Which two macronutrients are not dependent on exercise intensity or duration?

The correct choice highlights the relationship between macronutrients and physical activity. Fat and protein are the two macronutrients that do not have their usage significantly altered by exercise intensity or duration.

Fat serves as a primary energy source during low to moderate-intensity exercise, making it a consistent fuel source regardless of the intensity or duration of the activity. Its role remains relatively stable as the body predominantly utilizes fat during prolonged activities, while the reliance on carbohydrates increases primarily at higher intensities.

Protein, on the other hand, is primarily involved in muscle repair and growth rather than immediate energy production during exercise sessions. While it can be used as an energy source under certain conditions, it is not the primary fuel for typical exercise durations, nor does its usage fluctuate dramatically with varying exercise intensity levels. Instead, protein's role is more about recovery and the maintenance of lean muscle mass than about providing energy during exercise.

In contrast, carbohydrates are closely tied to exercise intensity and duration; they are the preferred energy source during higher intensity activities. As exercise duration increases, the body’s reliance on carbohydrate stores also increases until those stores become depleted, leading to a potential drop in performance. Fiber's role is less straightforward in high-intensity exercise contexts, but it primarily supports digestive health