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RED-S Consequences

Beneath the surface

In 2018, Margo Mountjoy, described RED-S among the athletics population as the tip of an iceberg: its true magnitude is largely hidden and its devastating impact, underestimated. The same analogy can be applied to the consequences of the condition, where the tip of the iceberg represents the visible warning signs (the injuries, illnesses, low moods, disrupted sleep) and the dangerous part lies beneath the surface (the mass of physiological and psychological consequences that build up over time).

The International Olympics Committee consensus statement describes how RED-S causes impaired physiological function across almost every single system in the body, including: the metabolic, immune, cardiovascular, nervous, digestive, muscular, reproductive and skeletal system. Not only are the knock-on implications detrimental to an athlete's overall health, but inevitably, all elements of their sports performance. We've summarised these below, in the hopes that a peek beneath the surface of the problem might inspire the changes required to reverse them.


Performance impacts include:

  • Decreased power, muscle strength and stamina
  • Decreased response to training/poor recovery between sessions
  • Increased risk of injury, illness and infection
  • Impaired cardiovascular and respiratory adaptations
  • Impaired judgement, coordination and concentration

General health impacts include:

  • Decreased immunity and increased risk of illness and infection
  • Delayed healing time from injury and illness
  • Hormonal abnormalities - menstrual disturbances including hypothalamic amenorrhea (missing periods) among females and erectile dysfunction among males
  • Metabolic disturbance - decreased metabolic rate and reduced production of human growth hormone
  • Cardiovascular issues - valve abnormalities, arrhythmias and increased risk of coronary artery disease
  • Haematological issues - increased risk of low ferritin and iron deficiency (anaemia)
  • Gastrointestinal disturbances - impaired absorption of nutrients/nutrient deficiencies (e.g iron, Vitamin D, B12, folate)
  • Decreased bone density - increased fragility of bones and increased risk of osteoporosis
  • Low moods, low self-esteem, depression and anxiety

While none of these consequences occur in isolation and they are all equally important to recognise, we've expanded on a few that are particularly concerning for many athletes with RED-S.

Bone health

Aside from supporting you to train for the sport you love, bones are active, living structures which constantly rebuild and repair. When in a state of RED-S, this process is hindered by the same suppression of hormones that causes menstrual dysfunction, alongside the nutritional deficiencies (e.g. calcium and vitamin D) that accompany an energy deficit.

The result is a major cause for concern - especially for young female athletes - since 60-80% of lifetime bone mass is formed by age 18 and peak bone mass achieved by 26-30. In the long-term, the potential implications of RED-S include an inability to reach peak bone mass for young athletes and irreversible bone loss for older athletes. Where menstrual dysfunction is concerned, for every year an athlete spends in a state of amenorrhea (see below), bone mass is estimated to decrease by 2-6%.

Bottom line: RED-S causes impaired bone development and repair, leading to increased risk of stress fractures and osteoperosis. Loss of bone density can be an irreversible implication of RED-S. You only get one set of bones in this life; protecting them now is a priority.

Mental health

We can't talk about the consequences of RED-S without addressing mental health. Whilst it can be difficult to determine whether the myriad of adverse psychological implications of RED-S precede the problem, or are the product of it, they can incude: low self-esteem, low motivation, feeling a loss of control, difficulty concentrating, distorted body image, feeling overwhelmed, feeling stressed, feeling detached from peers or societal groups, anxiety, depression. One further crucially important psychological effect of an energy deficit surrounds an inability to recognise the risk of developing RED-S.

Bottom line: The psychological implications of RED-S deserve a website of their own. They can be plentiful, frightening, powerful and debilitating. The thoughts, feelings and emotions alone can be enough to prevent you from taking steps to change your situation. But importantly, the longer the physical energy deficit is maintained, the stronger the fears and negative emotions surrounding your situation are likely become. Don't let them stand in the way of your recovery. Now is the time to take action.

Menstrual health

RED-S has a direct negative impact on the reproductive system which regulates the menstrual cycle. As briefly explained here, menstrual disruption includes hypothalamic amenorrhea (HA) which describes loss of a menstrual cycle. This is three times more likely to develop among female athletes than non-athletes and the consequences of this are serious and extensive, including: infertility, decreased bone density, reduced cognitive function and coping ability, increased likelihood of mental and physical illness, increased risk of developing soft tissue injuries, gut distress, fatigue, and impaired rate of recovery.

Does it matter if you’re on the Pill?

One of the biggest barriers to understanding your natural menstruation status surrounds use of the Oral Contraceptive Pill (the Pill). While many athletes are inappropriately advised about using the Pill to compensate for their menstrual dysfunction, they are absolutely no substitute for a natural period. The artificial imitation of a period produced by the Pill (the withdrawal bleed) only serves to mask the underlying nutritional deficiency responsible for the lack of a natural cycle. So yes, it matters very much! More on this here.

Bottom line: Absent periods are a major red flag for females and should never, ever be ignored (OR masked by an inappropriate, artificial contraceptive). Importantly, it's not just a missing period that can cause problems and obviously don't show up in men. Any form of hormonal dysfunction could have disastrous long-term consequences for an athlete's health and performance. Addressing these issues are extremely important – regardless of whether you want to have children someday.

Fortunately, most of the mental and physical health consequences of RED-S are reversible. What's more, taking steps to restore an energy balance should result improved health and performance longevity. For advice on where to go for help, head here.