Book excerpt: ​This text provides a review of the current knowledge in both the mechanics of nourishing the critically ill and the metabolic and immunological roles nutrients play. In-depth chapters discuss disease-related malnutrition as distinct from under-or-over nourishment and the impact of nourishment in either form of malnutrition. The appropriate timing and indications for nutrition support are provided as well as advanced techniques for improving practice. A broad range of issues related to interdisciplinary practice are addressed. Useful for a wide variety of practitioners, including ICU doctors, hospitalists, and nutrition support physicians, Nutrition Support of the Critically Ill provides practical bedside advice and simplified recommendations for practice.