Many athletes, especially female athletes and participants in endurance and aesthetic sports and sports with weight classes are chronically energy deficient, through a reduction in their energy intake to match their energy output. This may occur intentionally; compulsively; or inadvertently. By reducing their dietary energy intake or by increasing their exercise energy expenditure athletes may lower their energy availability so far that the body's other processes cannot function properly. Because female athletes tend to eat less than would be expected for their level of physical activity, their diet and exercise habits tend to distribute them along a spectrum of energy availability between energy balance and extreme low energy availability. For more information about the conference presentation that I gave in 2008, click here (PDF 1 MB).