ABSTRACT
Energy from food is used by the body to fuel muscular activity and for normal metabolism at rest. Obviously, people who are active for a greater proportion of the time use more energy and need to eat more energy providing foods. Fats, carbohydrates, proteins and alcohol are all able to supply energy in the diet. Each provides a different amount of energy per gram, which may be measured either in calories or joules (1kcal=4184kJ). Fat and alcohol are the most concentrated sources of energy, providing nearly twice as much energy as either carbohydrate or protein. This is
clearly shown in Table 18.1 which gives the energy available in different nutrients in both kilogram calories per gram and in kilojoules.
