The human body is an amazingly complex and wonderful ‘machine’, but it cannot function without a supply of food. The nutrients in food are needed for energy, movement, heat, growth, repair, general maintenance and sometimes reproduction. The body needs to be able to digest the food it takes in so that it can be used in various ways. Some foods have to be processed into more basic kinds of food or treated chemically within the body. Others do not require such elaborate processing and some pass through the body almost unchanged.
The key to a sensible diet is to eat the right mixture of foods to ensure sufficient nutrients, but it should also be related to the life you lead. Generally speaking most foods contain several nutrients in varying amounts. There are six basic types of nutrients and two basic non-nutrients found in food. The six nutrients are carbohydrate, fat, protein, vitamins, minerals, trace elements; the two non-nutrients are fibre and water.
Carbohydrates are needed to provide energy and help keep the body warm. By processing carbohydrate the body can produce heat and so be able to work and move. Excess carbohydrate can be made (by the body) into fat and stored for future use.
Fats are another source of energy for the body, even more concentrated than carbohydrate. Again, excess of this nutrient can be stored as body fat for future use as an energy provider.
Proteins are needed for repairing damage and growth. The body is able to convert excess protein into energy and heat as it does with carbohydrate.
Vitamins, minerals and trace elements are necessary for the efficient working of the body. As you will see later in this book, there are many of them and they have special jobs to do in the body.
Water and fibre, although not classed as nutrients, are nevertheless very important. Water is absolutely essential for life and while the body can survive for a limited time without food, it must have water or it cannot function. Fibre is not considered to be essential, but without it life for the human body can be extremely uncomfortable.