Athlete with low energy.

Low Energy Availability and the Effects of Undereating for Endurance Athletes

Underfueling is a common nutrition pitfall amongst endurance athletes. Some signs and symptoms include: struggling to get through workouts due to lack of energy, frequently getting sick, feeling constantly hungry, or, in the case of women, experiencing a change or complete loss of your menstrual cycle.

Many athletes struggle to fuel adequately, and to avoid injury due to the nature of endurance and high performance training. However, it is possible to avoid some of these injuries through adequate fueling. 

Endurance sport demands high energy, and it can sometimes be difficult to meet energy needs, especially when the appetite can be suppressed after hard workouts. When an athlete is not consuming enough calories to match the energy they have expended from training and daily life, it can put them in a state of energy deficit. If this occurs for a long period of time, it can develop into Low Energy Availability (LEA).  

What is Low Energy Availability? 

LEA is a state in which the body does not have enough energy to support all of its physiological needs to maintain optimal health. It is a result of an athlete’s caloric intake not being matched with the expenditure from exercise. It may result from altered dietary behaviors, but can also result from unintentional underfueling due to lack of nutrition knowledge. 

Some of the most common reasons for the development of LEA are constant pressure on athletes to have a certain physique, and the belief that you have to be a certain weight to be fast. Intentional or not, LEA can have detrimental health effects on the body, including distributed hormones, mental disorders, thyroid suppression, and altered metabolic responses. 

Impact of LEA on Training, Recovery, and Health

LEA can severely impact training and recovery, but more importantly it can impact your overall health. Some of the negative effects of undereating and LEA include: 

  • Fatigue
  • Suppressed immune system 
  • Irritability 
  • Depression and anxiety 
  • Gastrointestinal problems (constipation and bloating) 
  • Reproductive issues (irregular or absent menstrual cycle) 
  • Decreased bone mineral density 
  • Bone injuries (stress reactions/fractures) 
  • Decreased muscle strength 
  • Inability to recover between training sessions 
  • Lack of improvement in performance despite hard training 

Because endurance athletes are used to training long hours and feeling discomfort, it can sometimes be difficult to recognize these symptoms. Building awareness and learning to listen to your body is important, knowing when to keep pushing and when to take it easy. Taking time to recover from hard sessions, reducing effort on easy days, and taking rest days when needed, are just as important as the hard training when aiming to improve performance. 

Many athletes think they need to restrict their energy intake on days they are not training as much. In reality, they should be consuming the same amount, if not more, on those days, to provide the body the energy it needs to recover and get ready for the next hard training session. 

Ways to Overcome LEA: 

Some general tips for overcoming underfueling include the the items below, but to understand individual needs it is important to consult a Registered Dietitian: 

  • Set performance goals rather than goals based on weight or body image.
  • Keep a training log to identify trends in performance, energy levels, and overall feeling and well-being.
  • Work with a coach, sports psychologist, and Registered Dietitian to keep your performance and nutrition on track.
  • Eat before workouts. 
  • Fuel during workouts if they exceed 60-75 minutes. 
  • Refuel 30-60 minutes after workouts with a balanced meal or snack containing carbohydrates and protein.
  • Don’t avoid carbohydrates, as these are an essential fuel source, and should be included in most meals and snacks for optimal fueling and recovery.
  • Aim to eat a meal or snack every 2-3 hours.

What About Relative Energy Deficiency in Sport (RED-S)

Relative Energy Deficiency in Sport (RED-S) is a broader concept that encompasses LEA and  is characterized by low energy availability (with or without disordered eating), amenorrhea (lack of menstrual cycle; in females), and low bone mineral density.  It affects both males and females and leads to impaired performance, increased risk of injury, and long term health consequences. It often takes years to diagnose and can take many years for recovery.

Final Thoughts

In conclusion, it is important to be conscious of fueling, and making sure you are eating enough to support the high demands of endurance training on the body. If you are struggling with underfueling or disordered eating thoughts, reach out to a coach, dietitian, or trusted friend/family member to get support. 

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