How are calorie quantities counted?

Question

How are calorie quantities counted?

Answer 1

A calorie is a unit of energy.  If you're talking about food, a sample is burned completely in a device called a calorimeter (basically a sealed container in an insulated tank of water).  The energy in the food is converted to heat, which warms the water.  From the temperature change you can figure out how much energy was in the sample.  1 calorie (cal) is the amount of energy it takes to heat 1 gram of water up by 1 degree Celsius.  1 kilocalorie (Cal, the kind on food packaging) is 1000 calories.