Energy Deficiency: The Female Athlete Triad and Relative Energy Deficiency in Sport (RED-S)

Do you work with athletes who participate in sports that emphasize a lean physique or have weight as a participation factor? These clients have a higher risk of energy deficiency, a condition that can develop easily and lead to irreversible negative effects. Energy deficiency is also a key factor in two medical syndromes affecting athletes: the Female Athlete Triad and Relative Energy Deficiency in Sport (RED-S).

What can you do, as a trainer or rehabilitation professional, to identify energy deficiency and how should this serious health issue be treated?

What Is Energy Deficiency?

Low energy availability (LEA) occurs when an individual does not have sufficient energy to support normal physiological function after the cost of energy expenditure has been removed. For instance, when a female athlete’s energy availability drops below 30 kcal/kg of fat free mass per day, detrimental effects can occur, including perturbation of reproductive function and bone metabolism. In some cases, LEA may be intentional, such as when an individual has a clinical eating disorder, but it can also occur inadvertently due to poor awareness of sport-specific fueling.¹

LEA can lead to chronic fatigue, nutritional deficiencies, and increased risk of infection or illness, all of which have a negative effect on health and performance. LEA also affects cardiovascular risk, psychological stress, and estrogen/progesterone balance, which can lead to an increased risk of stress fractures.²

Energy Deficiency and the Female Athlete Triad

Your clients with Female Athlete Triad will have one or more of the following concerns:

• Low bone density for age
• Menstrual dysfunction, including amenorrhea (no menstrual cycle after age 15 or the absence of three consecutive cycles) and oligomenorrhea (a cycle lasting greater than 45 days)²
• Low energy availability, with energy availability defined as the difference between energy intake and estimated energy expenditure corrected to fat free mass^{1, 2, 3}

Energy Deficiency and Relative Energy Deficiency in Sport

While women are particularly susceptible to energy deficiency, it also occurs in males. In 2007, the International Olympic Committee introduced the term Relative Energy Deficiency in Sport, which acknowledges a wider range of outcomes of energy deficiency and is applicable in both male and female athletes.

RED-S refers to impaired physiological function, including metabolic rate, menstrual function, bone health, immunity, protein synthesis, and cardiovascular health caused by relative energy deficiency.² Male athletes with RED-S may have inadequate nutrition, hypogonadotropic hypogonadism, and/or impaired bone health.³

Currently, there is little research on male athletes and the similarities between RED-S and the Triad, while the Triad has 30+ years of research supporting diagnosis, consequences, and treatment. Future research is needed to establish a standardized method to measure energy availability and identify LEA cut-offs for both male and female athletes.¹

Treating Energy Deficiencies

The Female Athlete Triad Coalition published treatment and return-to-play guidelines for female athletes in 2013.^{4, 5} These include:

• Increasing food intake to meet energetic needs
• Nutrition education from a physician or sports dietitian if the cause is identified to be inadvertent undereating or mild disordered eating
• Referral to a mental health practitioner in the case of more severe disordered eating and clinical eating disorders
• Pharmacological strategies such as combined oral contraceptive therapy, although this should only be considered if after one year nutritional treatment attempts are ineffective for weight gain or reversal of LEA, a reduction in bone mineral density occurs, or a new fracture occurs

While athlete education is a good place to start, an individualized nutrition plan using a comprehensive multidisciplinary approach and including physicians, sports dietitians, athletes, teammates, parents, and mental health professionals is far more appropriate. Additional research is also needed on energy deficiency in male athletes.