At 12 hours, you’re transitioning out of the fed state. At 18 hours, fat burning accelerates. At 24 hours, full fasted metabolism with significant ketone production. Research by Anton on flipping the metabolic switch shows each milestone represents deeper shifts into fasted metabolism. At 36 hours, autophagy ramps up aggressively.
This companion covers what happens at each fasting window, individual variation factors, and practical applications for matching fasting durations to your goals. (3 min read)