Exercise dependence, disordered eating and low energy availability

We all know that exercise is good for us. Yet, despite the well-established health benefits of regular exercise, “the too much of a good thing” concept also applies to exercise. Too much exercise coupled with poor calorie intake can lead to a state of low energy availability. Low energy availability occurs when there is not enough calories left over for the body’s normal processes after accounting for the calories expended through exercise [1]. Low energy availability can lead to the syndrome of Relative Energy Deficiency in Sport (RED-S), which can have negative outcomes on both health and performance, such as leading to increased risk of bone stress injuries or underperformance [2,3].

In order to treat RED-S, the underlying cause of low energy availability must be determined. Low energy availability is typically attributed to accidental undereating or disordered eating [2,3]. Both of these situations can lead to low energy availability by impacting calorie intake. However, situations that focus on calorie expenditure need also to be considered. This may include exercise dependence, which is also referred to as exercise addiction [4]. Exercise dependence is likened to other substance abuse and addictive behaviours, such as a gambling addiction [4]. Exercise dependence may occur secondary to an eating disorder, which is known as secondary exercise dependence [4]. In situations of exercise dependence being secondary to disordered eating, exercise is being used for weight manipulation purposes [4].  When exercise dependence occurs in the absence of another pathology, this is known as primary exercise dependence [4]. There is debate if primary exercise dependence is a concern to athlete health [5,6]. However, it is possible that exercise dependence, even in the absence of disordered eating, could lead to a state low energy availability.

My research looked at the relationship between exercise dependence, disordered eating and low energy availability. Below I walk through this publications, but if you want to check out the full article, click here.

How we did it:

To assess the association between exercise dependence and low energy availability, an anonymous online survey was circulated on social media platforms. This survey included validated questionnaires to determine if athletes met the criteria for exercise dependence and/or disordered eating. From this, athletes were classified into one of the four groups:

1. Secondary exercise dependence: These athletes displaying both symptoms of disordered eating and exercise dependence
2. Disordered eating: These athletes only displayed symptoms of disordered eating
3. Primary exercise dependence: These athletes only displayed symptoms of exercise dependence
4. Control: These athletes did not display symptoms of exercise dependence or disordered eating  

To assess for risk of low energy availability in females, we used the Low Energy Availability in Females Questionnaire (LEAF-Q) [9]. As no validated tool is available to assess for risk in male athletes, we instead assessed male responses across the same variables as the LEAF-Q. This included looking at reproductive symptoms, gastrointestinal symptoms, and injury history.

What we found:

We were able to analyze 899 survey responses. The majority of athletes were North American (73%) and competing in Endurance events (84%). Below shows the breakdown of female and male responses across the 4 classification systems. As you can see, only a small number of male and female athletes (2-4%) were classified with primary exercise dependence. This suggests that exercise dependence without disordered eating is not a prevalent concern.

Risk of Low Energy Availability in Females:

Female athletes with disordered eating were 2.6 times more likely than control athletes to be at risk of low energy availability. This was not surprising given that it has long been acknowledged that disordered eating can lead to low energy availability. Interestingly, an even greater risk of low energy availability was seen in athletes with secondary exercise dependence, who were 5.7 times more likely to be at risk of low energy availability. On the other hand, athletes with primary exercise dependence were not at an increased risk of low energy availability.

Symptoms of low energy availability in females:

Similar trends were seen in females when looking at reproductive symptoms, gastrointestinal symptoms, missed training days due to injuries, and previous bone stress factures (See the figure below). Female athletes with secondary exercise dependence had a greater risk of symptoms of low energy availability than athletes with disordered eating. On the other hand, with the exception of a greater risk of bone stress fracture, athletes with primary exercise dependence did not differ from control athletes.

Symptoms of low energy availability in males:

As can be seen from the figure below, like female athletes with primary exercise dependence, male athletes with primary exercise dependence did not have an increased risk of health outcomes associated with low energy availability compared to control athletes. On the other hand, male athletes with disordered eating and secondary exercise dependence had an increased risk of various symptoms of low energy availability.

Differences across competitive status:

We also examined risk of low energy availability, exercise dependence, and disordered eating with competitive status. While we didn’t see a difference in risk of low energy availability and exercise dependence, we did find that athletes competing at the highest level were less likely to be classified with disordered eating. Female international athletes were 46% less likely, male international athletes 66% less likely, and male national athletes 54% less likely than recreational athletes to be classified with disordered eating.

What this means:

1. Exercise dependence without disordered eating does not increase the risk of an athlete developing RED-S. Athletes with primary exercise dependence did not differ from control athletes on most measures, suggesting that exercise dependence without disordered eating does not increase the risk low energy availability. While we did find that female athletes with primary exercise dependence had an increased risk of bone stress fractures, this may have been due to factors beyond calorie intake that can contribute to bone stress injury developing [10]. This may include biomechanical factors or training surfaces.
2. When exercise dependence and disordered eating co-occur an exacerbated risk is seen: Female athletes with secondary exercise dependence had a greater risk of low energy availability and associated health outcomes compared to athletes with disordered eating in isolation. This has important implications for those working with athletes. Screening for and treating RED-S should not only focus on dietary intake, but also an athlete’s psychological relationship with training. Failing to address problematic exercise behaviours in athletes may lead to unsuccessful treatment of RED-S.
3. Disordered eating is not only a concern for female athletes: Male athletes with secondary exercise dependence and disordered eating demonstrated various symptoms of low energy availability. This included reproductive symptoms, gastrointestinal symptoms, and an increased risk of injuries. Evidently, like females, males with disordered eating can also suffer detrimental health outcomes within the RED-S model.
4. Disordered eating isn’t conducive to competitive success:  Athletes competing at the highest level had a decreased risk of disordered eating. This may be due to a selection factor such that disordered eating could preclude success to the highest level of competition. Poor calorie intake could lead to underperformance, and missed training and competition due to injuries. Disordered eating in recreational athletes may go largely unrecognized and easily hidden by training.

Next steps:

While we didn’t find evidence that exercise dependence in the absence of disordered eating increases the risk of low energy availability, future research is needed looking at the impact of primary exercise dependence on other health outcomes. More research is also needed in under-represented groups- this includes more research in males, athletes competing in different sports, and athletes from different countries.

References:

1. Loucks AB, Kiens B, Wright HH. Energy availability in athletes. J Sports Sci. 2011;29:S7-15.

2. Mountjoy M, Sundgot-Borgen J, Burke L, Carter S, Constantini N, Lebrun C, et al. The IOC consensus statement: Beyond the female athlete triad-relative energy deficiency in sport (RED-S). Br J Sports Med. 2014;48:491–7.

3. Mountjoy M, Sundgot-Borgen JK, Burke LM, Ackerman KE, Blauwet C, Constantini N, et al. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med. 2018;52:687–97.

4. Cook B, Hausenblas H, Freimuth M. Exercise addiction and compulsive exercising: Relationship to eating disorders, substance use disorders, and addictive disorders. Eat Disord Addict Subst Use Disord. 2014. p. 127–44.

5. Bamber D, Carroll D, Cockerill IM, Rodgers S. “It’s exercise or nothing”: A qualitative analysis of exercise dependence. Br J Sports Med. 2000;34:423–30.

6. Keski-Rahkonen A. Exercise dependence – A myth or a real issue? Eur Eat Disord Rev. 2001;9:279–83.

7. Hausenblas HA, Downs DS. How much is too much? The development and validation of the exercise dependence scale. Psychol Heal. 2002;17:387–404.

8. Fairburn CG, Beglin SJ. Assessment of eating disorders: Interview or self‐report questionnaire? Int J Eat Disord. 1994;16:363–70.

9. Melin A, Tornberg ÅB, Skouby S, Faber J, Ritz C, Sjödin A, et al. The LEAF questionnaire: A screening tool for the identification of female athletes at risk for the female athlete triad. Br J Sports Med. 2014;48:540–5.

10. Warden SJ, Burr DB, Brukner PD. Stress fractures: Pathophysiology, epidemiology, and risk factors. Curr Osteoporos Rep. 2006;4:103–9.