Fasting. You can train yourself to go from 8 hours (sleep) to 16 hours pretty easily. Once you get to a point where you can one-meal-a-day comfortably, then e

Fasting. You can train yourself to go from 8 hours (sleep) to 16 hours pretty easily. Once you get to a point where you can one-meal-a-day comfortably, then extending this to a 48hr fast once a week becomes relatively easy too.