What is a common side effect of consuming excessive protein?

Consuming excessive protein can lead to dehydration, primarily because the metabolism of protein requires more water to process the nitrogen found in amino acids. When protein intake exceeds the body's needs, the kidneys must work harder to eliminate the excess nitrogen, resulting in increased urine output. This can lead to a net loss of fluids and, consequently, dehydration if adequate water intake is not maintained to compensate for this increased demand.

The other options do not accurately represent side effects of excessive protein consumption. Improved hydration is contrary to the effect of dehydration. Enhanced energy is not a direct consequence of high protein intake; in fact, carbohydrates are typically the main source of energy for exercise. While increased muscle mass can be a result of adequate protein consumption when paired with resistance training, it is not a side effect, especially when protein is consumed in excess without accompanying exercise. Thus, dehydration is the correct and relevant outcome of excessive protein intake.