Our guest today is Dr. Mark Mattson, who is affectionally known as the godfather of intermittent fasting. The National Institute of Health describes Mark as “one of the world’s top experts on the potential cognitive and physical health benefits of intermittent fasting.”  He is considered a leader in the area of cellular and molecular mechanisms underlying neuronal plasticity and neurodegenerative disorders and has made major contributions to understanding the pathogenesis of Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis and stroke, and to their prevention and treatment. After spending nearly 30 years researching calorie restriction and intermittent fasting, Mark has written a book on the topic, “The Intermittent Fasting Revolution: The Science of Optimizing Health and Enhancing Performance.” Our interview with Mark came the day after MIT Press released his book. This is the second time Mark has appeared on STEM-Talk. When we interviewed him back in 2016, intermittent fasting didn’t register on Google’s list of top-10 searches related to diet and eating plans. By 2019, however, intermittent fasting was more widely searched on Google than any other diet. Today, intermittent fasting and the ketogenic diet jockey for Google’s top spot for diet searches. We talk to Mark in this interview about how, as the title of his book suggests, we are indeed in the midst of an intermittent fasting revolution. In today’s episode, Mark walks us through our evolutionary history and how it has sculpted our brains and bodies to function optimally in a fasted state. We talk about ways our overindulgent sedentary lifestyles have negatively impacted not only our waistlines, but also the size of our brains. After describing the various ways to go about intermittent fasting, Mark dives into the science behind fasting. This leads to a fascinating discussion about the metabolic switch that transitions a person from the utilization of glucose to the utilization of fat-derived ketones and how research is showing that this switch becomes an important factor in the treatment of not only cognitive disorders like Alzheimer’s, but also a range of other diseases and disorders like cancer, diabetes, inflammation, kidney, and heart disease. Mark is on the neuroscience faculty at Johns Hopkins University School of Medicine. He recently retired from the National Institute of Aging where he led its neuroscience laboratory for the past 20 years. Show notes: [00:04:16] Dawn opens the interview congratulating Mark on his new book and asks how long it took him to write it. [00:05:09] Dawn mentions that when Mark was last on STEM-Tall in 2016, intermittent fasting was just beginning to come to the public’s attention, and that today it is almost impossible to pass a grocery store checkout counter without seeing a rack of magazine covers touting intermittent fasting. Dawn asks Mark for his thoughts about what happened in the past decade to suddenly spark so much public interest in fasting. [00:08:20] Ken mentions the title of Mark’s new book, “The Intermittent Fasting Revolution: The Science of Optimizing Health and Enhancing Performance.” Ken asks Mark to expound on the idea that we are witnessing a revolution of interest in intermittent fasting. [00:10:39] Dawn explains that the first chapter of Mark’s book begins with an overview of how evolution sculpted humans and animals to function best in a fasted state. Mark, in this section of his book, makes the point that fasting is not a diet, but an eating pattern that puts a person into a fat-burning state. Dawn asks Mark to briefly walk through this evolutionary history. [00:13:06] Ken mentions that Yuval Noah Harari, author of,