Food energy is the amount of energy obtained from food that is available through cellular respiration.  Fiber, fats, proteins, organic acids, polyols, and ethanol all release energy during respiration — this is often called “Food Energy”. Each food item has a specific metabolizable energy intake (MEI). Normally this value is obtained by multiplying the total amount of energy associated with a food item by 85%, which is the typical amount of energy actually obtained by a human after respiration has been completed. About twenty percent of the energy is used for brain metabolism, and much of the rest is used for the basal metabolic requirements of other organs and tissues

Many governments require food manufacturers to label the energy content of their products, to help consumers control their energy intake. Like other forms of energy, food energy is expressed in calories or joules. European Union, manufacturers of prepackaged food must label the nutritional energy of their products in both kilocalories and kilojoules, when required. In the United States, the equivalent mandatory labels display only "Calories“ Recommended daily energy intake values for young adults and men are: 2500 kcal/day and 2000 kcal/day for women. Children and older people require less energy

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