What fraction of the human body's weight is approximately made up of water?

The human body is composed of approximately two-thirds water, which is equivalent to about 66% of total body weight. This percentage can vary based on several factors, including age, sex, and body composition.

In infants, for instance, the water content can be as high as 75-78%, but generally, adult males are around 60-65% water, while adult females tend to be slightly lower, due to higher proportions of body fat. Water plays a crucial role in various bodily functions, including temperature regulation, nutrient transport, and waste elimination. Given the significant physiological importance of water, it's essential to understand how this component factors into overall body weight.

Other options, such as one-half, one-third, or three-fourths, do not accurately reflect the scientific consensus on water's proportion of body weight, making them less representative estimates. Understanding the correct fraction aids in appreciating the importance of hydration and maintaining health.