Undernutrition is a state marked by energy and/or protein intake deficiency or mal-absorption, and is often described as protein energy malnutrition (PEM). Malnutrition is common in hospitalized patients worldwide. The prevalence of malnutrition in hospitalized patients range from 20% - 50%, depends on the varieties of diseases, health system, population and assessment tools. It is well documented in Western countries that malnutrition affects clinical outcomes negatively. Compared with well-nourished patients, patients with malnutrition stay longer in hospitals and related cost is significantly higher.