Glycogen is a complex carbohydrate that serves as a key energy reserve in our bodies. It is primarily stored in the liver and muscles, where it can be quickly converted into glucose when energy is needed. This process is especially important during physical activities or when blood sugar levels drop. When we eat carbohydrates, our body breaks them down into glucose, which can be used immediately for energy. Any excess glucose is then transformed into glycogen for storage. When we need energy later, such as during exercise or fasting, glycogen is broken down back into glucose, providing a vital fuel source for our cells and organs.