An understanding of the health consequences of abnormal menstrual function is an important consideration for all exercising women. Menstrual disturbances in exercising women are quite common and range in severity from mild to severe and are often associated with bone loss, low energy availability, stress fractures, eating disorders, and poor performance. The key factor that causes menstrual disturbances is low energy availability created by an imbalance of energy intake and energy expenditure that leads to an energy deficit and compensatory metabolic adaptations to maintain energy balance. Practical guidelines for preventing and treating amenorrhea in exercising women include evidence-based dietary practices designed to achieve optimal energy availability. Other factors such as gynecological age, genetics, and one’s susceptibility to psychological stress can modify an individual’s susceptibility to menstrual disturbances caused by low energy availability. Future research should explore the magnitude of these effects in an effort to move toward more individualized prevention and treatment approaches.