Mar 16, 2013 – Female runners and other active women who limit their food intake are at an increased risk for menstrual problems and osteoporosis, according to a new study in Medicine & Science in Sports & Exercise.
These adverse health effects are part of what’s call the female athlete triad, three overlapping conditions that include calorie restriction or disordered eating, bone loss or osteoporosis, and amenorrhea (absence of menstruation).
The study is part of a larger investigation called REFUEL, which is looking at the effects of increased caloric intake on menstrual and bone health in active women with menstrual disturbances over the course of a year.
The current study’s findings build on previous research that linked calorie restriction to menstrual problems, but it was the first to examine the relationship between calorie consumption and “low energy availability” in exercising women.
Low energy availability doesn’t refer to your fatigue level. Rather, it is the amount of fuel the body has to function properly. When calories are scarce, the body diverts resources to vital operations like cell maintenance and body-temperature regulation. Since a women’s menstrual cycle is not considered critical to survival, this system slows or shuts down, which can affect estrogen levels and bone health. Low energy availability can be a result of inadequate food intake and/or exercise level—thus the triad.
Energy availability is used as an indicator for potential health risks, so researchers set out to better understand how calorie restriction affects energy availability in active women. After evaluating the food and exercise logs of 87 women and putting them through a battery of lab tests to measure energy and menstrual cycle hormones, the researchers found that the women who ate less (about 1600 calories per day) had lower energy availability and greater frequency of menstrual problems than women who took in 1,900 calories per day. This was not surprising. But here’s what was: women with higher-than-expected energy availability still had menstrual problems.
What does this mean? Mostly, the researchers note, that more research is needed. But it suggests the “energy-availability” threshold that puts women at greater risk for health problems may be higher than the researchers thought, or it may differ for active women than inactive women.
The researchers note that its also unclear how long it takes for a woman with low energy availability to develop mentrual abnormalities and the cause-and-effect relationship between eating behavior and health remains an ongoing investigation.
RUNNERS WORLD: http://www.runnersworld.com/health/what-happens-when-active-women-dont-eat-enough#.UUZMqirmL8Y.twitter