Define dehydration.

Dehydration is defined as a condition resulting from excessive loss of body water. It occurs when the amount of water lost by the body exceeds the amount taken in, leading to an imbalance that can impair normal physiological functions. This can happen due to various factors such as excessive sweating, illness (like fever or vomiting), inadequate fluid intake, or increased urination.

Understanding dehydration is crucial because even mild levels of dehydration can affect physical and mental performance, leading to symptoms such as thirst, dry mouth, fatigue, and decreased urine output. In more severe cases, dehydration can lead to serious health issues, including kidney damage, heat-related illnesses, or shock.

The other options describe situations that do not accurately capture the essence of dehydration. Conditions like overeating or nutritional deficiencies are related to dietary habits but do not pertain to water balance. A balanced water level refers to hydration, which is the opposite of dehydration. Thus, the definition capturing the essence of inadequate body water is the correct one.