Calories are units of energy. Various definitions exist but fall into two broad categories. The small calorie or gram calorie (symbol: cal) is the approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere.
How many calories should you eat in a day?An average woman needs to eat about 2000 calories per day to maintain, and 1500 calories to lose one pound of weight per week. An average man needs 2500 calories to maintain, and 2000 to lose one pound of weight per week.
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