Which dietary fat is primarily used for energy during prolonged, low-intensity exercise?

During prolonged, low-intensity exercise, the body primarily utilizes fat stores, specifically triglycerides, for energy. This is because fats provide a higher caloric yield compared to carbohydrates, making them an efficient energy source for extended periods of physical activity when intensity is lower.

As exercise duration increases, particularly at lower intensities, the reliance on fat metabolism increases. Fats are broken down into fatty acids and glycerol, which can then be oxidized for energy. This process is crucial because glycogen stores—which are primarily composed of carbohydrates—become depleted relatively quickly during exercise.

While carbohydrates are indeed an important energy source, they are mostly used during higher intensity workouts where rapid energy is required. Proteins serve primarily as building blocks for muscle repair and not as a primary energy source during exercise. Vitamins play essential roles in various metabolic processes, but they do not provide energy directly.

Therefore, in the context of prolonged, low-intensity exercise, fat stores are the primary source of energy, highlighting the importance of fat in endurance sports and activities.