Why do only high-performance athletes typically require carbohydrate and protein intakes above general dietary guidelines?

Because their repeated high-intensity training requires much larger glycogen stores and greater muscle repair and synthesis demands compared with typical daily activity levels.

Because general guidelines are intentionally set low to discourage all physical activity unless athletes train professionally, and only athletes are permitted to exceed them for performance reasons.

Because non-athletes cannot metabolize the extra carbohydrate and protein efficiently, so extra intake would be wasted regardless of exercise level.

Because high-performance athletes have chronically lower resting metabolic rates which force them to increase intake of carbs and proteins to maintain body weight.