FASTING: A 3 Organ Concert

Maintenance of energy sources during fasting in the bloodstream depends on three organs acting in concert: 1. The liver which provides the bloodstream with glucose and ketone bodies; 2. Adipose tissue which provides the bloodstream with fatty acids; and 3. The muscle which provides lactate, alanine, and other amino acids as gluconeogenic precursors for glucose de novo synthesis in the liver. These actions are mostly controlled by a rise in both epinephrine and glucagon during fasting.