Relative Energy Deficiency in Sport (RED-S)
The issues connected with energy deficits in sports were first studied in women under the name of “Female Athlete Triad” in the 1990s. It included three interrelated conditions of low energy availability, menstrual dysfunction, and decreased bone mineral density.
In the last 10 years, the scientific community has recognised that the triad approach was too narrow in scope and that male athletes are also affected – and the broader concept of RED-S was established. Both the Triad and RED-S are consequences of Low Energy Availability (LEA) in athletes, which is typically defined as an intake of less than 30 kcal per 1 kg of fat-free body mass per day. Prevention strategies are aimed at maintaining more than 45 kcal per kg of fat-free mass a day.
Developing LEA and RED-S has serious negative consequences for health and athletic performance as we discussed in the previous articles in this series. Here are some of the most common symptoms of RED-S.
- Fatigue and low energy levels, even after adequate sleep
- Weight loss
- Frequent illnesses, injuries and slow recovery
- Menstrual disturbances, irregular or absence of periods (amenorrhea)
- Low libido
- Decreased bone density
- Cold intolerance, feeling cold more often than usual
- Mood changes, increased irritability, anxiety or depression
- Decreased motivation and concentration, reduced enthusiasm for training
- Sleep disturbances, trouble falling or staying asleep
Female athletes struggle with energy deficits more often
Female athletes are at an increased risk of developing issues associated with an energy deficit. The co-author of a recent study on how low energy availability impacts female exercise performance and immunity, Professor Ylva Hellsten, summarised it like this.
“It is particularly problematic among female endurance athletes. Many athletes focus heavily on weight in their respective sports. Consequently, they tend to go into short-term but intense periods of weight loss with the expectation of performing better.”
Previous research shows a difference among the genders when it comes to collegiate-level sports. Disordered eating is more prevalent among athletes than non-athletes with a prevalence of 1–19% in male and 6–45% in female athletes. Also, clinical testing of elite Australian female athletes revealed that an astonishing 80% of them were showing one or more symptoms of RED-S.
RED-S at the Tour de France Femmes?
A recent study that followed a female pro cyclist at the Tour de France Femmes 2023 showed what being in an energy deficit does over 8 days of elite racing. This cyclist’s average daily energy intake was around 5,200 kcal while her expenditure was around 7,600 kcal. On average, she was in a 2,400 kcal deficit every day which resulted in her losing 2,2 kg of body weight by the time the Tour was over. Her performance remained at a very high level throughout the race but her health suffered. She experienced three typical RED-S symptoms including weight loss, oligomenorrhea (infrequent periods) and low thyroid hormone T3. You can read more about the research and her diet at the Tour in our previous article.
Why are women more vulnerable than men?
There are several reasons why women are more prone to disordered eating and suffer from symptoms of RED-S more often than men. For one, female athletes are subjected to more societal pressures, body image concerns, and sport-specific demands when it comes to body composition. However, according to the research literature, women also seem to tolerate insufficient energy worse than men.
Low energy availability can cause a woman’s oestrogenic levels to drop drastically. Since oestrogen protects the circulatory system, muscles and bones, this has extensive effects on a woman’s physiology. The harmful effects of not eating enough for long periods of time, especially in women, can therefore also be lifelong.
“Based upon the rather limited research in this area, it seems that men are able to tolerate reduced energy intake before it affects us negatively. This indicates that women in particular are a vulnerable population in this respect,” said the lead author of the study, Jan Sommer Jeppesen.
What can we do about it?
The first step is spreading awareness about this issue. The dangers of RED-S need to be common knowledge, especially among young female athletes. The second step is to act quickly if you or someone you know is experiencing any of the common symptoms of RED-S and fix the energy intake. Finally, we need big sports organisations, national teams, and coaches to take this seriously and set their athletes on a healthy path that’s sustainable over the long term.
