What is Relative Energy Deficiency in Sport?

The syndrome of RED-S refers to impaired physiological functioning caused by relative energy deficiency. The impaired functioning may relate to the metabolic rate, menstrual function, bone health, immunity, protein synthesis and cardiovascular health. The relative energy deficiency means that there is low energy availability compared to the amount needed for all the body functions. It results when the calorie intake from the diet (total calories equals total energy available to use), is insufficient to support the energy expenditure required for health, function and daily living once the energy cost of exercise and sporting activities is taken into account. Put simply, the energy going into the body isn’t enough for the energy being used by the body each day.

The problem is easier to understand if we use an analogy where energy is money. If you are paid a wage of $1000 each week, but you spend $800 on buying new clothes, going out with friends and getting your hair and nails done, then that only leaves you with $200 to pay your rent or mortgage and your water and electricity bills. If all these bills cost $500 per week then you are going into debt by $300 each week. At first, this is ok because you can rely on your credit card to pay for luxuries and leave the bills unpaid, but eventually the electricity company will shut off your electricity supply until you pay them the money owing. So you keep going out with friends and buying new clothes but every week you are getting into more debt and now you can’t turn the lights on when you get home. This is what happens in relative energy deficiency. You keep “spending” your energy on your sport or training, so your body has to shut down normal body functions as you go into energy debt.

Going back to the example about money, there’s only two ways to fix the cash flow problem. You either have to get a pay rise and earn more money to cover your debt (without increasing your spending) or you need to reduce your spending on luxury items (dramatically in the initial stages to recover your debt) until your debts are paid off and then you can start to spend again with a better budget! So if we convert this solution to the energy balance in the body, the only way to fix the problem is to take in a lot more energy (increase your calorie intake substantially) without increasing your energy output (amount of exercise) or reduce your energy “spending” by reducing the energy output from exercise and training until there’s enough energy replaced to get the body systems back up and running normally before you start to exercise again. Sometimes, when the debt is really bad, you need to do both options at the same time.

The most common reason for hesitation from athletes in regards to increasing their calorie intake is that they are worried about putting on weight or “getting fat”. If we go back to our money analogy, that would be like being in debt but worrying about getting rich if your pay went up. There may be some very short term moments when the money gets paid into your bank and you haven’t used it to pay the bills yet, when it appears that you have an excess of money, but the reality is, once you have the money, you will spend it on paying off your debt and your average bank balance won’t change much for a very long time. This is the same as energy balance. If your body is in energy debt, as soon as you increase your energy intake, your body will start to utilize the energy where it is needed. Body systems will return to normal and start to use more energy for their day-to-day activities and the excess energy will be used up. Your body will not store energy as fat in the long term when your body systems are in energy debt but for some people the process to switch back to normal function is a bit slower than others, depending on how long you’ve been in energy debt for, individual differences in body systems and genetics.

What are the potential health effects of RED-S?

We used to call RED-S the female athlete triad because the known complications of insufficient energy intake were cessation of menstrual function and effects on bone health that lead to stress fractures. The term RED-S was created in 2014 as it was recognised that there were far more effects than just menstrual and bone health and that the syndrome could also affect male athletes too.

There are many potential health consequences of RED-S including:

  • Menstrual function (amenorrhoea – loss of menstruation)
  • Bone health (osteopenia or osteoporosis leading to stress fractures)
  • Endocrine effects (changes in hormone systems in the body)
  • Immunological (reduced immunity, more susceptible to infections)
  • Growth and development (effects on protein synthesis and reduction in growth hormone)
  • Haematological (anaemia due to nutrient deficiencies)
  • Cardiovascular (low energy intake causes unfavourable lipid profiles and endothelial dysfunction)
  • Metabolic effects (slowing of metabolic rate)
  • Gastroenterological (carbohydrate deficiency leads to reduction in glucose utilization)
  • Psychological (effects on mood, stress and depression)

What are the potential performance effects of RED-S?

Initially the athlete is able to keep training and there might not be an immediate effect on performance. As time goes on, the reduced energy availability leads to changes in the function of multiple body systems. There is a greater prevalence of viral illness and injuries and a reduced responsiveness to training that eventually leads to performance decrements.

The decrease in performance is multifactorial and is due to:

  • Decreased training response
  • Increased injury rate
  • Decreased endurance performance
  • Decreased muscle strength
  • Decreased glycogen stores
  • Decreased coordination
  • Decreased concentration
  • Impaired judgment
  • Irritability
  • Depression

Is the low energy availability always related to disordered eating?

The short answer is no. By definition, there is always relative energy deficiency when taking into account the energy intake from the diet and the energy expenditure by the body on both bodily processes and exercise but this does not mean that the athletes has a psychological problem with their eating. The athlete may eat a healthy, well balanced diet with no features of disordered eating or eating disorders, but the total calorie intake is insufficient to meet the requirements of their body to cover both normal body functions, health, growth and the energy cost of their training and exercise. That being said, there is also a strong relationship between disordered eating, eating disorders and relative energy deficiency and sometimes the athlete needs to be treated for the disordered eating before addressing the rest of the situation.

The only way for an athlete to reverse the effects of relative energy deficiency is to increase their calorie intake. This means increasing the amount of food consumed per day. For some people, all that is needed is education on what types of food to eat, when to eat them and how much to eat per day, but for others it means psychological support and counseling to address their negative feelings and behaviours towards food intake and giving them practical steps to help them overcome their fear of increasing their calorie intake. The answer to the problem is simple but the process of achieving this may be very difficult for some.

Why does it matter if I don’t get my period, isn’t that normal for athletes?

Just because something is common, doesn’t mean it is normal. It is never normal for female athletes to stop having their period. Normal menstrual function (eumenorrhoea) is defined as a regular menstrual cycle occurring at intervals between 21 and 35 days from the age of 15 years old. In adolescents, the normal cycle can be anywhere from 21 to 45 days as the body does take a few years to establish its normal rhythm after menarche (the first period). Amenorrhoea is the absence of the normal menstrual cycle. Primary amenorrhoea is when there has been no menstrual cycle (the adolescent has not had their first period) by the age of 15. Secondary amenorrhoea is when the menstrual cycle starts normally but then at a later date, there is an absence of 3 consecutive menstrual cycles. Oligomenorrhoea is a cycle length of > 45 days and may be a precursor to amenorrhoea in some athletes.

There are many causes of amenorrhoea and it is important to see a medical specialist experienced in the management of the female hormone system (Sport and Exercise Physician, Endocrinologist or Gynaecologist) to investigate the cause of the lack or loss of the menstrual cycle. Functional hypothalamic amenorrhoea (FHA) is a diagnosis of exclusion and is the cause of amenorrhoea related to relative energy deficiency. Marked reduction in energy availability to the body results in changes to the normal hormone systems of the body that are controlled by the hypothalamus (a part of the brain), which subsequently alters the menstrual cycle. Rapid or significant fat mass reduction, even as quickly as 1 month, can compromise menstrual function.

The altered hormonal function signaled by amenorrhoea has effects on both emotional health and bone health. Peak bone mass occurs around 19 years old in women (and 20.5 years in men). Oestrogen increases the uptake of calcium into the blood and it’s deposition into the bone. Progesterone helps oestrogen do its work. Reduction in levels of both these hormones during times of amenorrhoea may produce negative changes in bone structure. Changes in bone structure lead to an increased risk of stress fractures. Athletes with amenorrhoea for more than 6 months should have their bone density measured by DXA scan.

Should I take the oral contraceptive pill to protect my bones from low oestrogen?

If you are taking any form of hormonal contraception there is no test that can be performed to assess your natural hormone levels. The monthly bleeding you experience when taking the inactive tablets on the oral contraceptive pill (OCP) is not a period, it is a withdrawal bleed. These are not the same thing. If you are on the OCP there is no way to tell if you have a normal menstrual cycle, even if you did have a normal cycle before starting it. The OCP is designed for use as a contraceptive, not as a treatment for low energy availability. New research suggests that low energy availability itself also has negative effects on bone health independent of the effects of the low oestrogen that results from it. To fix the problem, you need to address the cause, which is the low energy availability. The OCP is not the answer. It is best to stop taking the OCP if you are suffering from RED-S and use other non hormonal forms of contraception until there is a resumption of a normal menstrual cycle and resolution of RED-S.

Can RED-S affect males?

Yes. This is one of the reasons the name was changed from the female athlete triad in 2014. Although RED-S is more common in females, it can also affect males. The most common male athletes affected are male cyclists who often have severe energy deficiency as well as other endurance athletes such as runners and rowers. Jockeys and athletes in weight class combat sports are also commonly affected but any male can be affected if their energy intake is inadequate for the amount of training they do. Low energy availability alters endocrine function in males too and they may also experience impacts on bone health. Testosterone has anabolic affects on bone including stimulation of the bone building cells (osteoclasts) and increasing calcium absorption and bone formation. Low testosterone levels have been associated with low bone density scores in male athletes with RED-S.

How do I know if I have RED-S?

The diagnosis of RED-S can be challenging, as the symptoms are sometimes subtle. Any athlete who has not had a menstrual period by the age of 15 or who misses 3 menstrual periods in a row should see their medical specialist to be assessed for RED-S. The syndrome can also present as reoccurring bone stress injuries and a high index of suspicion is needed for any athlete who has a bone stress injury, particularly if there is no history of recent increase in volume of training. Other signs that could signal RED-S include sudden, significant weight loss (even if it is intentional), lack of normal growth and development, recurrent injuries and illness, decreased performance and/or mood changes. A thorough assessment by a Sport and Exercise Medicine specialist experienced in the management of RED-S can help with diagnosis and management of the condition. If you are not sure, it is better to get reviewed than to keep quiet, as early detection is critical to prevent further performance impairments and long-term health consequences.

How is RED-S treated?

The treatment of RED-S may involve a team of health professionals including a Sport and Exercise Physician, a sports dietician, an exercise physiologist and a sports psychologist or psychiatrist depending on what is needed by the individual athlete. Treatment centres on correcting the energy deficit by increasing calorie intake and management sometimes also requires a short-term decrease in energy expenditure (reduction or cessation of training and competition) depending on the situation.

Assessment of the effects of low energy availability on all body systems should be perfomed and correction of any abnormalities is needed. Initially the aim is to increase energy intake by 300 – 600kcal / day and to address the energy spread throughout the day and around exercise. Energy balance can be restored within weeks with an appropriate intake of carbohydrate and protein. Weight gain is the strongest predictor of return of menstrual function but this does not have to be fat gain and can be a gain in lean muscle mass. The most important thing to do initially is to restore menstrual function if it is abnormal. This can occur within months but may take longer than a year. Improvements in bone density are slower and may take longer, often over several years. The athletes diet should include 1500mg/day of calcium through dietary sources with supplementation if needed. Comorbid conditions, such as depression, anxiety and other psychological problems also need to be addressed.

If you have any symptoms of Relative Energy Deficiency in Sport or would like to have an athlete health screening to assess your risk of developing the syndrome, a consultation at Shire Sports Medicine can provide an individualised assessment and management plan to ensure optimal health and performance for your sporting career and your life beyond sport.