Avert exercise-induced amenorrhea by eating. (Restoring Normal LH Pulsatility).

ST. Louis -- An increase in caloric intake appears to be the simplest way for a woman to prevent or correct exercise-related amenorrhea.

That's because energy deficiency, not exercise "stress," causes the disruption of the reproductive system that can lead to amenorrhea in physically active females, Anne B. Loucks said at the annual meeting of the American College of Sports Medicine.

"Women athletes in general report less dietary energy intake than what would be expected with their levels of activity, suggesting that these women are, in fact, in an energy-imbalanced state," said Ms. Loucks, a biologic scientist at Ohio University, Athens.

Animal and human studies in recent years suggest that a calorie deficit--either from dietary restriction, expenditure of calories through exercise, or both--disrupts LH pulsatiity and triggers bone demineralization, even in females who maintain their normal menstrual cycle, she explained.

Bone demineralization appears to begin after as few as 5 days of low energy availability. Treating amenorrheic women with estrogen and progesterone replacement therapy may not stop the changes in bone formation if the woman remains malnourished, Ms. Loucks said.

Athletes who maintain their normal menses still secrete about half as much progesterone as sedentary women and have a shortened luteal phase. "This luteal suppression appears to be much more widespread than amenorrhea," she said.

Eventually, the process may progress to amenorrhea. At that point, normal menses and normal LH pulsatility can be restored relatively quickly by consuming a sufficient number of calories, even if exercise is continued.