Body composition refers to the proportions of the body made up of fat and fat-free mass. Several methods are available to measure body composition. Skinfolds and Bod Pod assessments are performed at the Student Recreation Center at the University of Alabama. The Exercise Physiology Laboratory features underwater (hydrostatic) weighing, bioelectrical impedance analysis, and the three-compartment model for body composition assessment.
Underwater weighing is an accurate and reliable method of body composition assessment. Those wishing to undergo this assessment must be comfortable in water.
Bioelectrical impedance analysis (BIA) is less accurate than underwater weighing but compares favorably to skinfold assessment of body composition when normal hydration status is assured. BIA assessment requires the individual to be normally hydrated and lie quietly on a bed while measurements are made.
Three-compartment model (3-C) is a reliable method of body composition assessment considered more accurate than the methods listed above because it accounts for daily fluctuations in body water that can introduce error to the other two methods. The 3-C method involves measuring body volume using underwater weighing and total body water using bioelectrical impedance. Information from the two methods is then combined to determine body fat percentage. Those wishing to undergo this assessment must be normally hydrated and be comfortable in water.