The main function of the carbohydrates is to act as an energy fuel. Carbohydrates are broken down and converted to glucose relatively fast and therefore provide a fast energy release. Glucose is stored as glycogen in muscle and liver cells and the daily intake of carbohydrate should be adequate to meet the capacity for glycogen storage and should provide around 45 % of the total daily energy intake. When carbohydrates are eaten in quantities that are more then the capacity for glycogen storage it is converted into fat.
When exercising carbohydrates is predominantly the body’s favourite source of fuel and when undergoing moderate intensity exercise on a regular basis the glycogen stores can become depleted. Therefore individual who performs a consistent exercise routine will require a high amount of carbohydrates in their diet compared to those who do not exercise regularly. Training without supervision of a professional fitness trainer you can overwork, which can result in muscle fatigue. With the help of a
personal fitness trainer you can have an exercise routine designed that improves your fitness and avoids overtraining.
Other main role of carbohydrates is to spare protein. When the intake of carbohydrates is low the glycogen stores are depleted and blood glucose levels fall, the body starts to use protein to maintain glucose levels. This causes a loss in the body’s protein stores especially muscle proteins. In extreme cases this can lead to a significant reduction in lean tissue mass and increase the work for the kidneys to expel the nitrogen waste of protein breakdown. Athletes consume a larger quantity of carbohydrate as well as protein after a competition to enable the repair and growth of tissues.
Certain products from carbohydrate breakdown are required for the metabolism of fat. Low levels of these carbohydrate products cause a reduction of fat breakdown while the fats are still mobilised from storage, causing a build up of intermediates (ketones). Ketones have an acidic nature and can lead to high acidity levels in the body fluids (ketosis).
Unlike muscles which use glycogen as well as glucose for energy, under normal conditions the brain uses blood glucose exclusively for energy production and therefore carbohydrates are important for the proper functioning of the nervous system. With a very low carbohydrate intake such as during starvation or a poor regulation of glucose such as in diabetes, metabolic adaptations occur so that the brain uses relatively large amounts of fat for its fuel requirement.
