Abstract
Classical balance techniques are a powerful, sensitive, and usually accurate technique for assessing the nutritional or metabolic response to changes in nutritional intake or to metabolic or physiological perturbations. Balances are particularly sensitive for examining transient or short-term responses to nutritional or metabolic stimuli. A major factor responsible for the precision and sensitivity of this technique is the precise control of the activities and environment of an individual during a classical metabolic balance study (eg, the carefully defined dietary intake, degree of exercise, and environmental temperature to prevent sweating); these same factors may enhance the precision and sensitivity of other metabolic or nutritional investigations that may be carried out concurrently with a balance study. Finally, for nitrogen balance studies, the measurement of nitrogen (eg, by the Kjeldahl technique) can be very accurate and sensitive.