Which macronutrient is essential for long-term, low-intensity aerobic activities?

Fats are the primary macronutrient utilized during long-term, low-intensity aerobic activities. When the body engages in extended periods of moderate exercise, such as walking, jogging, or cycling at a steady pace, it primarily relies on fat stores for energy. This is because during these activities, the oxygen supply is sufficient to metabolize fats effectively, making them a more favorable source of energy for endurance activities.

In contrast, carbohydrates tend to provide quicker energy and are used predominantly during high-intensity exercise or activities that require fast bursts of energy. Proteins primarily serve as building blocks for muscle repair and growth rather than a primary energy source, particularly during aerobic activities. While water is vital for hydration and overall bodily function, it does not provide energy itself and is therefore not considered a macronutrient used for fuel. Thus, fats are key for sustained energy during low-intensity aerobic activities.