Let’s rewind to this time last year: I was running every day at 5am, often clocking 20 miles before breakfast with maybe a gel in my pocket if I was going really long. I was flying along. I felt on top of the world. I’d read all the articles about fasted training (running in a glycogen depleted state) and the benefits for some incredible endurance athletes. Point of information: the thought behind fasted running is that it reduces the body’s stored carbohydrates to help train the body to burn more fat (which we have a comparatively unlimited store of versus more rapidly depleted stores of glycogen in the liver and muscles) during endurance events. Essentially, it teaches the body to adapt to low carbohydrate availability with the aim of improving endurance capacity and our ability to go further. You might have also heard people talk about ‘training low’ or being ‘fat adapted’.
In my case, the miles racked up: my diet stayed the same. How far could I go?
It turns out pretty far. Until I couldn’t. It started with the tendons niggling, then tendons really niggling, then tendons really hurting. My performance plateaued. I wasn’t getting faster or stronger and morning runs were a thing of the past: I could no longer muster the enthusiasm. However, the real wake up call came when my periods waned to a trickle and then stopped completely, around the same time that I got a call from the doctor after a routine blood test. I was severely hypoglycaemic and, by the lab analysis, should really have been in a coma at the point of testing. My Vitamin D levels were also low.
Are you alive? (Yes, and using a phone too!)
Did I run? (A bit…)
Did I eat before and after a run? (A bit…)
Had I ever heard of RED-s? (No; should I?)
By the end of our conversation, I had not only heard of RED-s but had had my mind blown by the ‘revelation’: fasted running may have some benefits for male athletes (and even then in moderation) but for female athletes, it could not only lead to the plateau in performance that I had experienced, but light a veritable forest fire of hormonal chaos. Oh.
Now I am not advocating that everyone should immediately change their diets and I am not a doctor or scientist. Indeed, the key take away, from my own experience (and I emphasise ‘my own’) is that everyone’s physiology is unique: what works for one person may not work for another. However, there is more and more evidence that everyone should be thinking about how they fuel the work done in their training, and especially women.
Herein lies the irony. I had based my pseudo-scientific fasted running on studies conducted on men. I had read articles from a male perspective of what worked for them. I hadn’t heard of Relative Energy Deficiency or the impact of fasted training on women’s physiology. This despite the fact that female road-race participants have exploded over the past few years: an increase that is mirrored in trail running, albeit at a slower rate. Indeed, at ultra-endurance events, women are topping podiums and outcompeting men at events like 24hr races, the big 200 mile races in the States and Backyard Ultras.
The reality is that there is a gender-gap in performance research, which individuals such as Megan Roche (professional trail runner/coach and epidemiology PhD candidate) and Dr Emily Kraus (sports-medicine physician and clinical assistant professor at Stanford) are working to address with the Stanford FASTR (Female Athlete Science and Translational Research) Program, which aims to empower female athletes from a range of backgrounds and abilities to achieve longevity in sport.
It stands to reason that, when the studies out there are based on male subjects, it can result in uninformed guidance on how women should train and fuel which can, in turn, lead to conditions characterised by under-fuelling: RED-S (relative energy deficiency in sport), poor bone health, and even depression and anxiety. That’s not even to touch on the potential for a disordered eating and ‘ideal body’ narrative to become the norm. If running is meant to be enjoyable, releasing, mindful, empowering, well, none of the above appear to tick any of those boxes.
You can read for yourself the myriad of studies on how fasted running, in moderation, can lead to improved fat oxidisation. However, whatever the potential metabolic gains, alternatively, training with limited carbohydrate stores may ultimately impair intensity and duration. In other words, unless you are working for a short time at an easy intensity, you are unlikely to see performance gains. If, like me, you were doing both high intensity and duration (also a red flag I might add), you may experience fatigue, increased perception of effort, and compromised speed.
If you read Dr Stacy Sims’s book ‘Roar’, you can follow the logic of how this is all relevant to female athletes in particular. She explains how, when training in an energy-depleted state, concentrations of cortisol (a stress hormone) go up. If women train consistently in a fasted state, then those high levels may become chronic and lead to hormone imbalances. The knock on effects don’t make for inspiring reading: amenorrhea (lack of periods) and interference with fertility, bone stress injuries, long-term reduced metabolic rate, diminished athletic performance, and slowed recovery time. What may work for male athletes in moderation, does not necessarily work for women.
This does not equate to never doing fasted runs or re-inventing the wheel in terms of your day-to-day diet but, rather, it’s about tuning into your body and recognising what nutrition is going to boost your performance, overall health and long-term goals. Knowing what I do now with my own health journey, I am aware that both my mind and body respond well to always eating enough in both training and life. Indeed, when I’m training hard or racing long distances, I find that my body actually likes over-fuelling: something which I’ve certainly had to work hard to wrap my head around. For someone who has literally been on a long road with disordered eating, this has been one of my biggest challenges. One thing I do know, however, is that getting into endurance running and, having learned from those initial ‘fasted’ months and health scares, re-framing food as the fuel that enables me to do incredible things, is probably THE factor that keeps my recovery on the straight and narrow and doing the thing that I love most: running. I’m not the only one. Mimi Anderson writes candidly in ‘Beyond Impossible’ about how running and the need to fuel her running helped her recovery from anorexia. She is just one amongst many female runners that have bravely shared their stories.
My struggles with fuelling have been further compounded by chronic auto-immune issues. I try, where possible, to choose anti-inflammatory fuelling options that will still give me the energy I need to sustain many hours on my feet. I have long incorporated honey into my diet and finding the Hilltop energy gels was a way to extend its benefits into my training in a convenient fashion. My body prefers foods with short ingredients lists and Hilltop’s are about as pure as they come. Having experimented with so many fancy, unpronounceable concoctions over the years, going back to basics has in fact been the answer.
The bottom line is that restriction of food is generally never going to be a mentally healthy mind-set for anyone but all the more so for young people in our media-driven world where they are exposed to the, unhealthy at best and profoundly dangerous at worst, dialogues around body image at an earlier an earlier age. As a PSHEE educator, I want the young people that I work with to be more informed about their bodies and celebrate what they can do when they are energised and healthy – no matter what their goals, their shape, their size, their gender, their race, their sexual orientation or their financial status (and there’s a whole other conversation about the gaslighting of underrepresented groups in eating disorder discussions and treatment for which I would read Latoya Shauntay Snell’s excellent blog for a far more informed and comprehensive view). I want them to run full of joy and gratitude and to keep running for as long as they still have the will to put one foot in front of the other.
Roar, Dr Stacy Sims
More Fuel You, Renee McGregor
The Happy Runner, David Roche and Megan Roche
Beyond Impossible, Mimi Andersonwww.runningfatchef.com, Latoya Shauntay Snell