I’m on the fence about this book. There were some things in it that were insightful and that I want to try. I enjoyed hearing about his spiritual fast in a cave, which frames the entire book. Though, it was a little out there for me at times. As a fasting purist, I didn’t like that he repeatedly says that fasting purists are miserable and struggle to make it through each fast. That isn’t the case in my life, and it isn’t the case in many purist IFers’ lives. I think the section where he talks about women and fasting is full of broad generalizations that lack consistent scientific studies to back them. And, while saying he isn’t trying to sell Bulletproof coffee, he does promote it throughout the book. However, I don’t think I am his target audience. This books seems to be more for people who have never tried fasting and know nothing about it. Overall, it is a book that would be a good introduction to fasting for somebody who has never tried it and is curious about fasting.