Carbohydrates are high-quality fuel food because compared to proteins or fats, the body need a relatively little work to break them down in order to release their energy. The idea that carbohydrates are fattening is only true when they are consumed with fatty additions or are eaten in quantities much larger than the body can readily use; because carbohydrates in their natural state are also low in calories and high in fiber, vitamins, and minerals.

Two Groups of Carbohydrates:

• Simple carbohydrates or sugars are more refined and are usually found in foods with fewer nutrients, and tend to be less satisfying and more fattening. They are also rapidly converted into glucose to provide energy. Examples of simple carbohydrate are table sugar, corn syrup, fruit juice, candy, cake, bread made from white flour, pasta made from white flour, baked goods made from white flour, packaged cereals and colas.
• Complex carbohydrates are high fiber foods, which improve your digestion. They help stabilize the blood sugar, keep your energy at an even level, and help you feel satisfied longer after your meal. Examples of complex carbohydrate are vegetables, fruits, whole barley, buckwheat, brown rice, oatmeal, potatoes, and beans.

Glycemic Index or GI is a measure of the effects of carbohydrates on blood sugar levels. Carbohydrates that break down quickly during digestion, releasing glucose rapidly into the bloodstream, have a high GI while carbohydrates that break down more slowly, releasing glucose more gradually into the bloodstream, have a low GI. The bigger the particle size, the more difficult it is to digest and the more slowly glucose is released into the bloodstream, yielding a "lower glycemic index." For example, stone-ground whole grain bread has a larger particle size, and a lower glycemic index, than finely milled bread, whether white or wholegrain. Similarly, raw whole apples have a lower glycemic index than pureed apples.

How carbohydrates work in the body? The human body metabolizes both simple and complex carbohydrates into glucose, or blood sugar, the body's primary source of fuel. Glucose is essential for the functioning of the brain, nervous system, muscles, and various organs. Any glucose that is not needed for immediate energy is converted into glycogen and stored in the liver and muscles; when it is required, the liver turns the glycogen back into glucose.

Exercise and Carbohydrates: Regular exercise increases the body's ability to use glucose efficiently and to store glycogen in muscle tissue. Thus, the fitter you are, the greater your ability to store the extra glycogen that is particularly needed for endurance events, such as running and cycling.

What happened if the body's supply of carbohydrates is depleted? When carbohydrates reserve run low, the body turns first to protein and then to fat to convert them into glucose. Burning protein, however, robs the body of lean muscle tissue. In addition, if the body has to burn fat in the absence of carbohydrates, toxic by products called ketones are released; these can lead to a potentially dangerous biochemical imbalance.

Note: Just because you don't see "sugar" listed as an ingredient on a food label doesn't mean it's not there. Look for words ending in "ose" (sucrose, lactose, maltose, fructose and dextrose) and anything describes as "syrup" (such as corn or malt syrup), as well as honey and molasses.