Girl athletes’ energy crisis
Stoppage of periods in teenage female athletes stems from hormone imbalance brought on by scant calories
By Nathan Seppa
Roughly one-fourth of high school and college female athletes stop having periods at some point, far more than the 2 to 5 percent rate in women overall, surveys have shown. A new study reveals a hormone imbalance that might help doctors predict girls at risk of losing their monthly cycle.
A stoppage of periods, or amenorrhea, results in temporary infertility and can reduce bone density. Previous research indicates that amenorrhea strikes girls and young women who exercise extensively but have a calorie intake that isn’t adequate to satisfy their bodies’ needs, leading to what scientists call a state of “energy deficit.” Amenorrhea results from internal priorities, enforced by hormones, that allot the athletes’ nutrients. The researchers find that the body’s reproductive system loses out in an evolutionary tug-of-war for calories.
In the new study, researchers studied blood levels of two appetite-regulating hormones, ghrelin and leptin, in 40 female athletes and 18 non-athletic females, all 12 to 18 years old. Roughly half of the athletes had amenorrhea, while the other athletes and the non-athletes still were getting periods. Ghrelin is best known for stimulating appetite and leptin for signaling satiety, but the new study suggests that they also indirectly influence estrogen manufacture and secretion.
The girls with amenorrhea had higher ghrelin levels and lower leptin levels compared with the athletes who were still having periods, says study coauthor Madhusmita Misra, an endocrinologist at HarvardMedicalSchool and Massachusetts GeneralHospital in Boston. That means changes in ghrelin and leptin brought on by a negative energy balance may be important predictors of estrogen levels. Such changes may throw off production of estrogen or other reproductive hormones necessary for having regular monthly cycles, Misra says.