Clinical needs and opportunities in assessing body composition

Protein-energy malnutrition (PEM) and obesity are hazardous to health with high morbidity and mortality rates. The assessment of body composition is essential to prevent, diagnose and determine the severity of these disorders as well as their response to therapy. Body weight is the sum of fat and fat-free mass (FFM) whereas its chemical model consists of triglyceride, protein, water, and minerals. Thus one must recognize the appropriate method to assess each compartment of body composition. In clinical practice, the method must be simple, accurate, noninvasive and inexpensive. Body mass index (BMI) is a practical anthropometric parameter to assess protein-energy status in adults because it can easily be calculated from weight in kg divided by (height in meter), and correlates with fatness and mortality. Total body fat can be estimated by measuring the amount of subcutaneous fat by measuring the thickness of the subcutaneous fat layer at different sites of the body by a skinfold caliper or near-infrared interactance. A high waist-over-hip circumference ratio (WHR) can be used to diagnose abdominal obesity. Upper arm muscle circumference can be employed to measure muscle mass. However, whenever these methods are used to assess body composition their limitations should be recognized.