Quantity
If you’re interested in trying the five-day, fasting-mimicking diet from Prolon or just want to read up a bit on the theory behind the practice, this book by Valter Longo, PhD, the scientist behind the protocol, is the best resource for deeper learning. It describes the research behind everyday pescatarianism and once-in-a-while calorie restriction for longevity and overall well-being—and demonstrates how achievable a long and healthy life could be.