What is the primary energy source during moderate exercise?

The primary energy source during moderate exercise is carbohydrates. During this level of physical activity, the body utilizes carbohydrates because they can be quickly broken down into glucose, which is readily available for energy production. The efficiency of carbohydrates in providing energy makes them particularly useful for moderate-intensity activities, as they can fuel quick bursts of effort and sustained activity for longer durations.

While fats are also a significant energy source during physical activity, they are typically used more during prolonged, low-intensity exercise rather than moderate intensity, where the demand for instant energy is crucial. Proteins, although important for muscle repair and growth, serve as a secondary energy source and are not primarily relied on during exercise. Vitamins play a crucial role in various bodily functions, including energy metabolism, but they do not provide energy themselves.

Thus, carbohydrates are the most efficient and immediate source of energy for the body during moderate exercise, which is why this choice is the most appropriate.