Your brain uses 20% of your body’s energy—400-500 calories daily—despite being only 2% of body weight. Research by George Cahill established that ketones can supply up to 60-70% of brain energy during fasting. The brain isn’t fragile; it evolved to function through food scarcity, shifting between glucose and ketones seamlessly.
This companion covers the brain’s fuel sources, the blood sugar myth, cognitive performance during fasting, and why constant snacking isn’t necessary for brain function. (3 min read)