Fast this way

A burned-out Silicon Valley entrepreneur sits cross-legged in a red-rock cave near Sedona, water bottle at his side, watching a bald eagle feather drift across the floor. He weighs three hundred pounds at his worst. He has Hashimoto's thyroiditis from mold exposure, brain fog he can taste, and a Wharton MBA he earned while running on four hours of sleep a night. The shaman who drove him here in a beat-up pickup told him only two things: do not talk to the other seeker camping a mile away, and keep your phone off except for one minute each morning. He has no food for four days. And for the first time in his adult life, he is about to stop confusing hunger with craving.

This is the opening Dave Asprey returns to throughout Fast This Way, and it is the right starting point, because the book is not really about food. It is about the gap between a biological signal and the story you tell yourself about that signal. Asprey wants you to learn that gap. Everything else — the butter coffee, the supplement stack, the protocols for women in perimenopause — flows from that single insight. Hunger is information. Craving is a hostage situation. Fasting is how you find out which one you are dealing with.

Chapter 1: Fasting Lives in Your Head

Asprey defines fasting as "going without," and immediately pushes the definition past food. Sobriety is going without substances. Meditation is going without thinking. The Sabbath is going without work. Hypoxic training is going without oxygen, the way endurance athletes prepare in Albuquerque and Chamonix. Cameron Sepah, a psychologist at UCSF, coined the dopamine fast, which means going without instant gratification — shopping, gaming, alcohol, the bottomless scroll. Asprey himself gave up television during his MBA and never bought one back. By his rough count, that has saved him a few thousand dollars and many thousands of hours.