Carbohydrates, or saccharides, are sugars and starches, which provide energy for humans and animals, and cellulose which make up many plant structures. “Carbs,” as they are now commonly referred to, have become both a blessing and a curse, as the process of modern food production has changed the way we consume them. There are two types of carbohydrates, simple, or monosaccharides and complex, or polysaccharides.

Simple carbohydrates, which are found in fruits and dairy products are more easily digested by the body. They are also often found in processed, refined foods such as white sugar, pastas, and white bread.

Complex carbohydrates, which take longer for the body to digest, are most commonly found in vegetables (cellulose), whole grain breads and pasta, brown rice, and legumes. Foods with unrefined grains, such as brown rice, retain complex carbs, unlike refined grains, such as white rice. This is because the refining process removes some of the grain’s fiber and nutrients. Eating a serving of whole grain cereal such as oatmeal will fill you up and give you longer lasting energy than a bowl of sugary cereal due to the way the body processes and uses the carbohydrates.

The liver digests carbohydrates by breaking them down into simple sugars, or glucose, which stimulates the production of insulin in the pancreas. The insulin functions to get the sugar into the body’s cells to be used as energy. The two different types of carbohydrates affect the production of insulin differently—when digesting simple carbohydrates, insulin levels spike faster, and the carbs are used up more quickly for energy. This explains why many who turn to a candy bar for a quick supply of energy find that their energy levels crash when the “sugar high” comes to an end. Complex carbohydrates take longer to digest, resulting in longer lasting energy, and less of an insulin reaction in the body.

If the body produces too much glucose, it will be stored in the liver and muscle cells as glycogen, to be used for when the body needs an extra burst of energy. Any leftover glycogen that isn't stored in liver and muscle cells is stored as fat. The body uses the immediate store of glycogen for short bursts of exercise. For extended periods of exercise such as long distance running and more strenuous workouts, the body will turn to its fat reserve to draw extra energy.

The recommendation of the Institute of Medicine suggests that 40-65% of an adult’s “dietary energy” should come from carbohydrates, while the World Health Organization (WHO) recommends 55-75%. The WHO also recommends that no more than 10% of carbohydrate consumption come from simple carbs.

The body needs a certain amount of carbohydrates to function properly, and insufficient intake may cause fatigue, muscle cramps, and poor mental function. Although carbohydrates are an important part of our diet, the body can produce energy from fat and proteins alone. While this may do for short periods of time, avoiding all carbs will adversely affect your body. Many low-carb diets have been touted as healthy, but if taken to the extreme, they can be very dangerous to a one’s overall well-being. It's important to remember that "low-carb" doesn't mean "no-carb." Be sure to eat moderate amounts of the right type of carbs to keep your body fueled properly.