Carbohydrates are the most important fuel for muscles and the brain. This means that not only do we need carbohydrates to keep energy levels up so we can run, jump, swim and throw, we need carbohydrates to stay focused and maximize reaction time. Our bodies convert all carbohydrates we consume to glucose, also called blood sugar. How quickly this conversion process occurs is dependent on the type of carbohydrate consumed – simple or complex.

Simple carbohydrates include foods that contain table sugar and/or white flour. Examples include, but are not limited to, cookies, candy, ice cream, cake, pretzels, white bread, pasta, soda, sports drinks, many cereals, bagels and fruit.

Simple carbohydrates provide a quick boost of energy, often referred to as a sugar rush, and then an energy dip that can leave you feeling lethargic. Most simple carbohydrates contain very few nutrients such as vitamins and minerals.

One exception is fruit. Fruit is a simple carbohydrate but it also contains healthy nutrients such as fiber, water, vitamins A and C, and potassium. Pairing fruit with protein and healthy fat will round out the nutrient profile of your snack or meal and help keep you satisfied longer. Think about fruit with yogurt or nut butter.

Complex carbohydrates are long chains of sugars that the body digests more slowly and therefore will not raise blood sugar levels as dramatically as simple carbohydrates. Complex carbohydrates provide longer lasting energy as well as fiber, vitamins and minerals. Vegetables and grains are good sources of complex carbohydrates. Complex carbohydrates should be included in most snacks and meals.

Simple vs. Complex

During competitions there may be a place for simple carbohydrate snacks. Complex carbohydrates aren’t available as fuel until about 30 minutes after they are consumed so eating a bowl of rice and beans right before a race will not help fuel your body quickly. A simple carbohydrate snack may be a good option to provide instant energy right before a short event, like a sprint. Simple carbohydrates are also useful as recovery food because when the tank is empty your body is able to utilize it for energy very quickly. When a simple carbohydrate is used as recovery food it should be followed by a well-balanced snack or meal in the next 60 minutes.


The body can only store a limited amount of carbohydrate. It stores carbohydrates in the liver and muscles as glycogen. When we start to move the body begins to break down stored glycogen to maintain blood sugar levels and provide energy for physical performance. We generally have enough stored energy to sustain us for a one day fast or for a few hours of moderate intensity exercise. Once the stores are depleted glycogen needs to be replaced by eating carbohydrate-rich foods.

Kids have limited muscle mass so their ability to store large amounts if glycogen in their muscles is limited. When the body runs out of glycogen it starts to use the protein found in muscle as fuel. Since protein is not stored in muscle tissue the muscle itself starts to break down and muscle mass decreases. Consuming adequate amounts of carbohydrate will allow the body to spare protein and maintain muscle mass.

In kids, when glycogen is depleted their bodies are able to adapt by using fat stores for energy during physical activity. As kids mature, and develop more muscle mass, the potential to store more glycogen increases and their ability to use fat stores as fuel decreases. It is important to be aware that everyone has a different carbohydrate need to achieve optimal performance.