Final answer:
Upper arm circumference most accurately correlates with the body's total protein stores, as it accounts for both muscle mass and subcutaneous fat, providing a good estimate of protein reserves.
Step-by-step explanation:
The correlation of body protein stores with different physical parameters can delineate the best indicators of nutritional status. Skinfold thickness, using calipers, is a commonly employed method to measure body fat and indirectly assess total body protein. However, upper arm circumference is considered a more reliable measure for assessing the protein reserves in the body than height, weight, or skinfold thickness. Upper arm circumference takes into account both the muscle mass (which contains the majority of the body's protein) and subcutaneous fat, offering a better approximation of body protein stores.
Measuring upper arm circumference provides a noninvasive and fairly accurate method for estimating the muscle mass component of body protein stores. Measuring fat distribution is also important, and techniques like the waist-to-hip ratio can provide insight into health risks associated with obesity to complement body protein estimates. However, this waist-to-hip ratio is more focused on fat distribution rather than total protein reserves.