Final answer:
A 7% body weight loss due to dehydration is a critical threshold that can lead to severe physiological dysfunctions and potentially be life-threatening, thus the statement is true.
Step-by-step explanation:
The statement that a body weight loss of 7% due to dehydration is the most that can be tolerated and still sustain life is true. Dehydration occurs when the body loses more water than it takes in, leading to a negative water balance. This can be a life-threatening condition where vital physiological functions are compromised because water is essential for various body processes, such as digestion, waste removal, blood circulation, and temperature regulation.
When a person experiences a loss of about 2% of total body water, signs of dehydration become noticeable, including thirst, dizziness, and headaches. As dehydration progresses, it can lead to more severe symptoms such as low blood pressure, fainting, and in extreme cases, death. Water loss is exacerbated in situations such as fever, vomiting, diarrhea, and high environmental temperatures, and additional water loss can have severe implications, especially in vulnerable populations such as infants. Therefore, a 7% water loss represents a critical threshold beyond which physiological functions can no longer be adequately maintained, thus putting life at significant risk.