Many patients will be in pain and have a loss of appetite after surgery.  Part of the body's response to surgery is to direct energy to wound healing, which increases the body's overall energy requirements.  Surgery affects nutritional status indirectly, particularly during the recovery period, as it can interfere with wound healing and other aspects of recovery.   Surgery directly affects nutritional status if a procedure permanently alters the digestive system.  Enteral nutrition (tube feeding) is often needed.  However a policy of 'nil by mouth' for all gastrointestinal surgery has not been shown to benefit, with some suggestion it might hinder recovery.