There seems to be a whole lot of confusion regarding the definitions and differences between Simple Carbohydrates and Complex Carbohydrates, not to mention what the actual functionalities are in general.

Carbohydrates, protein and fat are the three micronutrients that provide calories in our diet, however carbohydrates actually provide more energy than the other two sources of calories thus contributing to normal life functions such as digestion, heartbeat, and breathing. Many athletes consume a diet rich in carbohydrates because of the digestible energy that this form of nutritional intake contributes to the body. Simply put carbohydrates convert to glucose (blood sugar) whether simple or complex, at a rate of four calories per gram even though the chemical structure between the two forms of carbohydrates differ.
Simple Carbohydrates are more rapidly digested and thus become energy more quickly. These are good for that quick burst of energy or “sugar rush” however, simple carbs are lacking in vitamins and minerals so while they can provide a necessary jolt of energy, they are lacking long term nutritional value. High sugar calories are not only nutritionally empty, but can lead to weight gain, moodiness, withdrawals, uneven up and down energy levels and cravings. Some examples of simple carbohydrates include sugar, some less fibrous fruits, fruit juices, milk, yogurt, honey and molasses.

Complex carbohydrates break down slower in our blood stream, providing a longer energy band plus most complex carb rich foods are packed with fiber, vitamins and minerals which makes them much more beneficial, overall, to our nutritional balance. Since many of these foods are high in fiber, they are helpful to the overall digestion and conversion of calories to energy and these calories tend to breakdown slowly, into a more sustainable energy which in turn helps to prevent cravings and the associated negative issues with energy ups and downs. Some examples of Complex Carbohydrate rich foods include pasta, legumes, cereals (be careful of the sugar content), breads, vegetables and fiber rich fruits. 
Most dieticians and nutritional experts suggest that up to fifty or sixty percent of a person’s total dietary calories should be derived from carbohydrates and further, that those carbohydrates consumed should largely be those of the complex nature since they have more nutrient value in general than the calories attained by consuming most forms of simple carbohydrates.

In recent years, low carbohydrate diets have gained in popularity due to concerns about unhealthy side effects of simple carbohydrates. This has been associated with increased risk of diabetes, cardiovascular issues and in some research, even breast cancer. However, carbohydrates are very beneficial for brain function so it is important to differentiate between the two forms of carbohydrates and utilize complex carbohydrates in a balanced diet.

When it comes to carbohydrates it is essential to be a smart consumer and read the labels on the foods you are purchasing. Avoid foods that are overly processed, have sugar, sucrose, fructose, corn syrup, processed white or wheat flour at the top of the ingredient list and instead choose products with whole grains. Make simple changes in your dietary intake like choosing fresh fruit instead of fruit juice, oatmeal instead of processed, sugary, packaged cereals for breakfast. A good rule of thumb is that the more whole the food, the less processed it is, the better it is for you. Balancing carbohydrates, fat and protein is essential to a healthful diet, so stick with 5 servings of complex carbohydrates per day while cutting back on the simple carbohydrates.