And because women often restrict their diet in an effort to control weight, they may not consume enough iron-rich food, and are liable to experience a deficiency. "The average woman takes in only two thirds of the recommended daily allowance of iron," notes another expert. "For a woman who already has a poor iron status, any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency," notes the expert. Exercise can result in iron loss through a variety of mechanisms. Some iron is lost in sweat, and, for unknown reasons, intense endurance exercise is sometimes associated with bleeding of the digestive system.