describes the amount of fat, bone, water, and muscle in the body

The term that describes the amount of fat, bone, water, and muscle in the body is "Body Composition". Body composition is often measured in terms of body fat percentage, bone mass, water percentage, and muscle mass.

Here are the steps to measure body composition:

1. Bioelectrical Impedance Analysis (BIA): This is a common method for estimating body composition, and in particular, body fat. A small, unnoticeable electrical current is sent from one hand, up to the arm, down to the foot and up to the other hand. The resistance between the electrical flow is what is measured.

2. Dual-Energy X-ray Absorptiometry (DEXA): This is a medical test that involves lying on a table while a machine sends X-rays through your body and measures the difference in the amount of energy initially sent through the body and the amount detected after it exits the body.

3. Hydrostatic Weighing: This method, also known as underwater weighing, compares a subject’s normal bodyweight (outside the water) to his or her bodyweight while completely submerged.

4. Air Displacement Plethysmography (Bod Pod): The Bod Pod measures body mass (weight) using a very precise scale, and volume by sitting inside the Bod Pod.

5. Skinfold Calipers: This method measures the skinfold thickness in several parts of the body, then the results are added up and plugged into a formula that estimates body fat percentage.

Each of these methods can provide a fairly accurate estimate of body composition, but they can also be expensive and require special equipment.