During the hospitalization all of the patients will receive conventional nutritional rehabilitation that is composed of serving normal food under supervision of nurses that calculate daily caloric intake through 5-6 meals and according to that additional enteral nutrition that consist of polymeric enteral formula. Daily caloric intake is calculated as kcal/kg/day and is slowly rising through 2 weeks starting from 80% to the goal of 130% of daily energy requirements according to FAO 2004 recommendation.