5 Food is composed of chemicals. Those that the body need are called nutrients. Energy is obtained from these materials in the body by controlled combustion, using enzymatic processes to release the energy slowly as heat and work . The process is part of metabolism , and we measure the heat as Calories . We can calculate the approximate caloric value of any food if we know chemical composition.
Table sugar is pure carbohydrate.
Calcium , phosphorus , iron and a few other elements are needed in significant amounts to build body structures such as bones and teeth, molecules such as hemoglobin, and other substances needed for growth and development. The consequences of the lack of building blocks are both physical and mental retardation . Vitamins and Minerals - Fat soluble vitamins, water soluble vitamins, and a number of trace minerals are needed as accessory growth factors in order for our bodies to use energy and building blocks successfully. But to thrive , we need the psychological satisfaction that comes with eating tasty food. Satiety is the feeling of fullness or satisfaction that food conveys, maybe through hormone release from eating.