If you read running websites or magazines, view social media accounts of various athletes, and perhaps overhear conversations in your run community, in the past few years you may have noticed an increased attention to a topic called RED-S (pronounced reds), or relative energy deficiency in sport, which can also be called low energy availability.
Low energy availability is most accurately calculated by removing the energy cost of your daily exercise from your total dietary caloric (energy) intake, and then having what is left not being enough energy (calories) to support the body’s normal physiological function, such as bone metabolism, endocrine/hormones, reproductive system, etc. Low energy availability is associated with downregulation and impairment of key physiological processes due to the lack of adequate energy support.
That’s the scientific definition. I simply call it “Not eating enough for your activity level.” Even simpler, that translates to not eating enough.
Not Eating Enough
For a couple decades, one piece of the larger puzzle of relative energy deficiency was known in the sporting community. That piece is the Female Athlete Triad, in which female athletes present with a pattern of low energy availability with or without an eating disorder, in relationship with amenorrhea (lack of menstrual cycle), or irregular menstrual cycle, and low bone density leading to osteopenia and osteoporosis. What we now know is that the Female Athlete Triad is just one section of a larger picture of pathophysiology that can present in athletes with long-term low energy availability. And it is not just a female athlete concern.
When active individuals are not eating enough for their on-the-move lifestyles – the body, because it is wise, makes decisions about where it is going to prioritize its precious calories. So if you’re going to go for a long run in the forest for several hours, followed by an evening hike or weight session, and then follow with something similar tomorrow and the next day, and throw in a weekend of back-to-back long runs, AND you’re routinely not eating enough to meet your caloric needs, the body is going to choose where to spend those nutrients—because when this precious energy is used for one function, it is not available for another one.
Essentially, you are putting your system into survival mode.
And it plays out along these lines as your body says, “Well, if you’re going to make me go do these workouts, I’ll put my energy here, though maybe with a little less pep, energy, and high-intensity ability, but I’ve got to compromise somewhere, so I’ll make a trade-off over here with bone metabolism, or over here with female reproductive hormones or thyroid health, or immune function, or over here with the GI system and the ability to break down nutrients in food (because digestive enzymes are made of proteins which may be lacking in the diet), or muscle and tissue repair or”…. and the list goes on.
On Our Radar
So why is this topic suddenly on more people’s radar? One, we have more research and knowledge on the expanded umbrella of RED-S and the widespread physiological consequences of being at a long-term energy deficit. But also because it’s fairly common for active individuals to not realize they’ve adopted many of the beliefs of the diet industry into their eating habits over the years. Or they may simply be eating to hunger levels, and still not be eating enough.
And, just eating to hunger can sometimes be misleading for us as highly active folks. For instance, many athletes have a suppressed appetite after long or intense workouts or races. In those cases, it’s ideal to replace nutrients after exercise—but when digestion is compromised, the body won’t metabolize the food as it should—hence the potential for working with a nutrition professional to help get the digestive system back to balance. Alternatively, we might need to learn to recognize the symptoms of hunger that often go beyond an empty stomach.
Within-Day Energy Balance
The other side of that low energy availability coin can also mean within-day energy balance. Meaning we don’t stack the majority of our calories into one meal or couple of hours of the day. Eating to fullness, or 80 percent of fullness, is recommended, but if you ever notice you get to the point of overeating after exercise by having excessively large meals that seem to top you up beyond fullness, it is often because of low energy intake throughout the day fueling a need for more food spread throughout the hours. This can often occur after a long run. In this case, you can train your body to tolerate more fuel during a run, and then you’ll likely both recover better, but also will have stressed your body less with the huge energy deficits and then subsequent deposits.
With a more even or adequate energy intake before and during a long workout, you can avoid that ravenous feeling of needing to eat quickly and impulsively.
A Self-Assessment to Help Navigate Your Energy Needs
If this topic has kindled your curiosity about meeting your own energy needs, my suggestion is to start with a self-assessment rather than calculating calories and meticulously tracking meals—those can be highly inaccurate and lead to neurotic food obsession. Ask yourself these questions:
– Am I frequently sick more than a couple times per year?
– Do I struggle with fatigue frequently?
– Have I stopped improving in my performance – either have plateaued or gone backwards despite training?
– Have I had a lot of injuries?
– How’s my overall health? Basic bloodwork results hold a plethora of data on how the body is ‘performing’ internally.
– How is my menstrual cycle and/or sex drive? Women have a little advantage here in that any menstrual symptoms or irregularities* are symptoms telling you to heed warning because there’s a larger health imbalance.
– Do I have a lot of gut upset / discomfort, or food intolerances?
– Am I routinely irritable, depressed, anxious, or have decreased concentration?
– Am I sleeping well?
– and if you have teammates or friends/family that you work out with regularly: Do I eat less than my teammates but have a higher body fat? This is subjective of course because every body is different, but higher body fat and eating less is also a tell-tale sign, since lower metabolic rate occurs with lower energy availability, meaning you might be eating less but weighing more or having more “cushion” than previously.
– and one more because it can become prevalent with long-term low energy availability: Am I thinking about food ALL THE TIME? We know from eating disorder and starvation studies that chronically deprived individuals become obsessed with food, far beyond just being interested in food.
Where to go from here?
Above all, food and exercise should make you feel good. The goal is to be aware and in tune with yourself and your body’s ability to show you signs that something may not feel right or as great as it should.
And you may benefit from professional guidance. If you’re confused or concerned about your needs, or would like a professional opinion, I invite you to reach out to me for more personalized support.
*Women on hormonal birth control will not have the same ability to use their menstrual cycle to gauge abnormalities, since it is designed to eliminate ovulation and the normal hormonal fluctuation that occurs. If symptoms or irregularities occur without birth control, that is a vital sign that your body has an imbalance somewhere.
The information shared in this article does not intend to treat, diagnose, cure, or prevent any disease.
Mini-Meals to Keep You Going
Ideally we spread our meals out throughout the day and leave time in between them for full digestion to occur, so we’re not throwing more food in when the last meal hasn’t fully digested. This causes more problems over time in other ways. In an ideal routine, aim for eating at intervals of four to six hours after a full meal, and two to four hours after a light meal instead of snacking continuously all day. The above article is featured over on the Territory Run Co. run journal, along with three snack recipes for those in-between times, featuring iron and vitamin C-rich Wonder Woman Bars, William’s Oatmeal Raisin Bites, and Sweet Potato Spanish Tortilla. Get the recipes here.
2018 UPDATE: Relative Energy Deficiency in Sport (RED-S)
Fahrenholtz, IL., Sjodin, A., Benardot, D., Tornberg, AB., Skouby, S.,…and Melin, AK. (2018). Within-day energy deficiency and reproductive function in female endurance athletes.
Jeukendrup, A. (2013). The New Carbohydrate Intake Recommendations. Nutritional Coaching Strategy to Modulate Training Efficiency. Nestlé Nutrition Institute Workshop Series,63-71. doi:10.1159/000345820
Jeukendrup, A. E. (2017). Training the Gut for Athletes. Sports Medicine (Auckland, N.z.), 47(Suppl 1), 101–110. http://doi.org/10.1007/s40279-017-0690-6.
McKay, A.K.A., Pyne, D.B., Burke, L.M. and Peeling, P. (2020). Iron Metabolism: Interactions with Energy and Carbohydrate Availability. Nutrients, 12: 3692. https://doi.org/10.3390/nu12123692.
Torstveit, MK., Fahrenholtz, IL., stenqvist, TB., Svlta, O., Melin, A. (2018). Within-day energy deficiency and metabolic perturbation in male endurance athletes.