THE LONG RUN: Advice for all the miles yet to come Part 3


THE LONG RUN: Advice for all the miles yet to come 

By Kirstin Sandreuter 

Happy New Year! I hope 2019 is full of PRs and shattered goals for each of you. Since fueling well will play a key role in getting there, let's go ahead and dive into the final, and arguably most important, installment of this brief nutrition series. 

Nutrition Nugget 3: Trust your body 

Your body is smart. And it probably has some things to tell you if you pay attention.

Signs and symptoms of nutritional deficiencies are everywhere, but you need the right knowledge to recognize them. Especially in your teen years, it is all too easy to under-fuel and over-train without meaning to. Your nutrient requirements are massive at this time of rapid growth, and being active takes your intake needs to a whole new level. If you are catching colds and getting sick frequently, taking longer than usual to recover from workouts (e.g. feeling prolonged or constant muscle soreness), feeling cold all the time, noticing brittle hair and nails, or record an extremely low heart rate (<50 bpm), you may not be eating enough. 

I know that in order to take this to heart, you need to know why it's important for you as a distance runner to meet your intake needs. In short, without enough fuel to run them properly, your body starts shutting down systems one by one, compromising your training and development. This phenomenon and the vast array of symptoms it can cause has become known as Relative Energy Deficiency in Sport, or RED-S. RED-S affects both male and female athletes in several ways, just some of which are detailed in the diagram below: 

I'm going to go ahead and assume you're not hoping to decrease endurance performance, increase injury risk, or become more irritable as the result of your diet. My guess is you hope for the opposite. But unfortunately, much of the common advice you encounter can lead down a path that does more harm than good. The prevailing narrative of "thinner = faster" doesn't help matters. 

To illustrate this, I'll describe one component of RED-S in more detail. One of the most well-researched examples of energy deficiency and its consequences pertains to bone health. In male athletes, there is growing evidence that low energy availability due to underfueling and overtraining can lead to reduced testosterone and consequent impaired skeletal health/low bone mineral density. Having low bone density puts us runners at much greater risk of accruing stress fractures - nasty little cracks in your bones that can sideline you for months at a time. Not fun. 

Similar hormonal suppression occurs in female athletes, which can be summed up in a process called the Female Athlete Triad. This triad describes the interplay between energy deficiency, menstrual disturbances/amenorrhea, and bone loss/osteoporosis. Here's the deal in plain English: girls, you need to be getting your period... period. You may come to find in a few years that many of your active peers aren't getting a period. And you may even have doctors tell you it's okay not to get it, that it's normal for active women to miss periods or lose them all together. That is simply not true. 

Getting a period is your body's way of preparing to deliver a baby, which is something that wouldn't happen without the energy and nutrients to support a new life. If you don't have enough energy available (in the form of body fat stores) to support this, you will not get a period. But why does this matter for us runners? 

When you get a period, the hormone estrogen is released from your fat cells. Estrogen plays a key role in bone growth and development, and is essential to building strong, dense, healthy bones during the short window of time you have to do that. By your mid-20s, your bones will have reached their peak density, and you will no longer have the opportunity to strengthen them. So getting your period now, in order to produce estrogen and build bone, is your most important weapon against stress fractures in the future. Here is a graphic to help you understand how our bodies respond when we don't fuel enough to get a period: 

Trust me, I know this is hard to believe and may sound a bit extreme... especially because remaining at a weight too low to get a period probably will make you faster for a while. Things will go great and you will feel invincible. But as sweet as the results may be in the moment, they won't last. Eventually, you'll reach a point at which your body just can't take it any longer. Your bones will reach their maximum stress load, and begin to break down. That point is a sad one to reach, because even if you start doing everything right from then on, you can't make up for lost time... it will be a long, hard process to build bone density in your late teens and early twenties. I speak from experience on this one, as it describes my own story and that of several teammates' whose college running careers came to a screeching halt way too soon. 

My objective in sharing all this is not to scare you, but to let you know how important it is to eat enough to support your needs, and how to know if you've reached that target or not. Trust your body and the signs it gives you... not a Runner's World nutrition column, comparison to other runners, or the false promises of weight loss to improve performance. 

That said, your two-word take away for this post is: 

Eat Enough. 

I also want to leave you with a few resources for further reading on RED-S and the Female Athlete Triad if this has caught your attention and you'd like to learn more: 

Article on RED-S in male athletes:

Letter to female athletes who have lost their period (by pro runner Tina Muir):

Online educational/support communities pertaining to RED-S: 

And please do feel free to reach out to me too if you have questions on all this. I've included my email in these posts because I wish I'd had someone to discuss this stuff with when I was in high school, and I want you to know you are not alone if you are facing challenges in fueling well for running. 

To fully recap this little nutrition series, here are 3 simple keys to come back to when eating choices start to feel confusing or complicated:

Eat often. Eat variety. Eat enough.  

Now hit the track and put all that quality fuel to good use! The next "Long Run" posts will be focused on confidence-building.  

Until then, as always, run with joy! 


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Kirstin is an athlete turned assistant coach for Greely High School. She studied Nutrition & Dietetics at Cornell University, where she was a member of the varsity track and cross-country teams. You can reach her at