This document discusses body composition monitoring using bioelectrical impedance analysis. It begins by defining body composition as the relative amounts of fat mass and fat-free mass in the body. It then describes several methods for assessing body composition including BMI, circumference measurements, hydrodensitometry, air displacement, skinfold tests, bioelectrical impedance analysis (BIA), CT, PET, MRI and spectroscopy, and DEXA. The document focuses on BIA, explaining its history, principles, limitations, the use of spectroscopy, and types of analyzers including the BCM machine. It concludes by noting factors that should be considered for accuracy when performing BIA tests.