Technically, a calorie is the amount of heat needed to raise the temperature of 1 kilogram (kg) of water 1 degree Celsius. One calorie is 1/1000 of a kilocalorie (a kcalorie or Calorie). The kcalorie is the unit by which food, and the amount of energy a person takes in is measured. To maintain one's weight, energy intake should equal energy expenditure. If energy intake is negative (if a person consumes fewer kilocalories than he or she needs or expends) then weight loss will occur. If energy intake is positive (if a person consumes more kilocalories than he or she needs and expends), weight gain will occur.
Judith C. Rodriguez