This book gives a short account on the following items: 1) Metabolism: basic concepts and design specially Stages in the extraction of energy from foodstuffs. 2) Carbohydrates: structure and function. 3) Carbohydrate metabolism: glycolysis, citric acid cycle. 4)Oxidative phosphorylation (electron transport chain). 5)Lipids: structure and function. 6)Lipid metabolism. 7)Calcium and iron metabolism.