance of nutrition and lifestyle changes in achieving optimal health. He is the founder and director of the Cleveland Clinic Center for Functional Medicine and has written several books, including Food: What the Heck Should I Eat?. Dr. Hyman is also a prominent speaker and advocate for health policy reform, aiming to improve the healthcare system through a more holistic approach.