>>76594339
>Food calories are measured using bomb calorimetry by completely burning a dried and homogenized food sample in a sealed, oxygen-rich chamber called a bomb calorimeter, which is surrounded by a known quantity of water.
The sample is ignited with an electric spark, causing it to combust entirely.
The heat released from this combustion increases the temperature of the surrounding water.
The rise in water temperature is measured with high-precision sensors, and the energy content of the food is calculated based on the temperature change and the known heat capacity of the system.
This method, known as direct calorimetry, provides a precise measurement of the total energy or gross energy content of the food, typically expressed in kilocalories per gram (kcal/g) or kilojoules per gram (kJ/g).
You should've learned this shit in high school