The primary energy source of the body is glucose. Glucose is a simple sugar that is a critical carbohydrate in metabolism. It provides energy for bodily functions, including muscle movement, brain activity, and overall cellular processes. When carbohydrates are consumed, they are broken down into glucose, which enters the bloodstream. Insulin then aids in transporting glucose into cells for energy use. In times of prolonged physical activity or fasting, the body can also convert stored energy reserves, like glycogen and fatty acids, into glucose to maintain energy levels. A balanced diet ensures adequate glucose supply for optimal body functioning.