During prolonged exercise, what type of energy source does the body predominantly rely on?

During prolonged exercise, the body predominantly relies on fat stores for energy. As the duration of physical activity increases, the metabolic shift occurs from using carbohydrates, which are readily available for short bursts of energy, to utilizing fat as a more sustainable energy source. This transition is due to the fact that fat provides a higher yield of energy per gram compared to carbohydrates and is a more abundant energy source in the body.

During the initial stages of exercise, such as in intense activities lasting only a few minutes, the body primarily relies on glycogen (stored carbohydrates) for quick energy. However, as exercise continues beyond approximately 20-30 minutes, the body’s glycogen stores begin to deplete. At this point, fat oxidation becomes a more significant contributor to energy production, especially in lower-intensity, steady-state activities.

While protein can be used as an energy source during prolonged exercise, it is generally considered a last resort and does not serve as the predominant energy source for sustained activity. Similarly, while sugar reserves (glycogen) and carbohydrate supplements can provide quick energy, they are not primarily relied upon during prolonged exercise due to their limited supply and faster depletion compared to fat stores. Therefore, fat becomes the most efficient and abundant source of energy for the