Purpose of review: Body mass index has been shown to be an imprecise measurement of fat-free and fat mass, and provides no information if weight changes occur as a result of a decrease in fat-free mass or an increase in fat mass.
Recent findings: Non-invasive body composition methods (i.e. bioelectrical impedance analysis, air displacement plethysmography) can now be used to monitor fat-free and fat mass with weight gain and loss, and during aging. This review discusses body composition measurements in terms of ethnic differences, physical activity, and age, and the limitations of bedside techniques in obesity and abnormal hydration status.
Summary: An assessment of the fat-free and fat mass provides valuable information about changes in body composition with weight gain or loss and physical activity, and during aging. Non-invasive bedside techniques can now be used to evaluate the nutritional status of healthy and ill individuals.