Hour 0
The Fast Begins
The moment you stop eating, the clock starts. Your body doesn't know yet that things are different.
What's Happening
Your last meal is digesting. Blood glucose is elevated and insulin is active, signaling cells to store energy. Glycogen synthesis is underway in the liver and muscles.
How You're Feeling
Full, perhaps slightly restless. This is the easiest part — your body has plenty of fuel and nothing has changed yet.