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What is RED-S?

Relative energy deficiency in sport, also known as RED-S, occurs when an athlete is not eating enough to replenish the energy they expend during exercise. This can occur inadvertently (busy schedule, not knowing how much food they need, loss of appetite after exercise) or when an athlete intentionally restricts what they eat. When the body does not have enough energy (from food), it will begin to conserve the energy it does have by slowing down or stopping various systems in the body.

RED-S an expansion of the Female Athlete Triad, which previously was used to diagnose female athletes with low energy availability, menstrual dysfunction and low bone density. RED-S includes symptoms of the Female Athlete Triad, but it also encapsulates the broad spectrum of symptoms that can result from low energy availability, regardless of gender.

Health consequences

The health consequences of RED-S are fairly vast. This is because every system in our body relies on the energy we give it through food! Not every athlete with RED-S will experience the full list of health consequences. Below is a list of signs and symptoms that might occur as a result of RED-S:

  • loss of period, irregular period or delayed puberty

  • frequent or nagging injuries

  • low bone mineral density (decreased bone health)

  • decreased metabolism

  • iron deficiency

  • depression/anxiety

  • decreased ability to manage stress

  • frequent or long lasting illness

  • decreased heart health (low blood pressure, low resting heart rate, irregular lipid profile)

  • reflux

  • IBS-like symptoms (bloating, cramping, gas, irregular bowel habits)

Performance consequences

As you can imagine, the health consequences of RED-S can greatly impact performance. This is vastly caused by decreased energy stores, increased risk of injury and illness, and impaired mental health. Below are some common signs and symptoms of RED-S that may be noticeable in an athletes performance abilities:

  • impaired judgement

  • irritability

  • decreased coordination

  • decreased concentration

  • decreased endurance

  • difficulty improving in sport

  • frequently missing practice or performance for illness or injury

  • increased fatigue

  • increased recovery time (ex. feeling sore after a difficult workout for longer than usual)

What does treatment look like?

The team members involved in an athletes treatment will vary depending on the underlying cause(s) of RED-S for that particular athlete. Regardless of the cause of RED-S, an athlete will need to increase energy intake as part of their treatment. Therefore, a Registered Dietitian is most commonly involved, to help the athlete determine the proper strategy for adequate fueling. A physician is also commonly involved to help monitor and treat the athlete's health status. Other team members that may play a role in treatment may include a psychologist, psychiatrist, and/or a physical therapist.

The signs and symptoms for RED-S can look different for every athlete, depending on the cause, their sport, gender and fitness level. If you think you could be at risk for RED-S, or are feeling uncertain about how to fuel for sport, be sure to reach out to a Registered Dietitian.

The bottom line

Unintentional under-eating or restricting food intake can be harmful to both an athletes performance and their physical and mental health. Since RED-S can present differently in everyone, it is important to be aware of the signs and symptoms, and seek out professional help when concerns arise.

Increasing awareness of RED-S is imperative not only for preventative measures, but for early detection as well. Detecting and treating RED-S early on not only saves the athlete from extended stress and struggle, but it also helps reduce the risk of long term consequences.


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