Severity of energy-related menstrual disturbances increases in proportion to indices of energy conservation in exercising women.

Alterations in resting energy expenditure and metabolic hormones (energy conservation) are evident in increasing magnitude across a continuum of increasing severity of clinical menstrual disturbances, including luteal-phase defects, anovulation, and amenorrhea in exercising women. These data provide further evidence of the tight association between energy balance and reproduction and suggest that subtle declines in energy availability can produce clinically recognized menstrual disturbances.