Here’s a fourth major guideline to assist you in your fast. Whether or not you are focusing on the spiritual aspect, adding breathing exercises will bring more oxygen to the fire. After all, whether you’re in ketosis or burning sugar, your body makes energy by combining air and food to generate electrons.

The bike experiment is a repeat of several studies conducted 20 years earlier by Dr. John Douillard, a trainer to elite athletes, from tennis star Billie Jean King to triathletes to the New Jersey Nets. In the 1990s, Douillard became convinced that mouthbreathing was hurting his clients. To prove it, he gathered a group of professional cyclists, ri