The way we determine the caloric content of food is actually really interesting. It involves equipment called a bomb calorimeter. Essentially, a dehydrated sample of food is placed inside the calorimeter, oxygen is supplied and the sample is ignited. Energy from the combustion is absorbed by the water surrounding the calorimeter and the water's temperature increases. One calorie of energy is defined as the amount of energy needed to heat up 1 gram of water by 1 degree celcius, so as long as you