Metabolic and gastrointestinal alterations associated with trauma can rapidly lead to malnutrition and its accompanying complications. Malnutrition is harmful to the patient because it is associated with impaired wound healing, muscle weakness, immune dysfunction, and infectious complication, and is an independent risk factor for morbidity and mortality. Thus, adequate nutrition support is essential in management of trauma patients. The purpose of this paper is to expound on the metabolic alterations and to provide a rationale for nutrition support in trauma patients.