Episode 90 – Underfueling & RED-S

Key Topics Covered

What is RED-S? 

  • Stands for relative energy deficiency in sport
    • The Specific Definition is – The impairment of physiological function caused by a deficit in a person’s energy intake relative to the amount required to maintain optimal health, homeostasis, growth and activities of daily living and sport 
  • RED-S used to be known as the female athlete triad
    • TFAT involved energy deficiency secondary to disordered eating and irregular menstrual cycles related to low estrogen which eventually leads to low bone mineral density 
    • However, the term red-s takes in account that this can occur in men, can have a negative impact beyond menstrual and bone health AND does not necessarily have to include disordered eating  

Energy availability 

  • Since RED-S is typically thought to be linked to low EA, it makes sense to define what that is. 
  • There are some flaws we see, but we will start with the simple definition. 
  • Energy availability is measured by measuring calorie intake and calories used in exercise, then whatever is leftover is the amount of calories left for the other functions. If that amount is low, then it is a state of low energy. 
  • For example, if somebody ate 1900kcal and burned 1000kcal in exercise, this would leave 900kcal left for other functions.  
  • While there aren’t specific guidelines, there has been some research attempting put numbers around this using fat-free mass. 
  • Using that research, low EA has been identified in athletes consuming <30kcal/kg of fat free mass per day. Optimal EA is considered >45. 
  • For context for an 80kg athlete with 65kg of fat-free mass, this puts LEA at <1950kcal and optimal at >2925kcal  

Flaws in energy availability  

  • Quickly addressing some obvious flaws in EA before going further 
  • One is that the numbers mentioned in research are based on athletes with really high training loads.
    • For example, there are plenty of 80kg strength athletes who train 4x per week and don’t do much else who would be in a calorie surplus if they aimed for >2900kcal all the time. Their needs would be different to an endurance athlete, for example. 
  • The other main issue with the actual equation is that it ignores that fat stores can be utilised to fuel functions. The whole concept of eating 1900kcal and burning 1000kcal leaving only 900kcal left for other functions is skewed by the fact that your body can tap into your fat stores, meaning you actually have more than 900kcal.
    • SO Leanness is also another variable.  
    • While people with a lot of body fat can experience symptoms of Low EA, it is fair to say that leaner individuals are more likely to experience it 
  • But although there are flaws in the system we can all agree that energy availability plays a role in RED-S. 

How does this RED-S affect health? 

  • Loss of period + fertility concerns 
  • Decreased BMD and long term osteoporosis  
  • Impairments of growth and development 
  • More frequent illnesses and longer duration 
  • Irritability 

How does this RED-S affect performance? 

  • Reduced ability to build muscle 
  • Reduced endurance  
  • Higher risk of stress fractures 
  • Illness effecting training 
  • Reduced concentration and coordination 
  • Increased injury risk 

How to manage RED-S? 

  • Simple options are to either increase calorie intake or reduce training. That’s the simple answer. 
  • Addressing individual situations can be more difficult e.g. if training load has to be high and we are trying to get more calories in, but appetite is limited, then maybe we need to be looking at energy dense foods, for example. 

Specific aspects e.g. BMD (OR do HA stuff) 

  • So in addition to rectifying the energy deficiency, the current research also encourages a high calcium intake and good vitamin D levels specifically for bone health  
  • This is particularly pointed towards athletes who also experience loss of/irregular periods due to low oestrogen levels  
  • Current recommendations include aiming for 1500mg of calcium per day, which is significantly higher than the RDI.  
  • And vitamin D supplementation is recommended at 1500-2000IU per day, if levels are low.  

Can it always be avoided? 

  • RED-S should be avoided if possible. But sometimes it might not be possible in rare cases. 
  • One example of this be certain phases of endurance training. Some athletes at an elite level may or may need to dip into a state of LEA to get as lean as they need for optimal performance.  
  • Another example is bodybuilding. The vast majority of women who compete in bodybuilding get HA and likely would be defined as having RED-S. If we tried to avoid that in all cases, would people get stage lean? 
  • In some cases, it can be about risk mitigation and trying to do things as well as possible, within the constraints of a sport. If somebody needs to get into this state for an event, it often makes sense to get out of it as soon as realistically possible.  

As an athlete, RED-S is a great thing to be aware of and if you feel you are displaying some of the symptoms of low energy availability, it is best to seek out help sooner rather than later. 

Relevant Links/Resources

Related Blog Posts