Health consequences of low energy availability in female athletes

Ackerman RED-S female athletes energy deficiency sports

For all young athletes, having the necessary energy to participate in sports — while also supporting a growing body — is imperative to their overall health. The Female Athlete Triad is a well-known consequence of low energy availability in female athletes and can result in menstrual dysfunction and decreased bone mineral density.

Recently, the focus has turned from the Triad to a more inclusive term; Relative Energy Deficiency in Sport, or “RED-S.” This syndrome also appears to be a result of low energy availability, but has health consequences other than menstrual dysfunction and bone health in females and acknowledges that relative energy deficiency can happen in males.

The International Olympic Committee (IOC) has developed two RED-S models, which include 10 health consequences and 10 performance consequences. To determine the viability of these models, Kathryn Ackerman, MD, MPH, director of the Female Athlete Program at Boston Children’s Hospital, has published a study examining the association between low energy availability and the health and performance consequences of RED-S in female athletes. This 1,000-patient study was a companion paper to the British Journal update on the IOC’s RED-S concept, of which Ackerman was a co-author.

Energy availability and study parameters

Energy availability (EA) is defined as the amount of dietary energy remaining after exercise and available for other physiological functions, such as growth, muscle recovery and homeostasis. The IOC’s RED-S models describe the imperative role energy availability plays in the health and performance of both male and female athletes.

For Ackerman’s study, female athletes between 15 and 30 years old who averaged four or more hours of physical activity per week were recruited. All participants in the study were being treated at Boston Children’s sports medicine clinic for various conditions.

Participants answered an online questionnaire to determine whether they were at risk of low energy availability, and if there were potential physiological or performance consequences associated with low EA. An individual was determined to have low EA if she had a positive response to one or more of three disordered eating screens. Other questions involved general health, illness, injury, sports performance and Triad/RED-S risk factors. These questions were formulated to address aspects of the 10 RED-S health consequences and eight of the 10 performance consequences proposed by the IOC.

The RED-S results

Pertaining to health consequences, female athletes with low energy availability were:

  • 3x more likely to suffer metabolic issues
  • >2.5x more likely to have cardiovascular issues
  • 2.4x more likely to report a history of psychological issues
  • 1.6x more likely to report a history of hematological issues
  • 1.5x more likely to have gastrointestinal issues

For performance consequences, female athletes with low energy availability were:

  • 2.1x more likely to have an increased recovery time
  • 4.3x more likely to report judgement impairments
  • 1.6x more likely to report feeling uncoordinated
  • 2x more likely to have difficulty concentrating
  • 1.6x more likely to report feeling irritable
  • 2.3x more likely to suffer feelings of depression
  • 1.5x more likely to feel a decrease in endurance during sports and/or training

Along with the menstrual dysfunction and decreased bone health that are part of the Triad, the results of Ackerman’s study show that there are a multitude of other health and performance factors associated with low energy availability.

Additional findings

One of the more concerning findings of this study was that almost half of all female athletes surveyed screened positive for features consistent with low EA, according to the study’s criteria. “It certainly was surprising that the numbers were that high,” says Ackerman. “But it brings light to the situation that a lot of female athletes are struggling with body image, dieting and the pressures of how they’re supposed to appear as athletes. Hopefully this study can bring attention to these issues.”

Another interesting finding was that the mean body mass index (BMI) was in the normal range for both the low EA and adequate EA groups, but slightly higher in the low EA group. While counterintuitive, this illustrates that low energy availability isn’t always visible to a clinician’s eye.

“Extremely low BMI is a warning sign in and of itself, but it doesn’t mean that people with normal BMIs aren’t at risk,” says Ackerman. “PCPs, sports doctors and pediatricians should be routinely asking female patients about menstrual history, as that can be used as a vital sign of the Triad and RED-S conditions.”

Additionally, physicians should be encouraging young female athletes to properly fuel themselves for performance — putting emphasis on “strong” over “thin.” It can be difficult to have a young athlete understand the consequences of an unhealthy or insufficient diet, but Ackerman believes the findings of her study can be used to educated female athletes.

“I think the other positive part of the RED-S concept is that athletes will latch onto some of these additional consequences more. Bone density sounds like such a distant problem, even if it might not be for them, but when you tell them it’s detracting from their athletic performance, or it’s affecting cardiovascular function, or relating to their gastrointestinal complaints, sometimes it makes the athlete listen more. If you can list off a lot of different consequences, something might eventually click, encouraging athletes to take advantage of treatment resources and modify behaviors.”

Learn more about the Female Athlete Program at Boston Children’s Hospital.