Theories and assumptions on energy expenditure. Determinations in the clinical setting

Energy metabolism is defined as the sum of complex and integrated chemical reactions by which the body derives energy from the environment and maintains the proper functioning of all biologic processes. The final common pathway for all these processes is the complete oxidation of carbohydrates and fats and partial oxidation of proteins to carbon dioxide and water. These processes occur primarily in the mitochondria and are coupled to the biochemical reactions of the tricarboxylic acid cycle (better known as the Krebs cycle).