How foods are used by our bodies
Our bodies need foods from different groups to keep us healthy.
Carbohydrates are broken down in the body to become glucose, which gives us energy.
Energy is measured in calories. We all need a certain number of calories each day for energy, even if we aren’t very active. Just sitting in a chair we need energy to breathe. If there are too many calories in our diet we put on weight, and if there are too few we use up our body’s energy stores and lose weight. The amount of energy a person needs each day varies. It depends on how quickly their body uses the energy, and on their level of activity. An adult man needs about 2,500 calories a day and an adult woman needs about 2,000 calories.
Protein is made up of amino acids - the basic element our bodies use to build and repair muscles and other body tissues. The body must have extra protein - as well as extra energy - when we are ill, injured or under stress, to repair any damage.
Fats provide a concentrated source of energy and contain some important vitamins.
Vitamins are essential substances that help our bodies work normally, but we only need tiny amounts of them. If you are eating even a little of the main foods that contain vitamins, you’re probably getting a good enough supply. However, if you’re not able to eat well for a long period of time, you may need a multivitamin to top up your body’s stores. Your doctor, dietitian or pharmacist can advise you about these.
Minerals are substances needed by the body for various functions, such as maintaining healthy nerves and making bones and teeth.
Fibre is sometimes called roughage. It’s the part of the food that passes through the body without being completely absorbed. Starchy foods, such as bread, chapati, cereals, rice, pasta, yams and potatoes, are an important part of a healthy diet. They provide energy and are a major source of fibre, iron and B vitamins. Vegetables and fruit are good sources of fibre too.
Our bodies need a certain amount of fluid each day to work properly. If you don’t feel well it may be difficult to drink enough liquid, but it’s important to try to drink at least 1.5 litres of fluid a day (roughly 8 glasses). This can be water, fruit juice or squash. Drinks that contain caffeine, such as coffee, tea and some fizzy drinks, may make you dehydrated because they make you produce more urine. You can include them in your daily fluid allowance, but have other fluids that don’t contain caffeine as well.