Energy availability and RED-S

Why all athletes should care

Relative energy deficiency in sport (RED-S) is a condition that occurs in male and female athletes of all ages. It effects multiple bodily systems and can lead to seriously compromised long term health and performance.

So what exactly is energy availability?

Energy availability is defined as energy intake minus energy expenditure from exercise (above and beyond the energy expended in daily moving about and living) divided by fat free mass in kilogram. Fat free mass is your body weight minus fat mass. For example, a 60kg athlete with 20% fat mass has 60 x 12% = 12kg fat mass. Therefore, his or her fat free mass would be 60 – 12 = 48kg.

(Energy intake – energy expenditure from exercise)/fat free mass(kg) Energy available in kcal/kg fat free mass per day

Energy availability is expressed relative to fat free mass as it reflects the body’s most metabolically active tissues.

Low energy availability (I’m going to refer to it as LEA from now on), is a mismatch between an athlete’s energy intake (diet) and the energy expended in exercise which means that there is too little energy to support the functions required by the body to maintain optimal health and performance.

The threshold for low energy availability varies between athletes, with negative effects occurring from 45kcal/kg fat free mass. The minimum amount of energy availability currently seems to be 30kcal/kg fat free mass.

How does LEA affect performance?

LEA leads to impaired recovery leading to reduced physical, psychological and mental capacity. There is also impairment of optimal muscle mass and function.

LEA can also interfere with training gains by acutely impairing key processes like glycogen storageor protein synthesis, or by preventing consistent and high quality training because of illness or injury.

Even though getting a greater power to weight ratio is commonly regarded as key for performance in sports like running and cycling, doing so by having too low energy available, will actually negatively affect performance and health. Healthy, long-term ways to make weight and reach performance weight is critical, which is why athletes really need to consider adding a dietitian to their team in order to reach their potential.

How does LEA affect an athlete’s health?

• Hormones
  Research shows that athletes with LEA may have disruption of the “hypothalamic–pituitary–gonadal axis”, which is the system that regulates sexual hormones. This is why a female with LEA might lose their menstrual cycle, and males with LEA will have lower levels of testosterone. In addition to this, there is alterations in thyroid function, changes in appetite-regulating hormones (decreased satiety hormones and increased hunger hormones), as well as decreases in insulin and insulin-growth factor 1 (IGF-1) and increased resistance to growth hormone. There is also elevations in cortisol, otherwise known as the “stress hormone”.
  Why do these hormonal changes occur? They occur in order to conserve energy for more vital processes for life – like cardiac function and breathing.
• Bone health
  Low energy availability is associated with low bone mineral density, increased risk for osteoporosis and bone injuries like stress fractures.
• Metabolic function
  LEA decreases your resting metabolic rate, which is the amount of energy you burn at rest. Factors that also affect metabolic function in athletes with LEA is decreases in leptin (the satiety hormone), T3 (thyroid hormone), IGF-1 and an increase in ghrelin (the hunger hormone).
• Haematological function
  The term “haematology” refers to blood. Athletes with LEA tend to also have low levels of iron in their blood. Iron plays a role in transporting oxygen in your body, and low levels can contribute to fatigue and reduced performance. Iron deficiency may also interact with bone health, and plays an important role in thyroid function, fertility and even psychological well-being.
• Cardiovascular function
  Athletes must have the lowest risk for heart disease, right? Unfortunately, low energy availability negatively impacts heart health – due to reduced blood flow, heart arrhythmias, and unfavourable levels of cholesterol in the blood. Early atherosclerosis (heart disease where arteries are narrowed due to plaque accumulation) may be associated with LEA, even in seemingly healthy athletes.
• Gastrointestinal function
  LEA can cause problems with your digestive function due to altered sphincter function, delayed emptying of stomach contents, constipation and increased time that food moves through the digestive tract.
• Immune function
  LEA is associated with compromised immunity, notably infections in the upper respiratory tract and the digestive tract, as well as increased incidences of body aches and head-related symptoms.
• Psychological function
  LEA affects psychological function in many ways, and is associated with increased levels of anxiety, markers of depression and other psychological imbalances.
  Research on male body builders indicate that long periods of LEA (about 20–25 kcal/kg of fat free mass per day, like in the final prep stage of contest diets, might be pathological and have negative psychological effects for males.There is also a loss of strength, hormone dysfunction and mood disturbances occurring in those athletes with body fat of about 4%. That is why it important not to do too many shows and intense preps, and to allow your body enough time to recover and recalibrate after shows.
• Menstrual function
  As mentioned, LEA can lead to a loss of menstrual function, a condition called “amenorrhea”. But how does that actually affect a female athlete in terms of health and performance?
  There are studies that has shown that hypothalamic amenorrhea leads to decreased neuromuscular performance (measured as knee muscular strength and endurance) and reaction time when compared with athletes with normal cycles. One study has looked at the direct impact of amenorrhea in performance by looking at swimmers, and found a 10% decline in speed over a 400 m time trial (after 12 weeks of training) among young elite swimmers with suppressed menstrual function secondary to energy deficiency. In comparison, their teammates who had normal cycles, had an 8% improvement.
  Amenorrhea is associated with low oestrogen, which can lead to sleep problems/insomnia, reduced bone density and increased bone injuries, decreased performance and psychological problems like anxiety.
  Doctors often recommend that athletes that does not get their cycle start using contraceptive pills. However, pharmacological interventions like oral contraception pills are not recommended as first line management in amenorrhoeic athletes. That is because the pills do not solve the main problem – low energy availability – and masks amenorrhoea with withdrawal bleeds. Research shows that oral contraceptives do not support bone health and indeed may exacerbate bone loss by suppressing further IGF-1. Hormone replacement therapy, however, might be more protective against osteoporosis and osteopenia.
• Myths and misconceptions
  A common misconception is that RED-S only occurs in heavily training, elite athletes – however, it can affect anyone who does not have enough energy availability for their daily exercise and lifestyle. Another misconception is that it only occurs in females (with the more obvious indicator of losing their menstrual cycle), however males are affected as well, with one of the biggest health consequences being low testosterone levels.
• Myths and misconceptions
  A common misconception is that RED-S only occurs in heavily training, elite athletes – however, it can affect anyone who does not have enough energy availability for their daily exercise and lifestyle. Another misconception is that it only occurs in females (with the more obvious indicator of losing their menstrual cycle), however males are affected as well, with one of the biggest health consequences being low testosterone levels.

CONCLUSION

Low energy availability can affect your health, performance and quality of life. With so many “experts” on the Internet giving the message that reaching a weight goal is just about “being in a calorie deficit”, or giving generic 1200kcal, 1500kcal or even 1800kcal meal plans, it is important to realise that reaching your nutritional goals is much more complicated than plugging in a number on MyFitnesspal or some macro-calculator found online, and that the consequences of not having enough energy availability is really serious. If this is something you need to address, I strongly recommend seeing a dietitian who can look at you as an athlete and person holistically, and help you to determine how much energy you need to not only survive, but to thrive, ELEVATE to the next level and reach your full potential.

References

Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. 2018. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. British Journal of Sports Medicine. 52:687-697.

Havemann, L., De Lange, Z., Pieterse, K., Wright, HH. 2011. Disordered eating and menstrual patterns in female university netball players. South African Journal of Sport Medicine. 23(3):68-72.

Sherry Robertson and Margo Mountjoy. 2017. A Review of Prevention, Diagnosis, and Treatment of Relative Energy Deficiency in Sport in Artistic (Synchronized) Swimming, International Journal of Sport Nutrition and Exercise Metabolism. 28(4). 10.1123/ijsnem.

da A. Heikura, Arja L.T. Uusitalo, Trent Stellingwerff, Dan Bergland, Antti A. Mero and Louise M. Burke. 2018. Low Energy Availability Is Difficult to Assess but Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes, International Journal of Sport Nutrition and Exercise Metabolism. 28(4):403-411. 10.1123/ijsnem.