Calculation of energy and energy percentage distribution:

The energizing nutrients carbohydrate, protein and fat provide various food with energy: When we eat, the body "burns" these nutrients and they are converted to energy. This energy is measured in kilojoules (KJ) and in general 1 g. carbohydrate is converted to 17 KJ, 1 g. protein to 17 KJ and 1 g. fat to 38 KJ, (according Atwater´s figures).

An example: If you want to calculate the energy content in milk, do it this way:

Protein:            3,4 g x17 kJ = 57,8 KJ

Carbohydrate:  4,8 g x 17 kJ = 81,6 KJ

Fat:                  1,5 g x 38 kJ = 57 KJ

Total                                    = 196,4 KJ

(The packaging shows how many grams of the various nutrients there are per 100 g. of the food).

It means that when you drink 100 g. of milk, your body converts the nutrients to 196,4 KJ of energy.

The energy percentage distribution is then:

Protein:           (57,8/196,4) x 100 = 29 %

Carbohydrate: (81,6/196,4) x 100 = 42 %

Fat:                    (57/196,4) x 100 = 29 %

When you drink this milk 29% of the energy is from protein etc.