ST. LOUIS — Women athletes watching their waistlines could be more susceptible to leg pain and stress fractures, according to a small study.

A Saint Louis University study looked at 76 women college athletes playing NCAA Division I sports and found that abnormal and low-calorie eating habits could put them at greater risk for injury.

“It causes people to miss practices and competitions, and I wanted to understand if two people were undergoing the same exercise regime, why only one of them would have leg pain,” said Dr. Mark Reinking, a physical therapy expert who led the study.

“We don’t really know a lot about this in college and high school athletes,” he said. The research was published in this month’s American Journal of Sports Medicine.

The old-school prescription for sore legs — running less or wearing different shoes — doesn’t really help alleviate the pain, Reinking said. Diet appears to be the single most important factor, he said.

The study found that women with “disordered eating,” including bulimia and anorexia, or those who take in too few calories because of dieting, experienced decreased estrogen production, a key factor in bone development, Reinking said.

When people burn more calories than they consume, he explained, they release fewer hormones, which slows down menstrual cycles and decreases estrogen in the body.

“This research is well understood in the medical community,” said John O’Kane, a sports medicine physician and associate professor at the University of Washington in Seattle. “I think that there’s been a lot of work by the NCAA and others to make people more aware of this, it used to be coaches would tell their female athletes, ‘You know you are training hard enough when you stop having your period.’ Today, we understand that (no menstrual cycle) means a calorie deficiency and it can be dangerous.”

Reinking collected survey data on eating behaviors from female soccer, field hockey and volleyball players, as well as cross-country runners. The data included years in school sports, menstrual history, bone mineral density, body-mass index, incidence of prior leg pain and flat feet.

Three-quarters of those athletes in the study had leg pain in the past, especially the cross-country runners, according to the research. Twenty-six percent experienced leg pain during the season, and all of them had had leg pain previously.