Critically ill patients are often hypermetabolic and can rapidly become nutritionally compromised. Malnutrition is prevalent in these patients and has been associated with increased morbidity and mortality. Standard nutrition therapy, i.e. provision of calories, protein and other nutrients consists primarily of enteral nutrition (via a feeding tube into the gastrointestinal tract), parenteral nutrition (via an intravenous tube into the blood), or occasionally a combination of both.