ABSTRACT
The composition of the human body can be assessed at several levels. As briefly discussed in Chapter 1, body composition can be assessed at the elemental level. Here oxygen, hydro gen, carbon, and nitrogen are recognized as the greatest contributors to human mass. This is easily understandable, because these four elements are the primary atomic building blocks for key organic molecules and water (Table 12.1). Next, human body composition can be assessed at the molecular level, with minerals grouped together to represent that which is not molecular. For instance, in a lean adult male, water provides about 60% (56 to 64%) of his mass, and both protein and fat will each account for roughly 15 to 16% of his total mass (Table 1.2). About 4 to 6% of human mass can be attributed to minerals while the remaining 1% or so is attributable to substances like carbohydrates and nucleic acids.
