What Happens to the Body When We Fast: How the Body Changes Its Energy Sources, Hormones, Brain Function, and Internal Processes When Food Is Temporarily Withheld

What really happens inside the human body when we stop eating for several hours or longer? Fasting is much more than an empty stomach. When food is temporarily unavailable, the body begins a remarkable process of adaptation. It changes how it uses energy, adjusts hormone signals, draws on stored resources, and gradually shifts between different fuel sources. In this book, Dr. Marine Zhorzholiani explains these processes in clear, accessible language, taking the reader inside the body to explore what happens during fasting. You will discover: How the body responds during the first hours without food How stored glycogen helps maintain energy availability When and why the body begins using fat as an energy source How ketone bodies are produced and used What happens to the brain during fasting What autophagy is and how it relates to changes in nutrient availability How muscles and proteins participate in energy metabolism How fasting influences hormones, the heart, blood vessels, and digestion Why water and electrolyte balance matters Why short-term food restriction and prolonged fasting are not the same How the body continuously adapts to changing energy availability Rather than presenting fasting as a simple formula, this book explores the physiology behind it — the signals, adaptations, energy pathways, and cellular processes that allow the human body to adjust when food is temporarily unavailable. A fascinating journey into the hidden work your body performs when you are not eating.