Carbohydrates are the body's main energy source.They provide the energy needed for all metabolic functions as well as for exercise. The best source of carbohydrates (fruits, vegetables, beans and whole grains) are also packed with vitamins and minerals, fiber and an extensive amount of important phytochemicals.
What are carbohydrates?
Carbohydrates are molecules consisting of three elements: carbon, hydrogen and oxygen. They fuel the body with the energy it needs for the proper functioning of organs.The basic building block of any carbohydrate is a sugar molecule, a simple union of carbon, hydrogen and oxygen.
Starches and fibers consist of chains of sugar molecules (some containing hundreds of sugars).Our digestive system handles all carbohydrates in the same way: it breaks all complex molecules (or tries to) into single sugar molecules, to the extent they are small enough to enter the bloodstream.
Carbohydrates are converted into glucose (also known as blood sugar) and used by the cells for energy purposes.
What are complex carbohydrates?
Carbohydrates are divided into two main categories: simple and complex carbohydrates. Simple carbohydrates (monosaccharides and disaccharides) include simple sugar molecules such as fruit sugars (fructose), corn or grape sugar(dextrose or glucose) or table sugar (sucrose). Complex carbohydrates include all carbohydrates with long chains of monosaccharides (oligosaccharides and polysaccharides).
From a chemical point of view, it makes sense to divide carbohydrates into simple and complex. However, this division is not enough to explain what happens to the different types of carbohydrates in the body.
For example, starches in the bread and potatoes are classified as complex carbohydrates. However, the body converts starches to blood sugar as rapidly as it processes pure glucose. On the other hand, fructose (fruit sugar) is branded as a simple carbohydrate, yet has a minimal effect on blood sugar levels.
Glycemic index foods
This is where glycemic index comes into the scene. Glycemic index (GI) classifies foods based on how quickly they elevate blood sugar levels, taking pure glucose as the comparison point.
Foods with a high GI, such as white bread and white rice, cause a rapid increase in blood sugar levels. On the other side, foods with low GI, such as whole grains and sweet potato, are more slowly digested, causing a lower and gentler fluctuation of sugar levels in the bloodstream.
Foods scoring 70 or more are defined as high GI foods whereas foods scoring less than 55 are considered to be low GI foods. Glucose scores 100 in the glycemic index scale.
Carbohydrates are mainly found in bread, potatoes, pasta, rice and other cereals. Cereal-based foods are also rich in carbohydrates: breakfast cereals, crackers and various pastries. Fruits and legumes, such as beans, also provide a reasonable amount of carbohydrates.