Although no techniques are currently available that meet the needs of nutrition-support professionals, the future is promising. This article reviews various methods and techniques used to assess the metabolic and nutritional status of surgical patients. Technologic advances in bioengineering, molecular biology, and physiology are providing exciting new tools that may eventually replace or supplement traditional static indices of metabolic assessment. At the very least, an increased understanding of the cellular abnormalities associated with various diseases will likely change our view of illness and our approaches to nutritional and metabolic intervention.