John A. McDougall was an American physician, author, and advocate of low-fat, plant-based nutrition. After surviving a stroke at 18, he pursued medicine, ultimately creating the McDougall Program, a starch-based vegan diet aimed at preventing and reversing chronic disease. His bestseller The McDougall Plan popularized his nutritional philosophy, emphasizing unprocessed starches, vegetables, and fruit while eliminating all animal products, oils, and processed foods. Over his career, McDougall published multiple books, sold more than 1.5 million copies, and co-founded Dr. McDougall's Right Foods. McDougall ran a 10-day residential health program in California and appeared frequently in media to promote dietary change. He also served on the advisory board of the Physicians Committee for Responsible Medicine and was a plaintiff in a lawsuit challenging federal cholesterol guidelines. In 2018, he received the Lifetime Achievement Award from the American College of Lifestyle Medicine. Though praised by supporters for his unwavering commitment to diet-based healing, McDougall also faced criticism for promoting what some experts labeled as a restrictive “fad diet.” Concerns included potential nutritional deficiencies and the exclusion of entire food groups like nuts and oils. Nonetheless, studies reported health improvements among adherents, and the American Heart Association acknowledged partial alignment with its dietary guidelines. McDougall's work significantly influenced the plant-based movement and helped reshape public understanding of nutrition’s role in health. Despite controversy, his emphasis on whole foods and dietary simplicity made lasting contributions to preventive medicine and lifestyle change.