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oxidation, decomposition, and synthesis of fats in the tissues.
the biochemical process by which fats are broken down, incorporated, and used by the cells of the body. Fats provide more food energy (9 kcal/g) than carbohydrates (4.1 kcal/g). Fat catabolism begins with the hydrolysis of fats (triglycerides) into glycerol and fatty acids. Glycerol is converted into a compound that can enter the citric acid cycle. Catabolism of fatty acids continues by beta-oxidation to produce acetylcoenzyme A, which also enters the citric acid cycle. The body synthesizes fats from fatty acids and glycerol or from compounds derived from excess glucose or from amino acids. The body can synthesize only saturated fatty acids; essential unsaturated fatty acids can be supplied only by diet. Fat metabolism is controlled by hormones such as insulin, growth hormone, adrenocorticotropic hormone, and glucocorticoids. The rate of fat catabolism is inversely related to the rate of carbohydrate catabolism, and in some conditions, such as diabetes mellitus, the secretion of these hormones increases to counter a decrease in carbohydrate catabolism.
The sum of the physical and chemical changes involved in the breakdown and synthesis of fats in the body. Dietary fats are digested to fatty acids and glycerol in the small intestine, absorbed, and reformed into triglycerides that are transported in the form of chylomicrons. Fats may be stored in adipose tissue as potential energy or may be broken down to provide immediate energy. The liver has enzymes for the beta-oxidation of fatty acids and their use in the Krebs cycle. Fats may be formed from excess dietary carbohydrate or amino acids. Synthetic reactions produce phospholipids and steroids.
See also: metabolism
fat me·tab·o·lism(fat mĕ-tabŏ-lizm)
Oxidation, decomposition, and synthesis of fats in the tissues.