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Relative Energy Deficiency in Sport: Are we Cycling our Way to Illness?

Adam Upshaw

Adam Upshaw

It is important to become mindful of our energy needs and avoid the severe consequences of RED-S in Cyclists and other sport-related energy deficiencies.

Is it actually possible for exercise to lead to poor health outcomes?

There are certainly situations where too much exercise may potentially have detrimental physiological effects.  One of the most common circumstances, especially amongst athletes who participate in weight sensitive endurance sports, and which has received much attention of late in the virtual cycling world, is a condition called…

Relative Energy Deficiency in Sport (RED-S in Cyclists), or REDs for short.

What is RED-S in Cyclists?

In many weight-sensitive sports there is an emphasis upon low body weight, and therefore a restricted caloric intake is very common.  This often leads to a pattern of low energy availability, which is described as not having enough dietary energy to match energy expended during exercise.


If this is maintained for a significant period of time and becomes chronic, athletes will begin to experience progressively worsening symptoms, such as:

The umbrella term given to these conditions when the direct result of low energy availability is termed RED-S in cyclists.

Does this mean we should stop doing our 4h weekend rides?

Certainly not, but there are steps we must take to ensure our cycling addiction is a healthy one that doesn’t become a detriment to our physical and psychological self.

Steps We Can Take to Determine if We Are at Risk for RED-S in Cyclists

Perhaps most obvious (but not always easy), cyclists must ensure they are getting enough calories to accommodate their energy expenditure needs.  This can be done by tracking daily intake over a period of 2-3 weeks and comparing that with average total energy output.

Total Energy Output = Resting Metabolic Rate (many online calculators available) + Energy Expenditure from Exercise and all other Activities 

If you find your energy intake is chronically lower than energy output, it might be time to take in a few more calories throughout the day.

person standing on scale with bare feet

You can also perform a relatively easy calculation to assess whether you have a sufficient dietary intake for ONLY the exercise energy expended.


Although it may seem simple, the ability to accurately predict caloric needs using this formula has been brought into question. Nevertheless, it can provide a close approximation.

Energy Availability = Energy Intake – Energy Expenditure from Exercise,
divided by your Fat Free Mass (ffm) in KG.

Fat free mass may be a difficult number to obtain for most, but a rough estimate based upon your body fat percentage (provided by a smart scale) will suffice.

Fat Mass = Body Weight x Body Fat Percentage/100
Fat Free Mass = Weight – Fat Mass

Once calculated you should hopefully see a number between

If lower, you are at risk of not meeting your caloric needs for the exercise completed.

scale with a tape measure

The Simple Step We Can Take to Avoid RED-S in Cyclists

If you were told there would be no math in this class and would prefer to leave it back in the 9th grade, you can always…just simply be a mindful eater. 


Of course, this may be easier said than done, especially when your judgement is clouded by a drive to excel and achieve outstanding race results.  By not letting yourself become hungry during training or racing, or not denying the urge to eat when off the bike, you are putting yourself in a position to avoid energy deficiency.  


If you have symptoms of low blood sugar (hypoglycemia), like cold sweats, tunnel vision, and an empty pit in your stomach, which becomes frequent in between meals, things have gone too far and you will need to be more conscious of your nutritional needs.


Unfortunately, this method can be compromised by following a strategy (albeit unintentionally) of consuming satiating non-nutrient items, like black coffee and liters of water. Further, having smaller infrequent meals vs. the more traditional 3-4 larger meals per day can impair hunger cues and total daily caloric intake.


Nonetheless, by developing the ability to be fully in-tune with your metabolism, and motivated to positively act on those cues and avoid unhealthy strategies, mindful eating can be a useful strategy to develop.

Conclusion-RED-S in Cyclists

Dropping weight to pedal up a virtual mountain faster isn’t worth the negative health consequences associated with chronic dietary restriction. It is important to keep your diet and energy needs in proper perspective.  Be honest with yourself, what you are feeling, and the reasons why you have chosen to be a cyclist and compete.  

You cannot out cycle a poor diet, but you can cycle your way to poor health!

It should be noted that REDs is not something that should be self-diagnosed or that you must deal with on your own.  Rather, if you experience any of the signs and symptoms noted above, or even just have negative emotions associated with eating and food, you should seek support and contact a health professional for consultation.   The National Eating Disorders Association

For more expert nutrition insight and information from exercise metabolism professor Upshaw, check out the Nutrition page of The ZOM!

Your Thoughts?

Do you have any tips for making mindful nutrition choices? Comment below! Your fellow virtual cyclists want to know.

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[…] and Nutrition and the severe consequences of sport-related energy deficiency—RED-S. Yet we continue to make the same mistakes we have when outdoors despite many physical barriers […]


[…] Read: Relative Energy Deficiency in Sport: Are we Cycling our Way to Illness? and A Recent Study Shows Virtual Cyclists Don’t Meet Their Nutritional […]

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