HUMAN NUTRITION

Detailed explanation-1: -Food energy used to be measured in Calories (Cal) and some countries still use those units. The conversions are as follows: 1 kJ = 0.2 Cal. 1 Cal = 4.2 kJ.

Detailed explanation-2: -Food energy is expressed in calories or joules. A calorie is the amount of energy required at one atmosphere of pressure to raise the temperature of 1 g of water from 14.5°C to 15.5°C (NRC, 1981).

Detailed explanation-3: -A sample of the food is placed in an insulated, oxygen-filled chamber that is surrounded by water. This chamber is called a bomb calorimeter. The sample is burned completely. The heat from the burning increases the temperature of the water, which is measured and which indicates the number of calories in the food.

Detailed explanation-4: -The standard (SI) unit of measure for energy is the Joule (J). This unit derives from the definition of energy, which is the ability to do work. Work is measured also in Joules, which results from multiplying Force (in Newtons) by distance (in meters).