Are you underfueling? Even if you have weight loss goals, you’ll want to make sure you’re giving your body the fuel it needs to give you energy and strength, especially as a runner. 

In today’s episode, I am talking about what underfueling is and how to recognize the symptoms of an underfueled body. I’ll go over how to fix underfueling and avoid RED-S (Relative Energy Deficiency in Sport). 

What’s in this episode:

  • What underfueling is 
  • How to prevent underfueling and scenarios when underfueling occurs
  • Symptoms of underfueling
  • RED-S and how it affects athletes 
  • How to fix and prevent future underfueling

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Transcript for Episode 4 of Fueled for More

Hey runners, welcome to your Fueled for More a podcast where we help new and experienced runners alike improve their nutrition and feel their bodies. I’m Starla, a dietitian, Olympic Trials marathoner and body and cultural diversity advocate. I believe in showing up for your run, for your life and for yourself at full capacity. And when you feel your body well, you set yourself up for success in your sport and beyond. Ready to run? Let’s go. 

Hola runners. Welcome back to the Fueled for More podcast. I am so excited to dive into today’s episode on Underfueling, and I know last week we talked a lot about your goals and your whys and all of that good stuff. So this episode, I want to go into a little bit more around the refueling aspect of performance. And if you are having some goals around weight loss and so forth, I hope that this whole episode provides some insight as to sometimes why we do want to make sure that if your goal is weight loss, that you are working with a medical practitioner or dietitian to help you in that goal as well and with underfueling. What are some of the key things that we want to be aware of as you move through your training cycle and maybe even have to readjust your goals for a time period So that way you can actually perform at the highest level that you’re trying to get to. I know training for a marathon can be a really challenging goal for a runner. We all want to have the perfect training cycle and feel like we have done everything possible to have a PR performance day. And as a culture obsessed with PRs, thinness, and our GPS watch data, runners can often find themselves following a prescription of what, how much and when to eat. That may not be health-promoting for you guys. So when a runner falls into this diet culture track, they can often find themselves in a vicious cycle of under-fueling and overtraining, and then we just don’t feel good at all. So I want to help you guys prevent that. 

Many runners also don’t know what Underfueling is, so underfueling it means not eating enough or not eating enough of the foods that will prioritize your recovery and energy performance. So those nutrient dense foods that we want to get into our diet as well. This can undo the hard work you have put into your training, and when that happens, it can really start to have a negative impact on your life outside of sport as well. So kind of rolling over into your everyday lives. It can impact family, our relationships, how we think and thrive at work as well. So all of those things become impacted by under-fueling. And I want to dove into what kind of scenarios I typically see where a runner is under a feeling. So that way we can prevent that from happening. So some of the scenarios that I typically see are skipping fuel during a long run or workout skipping or avoiding or even forgetting to eat when you have a double workout day or maybe have a really busy schedule and you work through lunch and then you get to dinner time. This can be intentional or unintentional as well. So I know after runs and workouts, many people don’t feel hungry, and so they move on and try to eat enough throughout the day. And sometimes it just may not be enough. So I know this can be unintentional or unintentional and also not adjusting your nutrition when you increase volume or intensity in a training cycle. So as you move closer to your race day, nutrition will more than likely change, and we’ll have to prioritize different nutrients to get the most out of group training and prevent from injury from occurring. So all of these things can lead to under-fueling. 

I know a lot of people also have a lot of concerns about whether they’re eating enough, and so this is also pretty synonymous with that question of Am I eating enough? Well, if people are doing some of these things, they may not be eating enough throughout the day either. So some of the habits that can cause under a feeling are also going to be typically runners who are avoiding fat. Maybe they’re counting calories or they’re being really strict on their calorie consumption. Maybe they’re also eating very low-calorie diets as well that are not supporting their training and barely supporting their everyday needs. They can also be people who have a low appetite from exercise. So whenever we do exercise, cortisol increases. Our ghrelin hormone, which is our hunger hormone, can also be suppressed. So there’s a real reason why there is, well, is logic. They may also be eating to clean eating enough calories, but not enough nutrient-dense ones. So maybe their diet is full of bars, shakes and so forth, and just not enough of actual food getting on the plate. They can also be skipping a pre-run snack or forgetting your fuel during a run that may also be occurring. So if this happens from time to time, I want to also say that this may not cause a lot of anger fueling. It’s an incidence of under-fueling. But when we’re looking at long term and the impact of under fueling, we want to make sure that we’re aware and not we try not to do that on a consecutive basis or consecutive runs or throughout most of your training cycle, because that can lead to an injury or again, not feeling well for your race day. Some of the symptoms of feeling and it has a really strong connection to our overtraining, is maybe you’re going to have reduced energies, you’re just not feeling good and start losing, losing some muscle mass. 

You have an increased risk of injuries to somebody who’s always injured. That’s a symptom of under-fueling loss of bone mass. So maybe you start to have osteoporosis or osteopenia, maybe a lot of fractures are occurring as well in conjunction with that increased risk of injury. There’s dehydration occurring, decreased strength, delayed recovery. So feeling for all the time just can’t bounce back as quickly from week to week, or maybe longer in the long run. You have increased anxiety or depression as well, so emotional stress is occurring on a daily basis. Decreased concentration and coordination, which can impact workouts and your job or your work or sleep as well, can be occurring. And this one and this one, a lot of people do have a lot of poor sleep hygiene. So many times I try to encourage people to really sustain it with habits or we fix it with habits. And sometimes, if that’s not working, we’re looking at what is a diet and are there any deficiencies occurring as well, which can also be part of under fueling increased risk of disordered eating also occurs and irregular regular menstrual cycle can also occur for female athletes and red ask, which is relative energy deficiency in sport. So I want to go ahead and talk a little bit more about relative energy deficiency in sport. So under fielding and red, as can be seen in female and male athletes. So it’s not just female athletes. Many times we can think of a female athlete who is very thin, but it can be any kind of athlete, really. Most research is on female athletes. However, we’re starting to see more cases of retests and research reflecting where we’re training metabolic and hormonal dysfunction in male athletes as well. Read as is defined by the International Olympic Committee, which is the IOC as impaired physiological functioning caused by relative energy deficiency and includes but is not limited to impairments of metabolic rate, menstrual function, bone health immunity, protein synthesis and cardiovascular health, according to the IOC. 

One of the major factors influencing the development of retests is low energy availability LEA. So if you guys have seen this floating around Instagram the internet low energy availability is a big contributing factor to write us. So we definitely want to make sure that with athletes that we are eating enough. So that way we’re not succumbing to low energy availability. So research has shown that energy availability of about 30 calories per kilogram of lean body mass is the threshold for usual reproductive and bone function in female athletes. And we want to make sure that we are supporting our bones, our menstrual cycles, as well as female athletes. So that way we don’t have a memory or loss of initial function occurring to prevent low energy availability and read as active individuals are encouraged to maintain an optimal amount of forty-five calories per kilogram of lean body mass per day. So I’ve read a bunch of you guys are whipping out your calculator or thinking about calorie consumption, so that is just the baseline. And that does not include when you move through a training cycle, just like I was talking about and you’re having to increase your meat. So the closer you get to race day, we still want to be increasing our needs. 

So we have a nice foundation and then we’re increasing from there. And it may start to sound like a lot, but I bet I bet that you’re going to start to feel so much better if you start to make those changes throughout your training cycle and adjusting your plate and creating a performance plate that is going to reflect your training. So we want to make sure that as she put on more miles and you’re increasing your intensity for a race day, that we are also increasing. And then even when you’re not in a training cycle you’re still supporting your body with enough nutrition. So that way you’re not having these hormonal imbalances occurring and you’re not you’re not under fueling as well. So for all my data-driven runners, if you need more concrete information, here’s some LABS that you may want to review to help you further identify under fueling and track if you are actively trying to improve your nutrition and performance. So some of the ones that I encourage that runners start to look at are vitamin D. You may want to get a full iron panel, which is going to include your ferritin levels. DHEA is also going to be another one, and that’s to help promote healthy hormone development, cortisol and testosterone for my male athletes and for my sorry. We want to make sure that we do include testosterone. So how to fix your under fueling? So how do we fix this and how do we prevent it? So we want to make sure that we understand how much we’re eating first. So we have a strong nutritional foundation that can set us up for future training cycles. What did you? Rest, periods, post-race, recovery, nutrition. 

So having those tools and supplying our bodies with enough nutrition on a daily basis and a lot of times I encourage runners, even if they’re not in the full training cycle, that they’re already laying a nice foundation so that you’re not having to fix everything within that 12 week or 16 week training cycle. You want to maybe start improving your nutrition even before that, so that what your body can handle, all of the stress, all of the mental and emotional stress that you may have to take on as well during the training cycle. And I just always encourage that because I always find that runners are just trying to fix everything at one time, and then they end up getting really overwhelmed and they fall off of their nutrition goals and in the running, it’s just really difficult to do. So I always like to encourage that. You also want to make sure that you get some LABS in as well for suspecting some under killing. You also want to work with a dietitian if you can’t work with me. I always encourage that runners go and seek out a registered dietitian so that way they can help you put together a nutritional plan or even a fueling strategy that is going to help you feel your best. We also want to make sure that we are taking some rest time as well, especially after those training cycles. We want to help our body be able to recover to feel better. So that way we can also prevent overtraining syndrome from happening too. So I always encourage that. 

Other things I would encourage, as well as developing a healthy relationship to your food and being able to identify your value systems within that healthy relationship to food, as well as that is going to help you long term for the betterment of your of your athletic career as well. So that way? Guys, I always encourage the value systems because if a client needs to be tracking their food, it’s going to be more beneficial for a client that needs to track versus maybe I need to pull somebody away from tracking because it’s just making them overly stressed. So identifying what are your non-negotiables in your life is going to be super helpful for you long term. So again, guys, I want to make sure that with under puling before you guys start your next training cycle, that you’re aware of some of the signs and symptoms. If you are feeling warm and your last one, I hope this was a super helpful episode to get you on the right track to give you a good push in a good direction as well. And again, guys, if you need anything, please feel free to reach out and share this podcast episode with a friend. Maybe somebody that you’re concerned about also share that with your training partner, and I hope you subscribe and leave a review on this podcast. And again, guys ideas. I’ll see you guys on the trails and wave hello if you see me. Have a good one. 

Thank you for listening to Fueled for More. Ready to jumpstart your nutrition? Download my free grocery guide for endurance athletes at and be sure to connect with me on Instagram @starla_shines. Adios amigos. See you out on the trails.