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Runners - Do you Have RED-S?

Updated: Jul 27, 2020

Maybe it's NOT that you're not training hard enough, eating "clean" enough, or "thin" enough. Maybe, just maybe, it's that you ARE.

RED-S stands for Relative Energy Deficiency in Sport, a syndrome that includes and expands the commonly known condition: the Female Athlete Triad.

As knowledge has grown in this area, we have found that RED-S is not just unique to women - but men as well. RED-S is being used more widely as more research has found this syndrome affects many more aspects of health than menstrual function and bone health. It is currently suspected that women are affected by this condition more than men, but the jury is still out on this. RED-S is currently defined as;

“a mismatch between an athlete’s energy intake (diet) and the energy expended in exercise, leaving inadequate energy to support the functions required by the body to maintain optimal health and performance”.

Essentially, the question is; are you consuming enough to not only fuel your exercise, but do you also have enough energy left over for your body to perform its basic metabolic functions to support life?

This is one of my favorite meals, Homemade Salmon Pesto Pizza. This is store-bought Naan bread, loaded with pesto, salmon, red onion, brussel sprouts, spinach and topped with nutritional yeast.

Limited studies have been performed on men with this condition, but there have been many studies completed on women to provide a general recommendation on how to support optimal physiological function. It has been shown that a woman's optimal energy availability (EA) is usually achieved at a minimum of 45 kcal/kg of fat free mass per day (kcal = calories). Remember, energy availability is the amount of energy your body needs BEFORE exercise has been accounted for. This is the number that allows a woman’s body to support the body's basic functions for life.

For example, let’s take a woman who is 140# and assume 20% body fat. If you have less body fat, then you can expect your needs to be even higher than this.

  • 140 / 2.2 = 63.6 kg

  • 63.6kg - (63.6 kg x 0.2) = 50.9 kg

  • 50.9 kg of free fat mass x 45 kcal = 2,290 kcal per day to support healthy physiological function (OUTSIDE OF ENERGY EXPENDED DURING EXERCISE).

This is a good target, but this number is still going to vary for different athletes. EA is still *relatively* new and there are no reliable measurements of this (yet!). It is a difficult measurement to nail down, but we have enough evidence to say that for most individuals an EA of less than 30 kcal/kg of free fat mass physiological functions are going to be negatively affected. Let’s take the above example to put this into perspective.

  • 50.9 kg of free fat mass x 30 kcal = 1530 kcal (and remember, if you have less than 20% body fat your needs are going to be even higher!)

Now, let’s say you went out for a run and expended ~300 kcal.

  • 1530 + 300 = 1830 kcal.

As you can see, RED-S can occur even without an incredibly restrictive dietary intake. It can occur with or without intentional restriction. In fact, about 1800 kcal is what many apps, programs, and even our culture recommends! While this may work for a more sedentary individual, this is absolutely not enough for endurance athletes!


How do I tell if I may have this condition?:

  • for those assigned women at birth: loss of menstrual cycles, for those assigned men at birth: low testosterone levels.

  • decreased bone mineral density.

  • abnormally low heart rates.

  • decreased immunity.

  • gut distress.

  • fatigue.

How could it be affecting my performance?

  • impaired recovery.

  • impairment of key metabolic processes; like energy storage for your next run.

  • muscle growth.

  • inability to consistently train well and hard.

This is why it is so incredibly important for runners, cyclists, swimmers (and many other athletes) to increase energy intake with increases in training intensity, frequency and duration.

Maybe this is why you’re not performing your best. Maybe it’s not that you’re not trying hard enough, maybe it’s that you’re trying too hard. The good news? This condition can be reversed by intervention by an accredited or appropriately trained expert (like a Sports Dietitian), to enhance nutritional practices, behaviors and beliefs.

Thanks for being here.

Maddi Osburn RDN LD


Do you think this could affecting you? Click here to schedule your free video phone consult with Maddi Osburn RDN LD.


--International Olympic Committee Consensus Statement on Relative Energy Deficiency in Sport (RED-S): 2018 Update:

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