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Low energy availability - what, why & how to avoid

Relative energy deficiency in sport (RED-S) is a syndrome that results in impaired physiological functioning. It is underpinned by low energy availability (LEA). LEA is a mismatch between an athlete’s energy intake and the energy expended in exercise, leaving inadequate energy to support the functions required by the body to maintain optimal health and performance (Mountjoy et al, 2018). LEA forces the body’s systems to adapt to lower energy levels, which compromises and reduces the energy available to the body for key functions such as bone health, reproduction, and immunity. This increases the risk of multiple health problems.

The female athlete triad has in recent times more commonly been referred to as RED-S. There are several reasons for this change including the significant number of physiological consequences of this condition are not just limited to abnormal menstrual cycles and bone health and RED-S incorporates these factors. Whilst it is thought that the incidence of LEA is higher in females than in males (Mountjoy et al, 2018) athletes of either gender can suffer from this condition.

LEA is more common in athletes involved in specific sports. These include: individuals who participate in sports that are endurance based ie distance running and triathlon; sports where lean or light body types are often considered good for performance ie cycling, running, rowing, gymnastics as well as sports where a weight category is implemented for competition ie weightlifting and combat sports.

There may be practical contributions towards LEA also including inadequate food availability, food insecurity and lack of financial resources and time for food preparation. Importantly LEA can occur with any body type, at any body mass and in both men and women.

Commonly LEA is the result of accidentally not meeting the energy needs of their sport, exercise activity or daily life. An increase in training volume without increasing dietary energy intake, a lack of food preparation or eliminating food groups can all increase your risk of suffering from LEA. A lack of knowledge or understanding of nutrition, being influenced by the eating habits of others and social media dietary trends may also contribute. There is a continuum from accidental LEA to disordered eating where eating patterns are deliberate to result in a set outcome.

One of the significant challenges in diagnosing LEA is the accuracy of self-reported energy intake. Energy expended, total energy intake over the day, as well as the frequency of eating throughout the day are all important contributors to the development of LEA.


Some of the signs to look out for as indications LEA may be present include frequent or repeated illnesses, recurring injuries that don’t get better eg stress fractures, tired or not recovering from training, absent or irregular menstrual cycles, poor concentration, reduced interest and low mood along with underperforming in training and competition. LEA is not always accompanied by weight loss. Weight is therefore not a great guide on its own to the presence or absence of LEA.

The science

The hypothalamus and pituitary gland are areas of the brain that produce hormones. These hormones affect how the ovaries work and are critical in having a normal menstrual cycle. Altered hormone levels of LH (Leutinising hormone) and FSH (Follicular stimulating hormone) result in alterations to the menstrual cycle. This may result in oligomenorrhea (3 – 9 periods per 12 months or the length of a cycle more than 35 days) or amenorrhea (absence of a menstrual cycle). If either of these issues are present differential diagnoses such as polycystic ovaries should be ruled out by physicians prior to LEA being confirmed. The most common cause of amenorrhea or oligomenorrhea in athletes is functional hypothalamic amenorrhea (FHA). This is when a woman’s body isn’t producing hormones as expected and therefore periods are affected. In athletes, this usually results from not having enough energy intake for the amount of exercise being performed. When athletes are on the oral contraceptive pill (OCP) this is masked, and LEA is difficult to diagnose although may be suspected. For this reason, if an athlete is at high risk of developing LEA alternative contraceptive options should be considered such as an IUD (intra-uterine device). A regular menstrual cycle in an athlete is a sign of health and therefore alterations to this must be monitored.

Iron deficiency is often seen in female athletes and can be linked to the cause and effect of LEA. Growth may be affected in athletes with LEA over prolonged periods of time during their growth phase. In addition to this there can be effects on the gastrointestinal, immunological, and cardiovascular systems, as well as psychological effects. There are reported performance consequences of low energy availability. There is often a “tipping point” where LEA becomes so significant that performance is affected. Prior to this, athletes may report a period where performance remains high although they are in a state of LEA. This may be related to power to weight ratios for their sport. Unfortunately, once performance is affected it is a long road back for many of our athletes to return to a healthy state where they may begin to return to their previous sporting performance. Educating athletes regarding this can be a challenging task particularly in sports where low body fat is “idealized” for performance.


Treatment for LEA is multidisciplinary and will involve a doctor and nutritionist along with the involvement as appropriate of other medical professionals such as a physiologist and psychologist.


The prevention of LEA includes a well-balanced diet that provides enough energy to support the demands of exercise and life allowing for optimal health, training adaptation, recovery and performance. When there is an increase in training volume or intensity, energy intake should increase to match the increase in energy expenditure. Education of athletes so they understand the energy value of food and the demand of exercise ensures they are able to proactively ensure they maintain appropriate energy intake. Be cautious of information online particularly in social media and seek help early if there is any alteration in their menstrual cycle.

A monthly barometer of female health

The average age in NZ for females to get their first period is 13 years old. Generally, within 2 years of onset they should have a regular menstrual cycle. If they do not have a menstrual cycle by 15 years of age, they have delayed menarche and should see a Doctor for investigation. Athletes often think that missing a period is normal, but we know this is not normal nor optimal from a health, recovery, or performance perspective. Recent research in our elite and development high performance athletes in NZ suggests up to 50% of athletes have or have had menstrual cycle dysfunction with over a quarter suffering from one or more stress fractures which is integrally linked to LEA. Up to ¾ of these athletes also reported pressures felt around the ideal body image and the issues this presents for the health of them as the athlete. This research also confirmed some of the previously identified barriers to preventing LEA such as difficulty communicating with male coaches and support staff regarding this topic, lack of education regarding women’s health, social media, and sponsors as specific areas of pressure.

In summary having a regular period is a visible sign of good hormonal health and energy balance. Having regular periods is a good guide to the readiness for training and performance. If an athlete’s menstrual cycle has changed or does not fit with the expected pattern a General practitioner (GP), Sports Doctor or Sport Medical Director should be consulted. REMEMBER whilst this article is primarily written about female athletes LEA can occur in both males and females so as medical professionals, we should be aware of the risk factors, the signs and symptoms that may be present and when we need to refer for further investigations.

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