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
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