What substance makes up about 60% of the body's weight?

Water is the substance that makes up approximately 60% of the body's weight. This high percentage is due to the essential role that water plays in various physiological processes. Water is crucial for maintaining body temperature, transporting nutrients, removing waste, and providing the environment for biochemical reactions to take place. In adults, this percentage can vary somewhat depending on factors such as age, sex, and body composition, but it generally hovers around the 60% mark for most individuals.

In contrast, while blood, bone, and muscle each contribute to body weight, they do so to a significantly lesser extent. Blood comprises about 7-8% of total body weight, while bones make up roughly 15% and muscles account for around 30-40%. In comparison, water is far more abundant and is a vital component of all these tissues, linking them together in terms of their physiological functions. Thus, recognizing water's predominant presence in the body highlights its critical importance in maintaining overall health and homeostasis.