The amount of energy that is needed by a person for cell metabolism, muscular activity, and growth. This energy is provided by the breakdown of carbohydrates, fats, and proteins supplied by food in the diet and by stored nutrients in the liver, muscles, and adipose tissue. Energy is needed to maintain the heartbeat, lung function, and constant body temperature. The rate at which these processes use energy is called the basal metabolic rate (BMR). Any form of movement increases energy expenditure above the BMR. A person’s energy requirement increases during periods of growth and during pregnancy and lactation. When more energy is ingested as food than is used, the surplus is stored and there is usually a gain in weight. When less energy is consumed than is spent, weight is usually lost as the stores are used up. (See also nutrition; obesity.)
Energy requirements |
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