
Originally Posted by
o_Hurley
"Role of Carbohydrates
The roles of carbohydrate in the body includes providing energy for working muscles, providing fuel for the central nervous system, enabling fat metabolism, and preventing protein from being used as energy. Carbohydrate is the preferred source of energy or fuel for muscle contraction and biologic work.
Foods containing carbohydrate are in the grains, fruit, and milk groups. Vegetables have a small amount of carbohydrate.
After carbohydrate is eaten, it is broken down into smaller units of sugar (including glucose, fructose and galactose) in the stomach and small intestine. These small units of sugar are absorbed in the small intestine and then enter the bloodstream where they travel to the liver. Fructose and galactose are converted to glucose by the liver. Glucose is the carbohydrate transported by the bloodstream to the various tissues and organs, including the muscles and the brain, where it will be used as energy.
If the body does not need glucose for energy, it stores glucose in the liver and the skeletal muscles in a form called glycogen. If glycogen stores are full, glucose is stored as fat. Glycogen stores are used as an energy source when the body needs more glucose than is readily available in the bloodstream (for example, during exercise). The body has limited storage capacity for glycogen (about 2000 calories), which is why carbohydrate is commonly referred to as the limiting fuel in physical performance.
Carbohydrate spares the use of protein as an energy source. When carbohydrate consumption is inadequate, protein is broken down to make glucose to maintain a constant blood glucose level. However, when proteins are broken down they lose their primary role as building blocks for muscles. In addition, protein breakdown may result in an increased stress on the kidneys, where protein byproducts are excreted into the urine.
Finally, glucose is essential for the central nervous system. The brain primarily uses glucose as its energy source, and a lack of glucose can result in weakness, dizziness, and low blood glucose (hypoglycemia). Reduced blood glucose during exercise decreases performance and could lead to mental as well as physical fatigue".
This is all pretty basic. I'm only posting it because it seems like a lot of people jump on the no-carb bandwagon without really knowing anything about it.