Metabolism

Article By:

McCann, Mary B. Nutrition Program, Centers for Disease Control and Prevention, Health Services and Mental Health Administration, U.S. Department of Health, Education and Welfare, Rockville, Maryland.

Last reviewed:April 2019

DOI:https://doi.org/10.1036/1097-8542.417500

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• Metabolism, published June 2014:Download PDF Get Adobe Acrobat Reader

All the physical and chemical processes by which living, organized substance is produced and maintained, and the transformations by which energy is made available for use by an organism. Metabolism encompasses the biochemical processes by which foodstuffs, including carbohydrates, fats, and proteins, are synthesized into complex elements (assimilation and anabolism); complex substances are transformed into simple ones (disassimilation and catabolism); and energy is made available for use by an organism (Fig. 1). In defining metabolism, it is customary to distinguish between energy metabolism and intermediary metabolism, although the two are, in fact, inseparable. Energy metabolism is primarily concerned with overall heat production in an organism, whereas intermediary metabolism deals with chemical reactions within cells and tissues. In general, the term metabolism is interpreted to mean intermediary metabolism. See also: Amino acid metabolism; Carbohydrate; Carbohydrate metabolism; Energy metabolism; Fat and oil (food); Lipid metabolism; Protein

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