The basic facts of calories

A calorie is . . .

A unit of energy. First described in the 1800s, a calorie is technically the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius. But in the health and nutrition world, a calorie is the potential energy in food and the amount of energy the body uses, according to the American Dietetic Assn.'s Complete Food and Nutrition Guide.
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