Is it overtraining or is it underfueling?

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As I write this, we are in the build up for the fall marathon season. For the early October races, we are into about 6 weeks. More advanced runners are cranking into workouts while beginners are just starting more intensity. Regardless of the level of the runner, it is far too early to be complaining of the dreaded “cumulative fatigue.” Yet, so often I will see people saying that they are just completely out of it and not sure if they are going to make it. That is a tough spot to be with that long left to go. Like anything in life, it’s usually not just one thing that is causing the issue, but a combination of things. However, if we do fix one thing, a lot of times it leads to improvements in other areas. In this case, the usual culprits are training too hard, not adjusting for the heat, and underfueling. Over the years, we have addressed training too hard and not adjusting for the heat early on enough. I’ll list some references to key blogs below on those topics. For now, lets focus on underfueling and the consequences of not fueling for work. 

Individualizing heat and humidity calculations

Heat Acclimatization 

It is easy to overlook underfueling because a lot of times, the symptoms are the same as overtraining. The conundrum is that a person rarely wants to take time off, so they push through and ultimately it becomes a self-fulfilling prophecy. They were underfueled, masked as overtraining, but never fixed the underfueling so their body eventually just broke down. Given that, what are we looking at with symptoms of underfuleing? 


While there are many more you can add to the list, I included what is most common with the athletes I work with. These seem to be the most common. 

  • Lack of energy. This is definitely the most common, but also the most likely to get confused with overtraining. If you are just dragging and you are only a few weeks into your training or even 2 months, then there is a good chance that being underfueled may be playing a part. 
  • Insatiable hunger OR No appetite. Many times, you’ll see people who are training for a marathon for the first time and they are eating everything in sight and at any point during the day. To me, these are usually newer runners who have never been in this position and don’t necessarily quite get how hard they are working. People who chronically eat less than what they really should be at seem to be able to suppress the feeling of hunger. 
  • Nagging injuries (slow to heal injuries too). I’ll see this a lot. As soon as we ramp up training, things go great for a few weeks, then it’s a gradual spiral to downtime from injury. The athlete seems to develop something regardless of the type of training, how slow they build up, or how long they have done recovery exercises. The first thing I’d look at is the amount and types of calories the person is eating. 
  • Frequent illness. Along the same lines, the athlete might be very susceptible to developing an illness like colds, flu, etc. Whether it’s injury, illness, or both- if they can’t stay healthy we have to look at why. 
  • Gradual loss in performance- As I mentioned people will assume they are in cumulative fatigue way before they really should be. Things will start out fine, or they might just be hard to begin with (depending on what the person is doing), and then just seemingly gets worse. The bottom line is, feeling like crap and getting slower is not cumulative fatigue. That’s either overtraining or underfueling for the most part. I would argue that it’s overtraining brought on in part by underfueling. 

Why it is so important to avoid?

While for the short term, like a few days, having a deficit doesn’t really impact performance. Maybe even a season of lower caloric intake. Unfortunately, you see this with women’s running in particular (at least back in the day). I think now that culture is finally shifting past the “fat don’t fly era.” You used to see it all the time in cross country or with a really good individual. They’d get really thin and have a great season. But, by the time they got back from the winter break, they’d be done. A lot of times they wouldn’t even make it through track season. If they did, it wouldn’t be anywhere near what the xc season was. A lot of times, those times were never replicated. The thing to remember with performance is that you will only perform long term if there is fuel being supplied. If not, you’ll eventually break down. Long term issues can lead to hormone imbalance that leads to tissue breakdown. Performance will decrease. Even if you can stay healthy, I see a lot of athletes spend time chasing times they won’t get because they just don’t eat enough. The usual response to poor performance is that they need to train harder and just set the cycle into even more turbulence. 

How it happens

  • Unintentional underrating. When a person signs up for coaching we offer a nutrition guide for the athlete. I feel like more times than not, a person had no idea that was the amount that they should be eating. Sometimes, it’s not even an issue of adding more “stuff” to their diet, other than actually fueling during workouts and long runs (including pre and post workout). A lot of times, just doing that bumps them up into a much more sustainable range. 
  • Not recognizing actual caloric needs. On the flipside, some people do that consult and they go into complete denial stating that there is no way that they need that much and refuse to admit that they need to eat that much- even though they exhibit a lot of the symptoms we talked about. I will tell you that there is no way you can train for a marathon at 60 miles a week and be under 2000 calories a day. 
  • Trying to lose weight. While it might seem conducive to train for a marathon and lose weight at the same time, it’s not usually a good idea for the performance based runner. Now it might be a byproduct of the training, but it shouldn’t be something that the runner is actively seeking it. At least not during the final 12 weeks. If they are doing a base period and want to change their body composition, then there are some things we can do, but that’s beyond what this post is about. In general, trying to lose any significant weight during the marathon is usually a recipe to just hurt performance and lose the stuff we don’t want to lose. 
  • Fear of carbohydrates. I always get pushback on this, but you need carbohydrates, like you need fat and you need protein. If you are doing something that burns a lot of carbohydrate, you need to replace it. Going back to what I said about unintentional undereating, a lot of times, it’s not even adding a ton more carbohydrates to your diet, but rather fueling your pre-during-after your workouts and that will greatly help with supplying your needs. You just can’t be in the mindset that if I ate all these carbs around my workout, I don’t need any carbs during the rest of the day. No, what I am saying is that if you keep carbs to 40-50% in your diet, keep your diet at that, but also supply the carbs you need for the work you doing. If you do that, your daily diet can stay the same, but overall you’ll consume more carbs (that will either be immediately put to use or replenish what you utilized out of storage). 

What to do if you suspect

At the core of the problem, you don’t have enough calories left over after exercise to fully support physiological function. When you separate the two variables, we are looking at two items, the amount of work we are doing and the number of calories we are taking in. The reality is, we probably have to adjust both of these areas. 

The question becomes, should I track calories? Oh, I loathe it, and I am definitely not a fan of long term caloric tracking. However, to see what is really going on, it might not be a bad idea. With something like MyFitnessPal, you can easily track your activity and your food intake. If there’s something like a 100 caloric difference, you can probably chalk that up differences in accounting. But, if you see consistent drastic differences (especially to the negative) in caloric expenditure versus intake, you probably have some things that need to be addressed. 

One, we probably have to reduce the volume and the intensity that you are running. If you are already injured or sick, this might not require any extra work on your part! For those in training, this might be a blow directly to your soul, but let’s be honest, if you don’t take the time now, you’ll be taking it later and your hand will be forced. Even if you were to take a week off, your fitness loss would be negligible. If you simply reduced the volume and ran easy for a week you won’t lose any fitness AND you’ll start to feel better. I feel like that’s a win-win. 

The second part would be adding more calories to your day. This can be a struggle if you are the type of person who runs so you can eat and then I tell you to back off running. No! At the very least, keep the same volume of food you have been eating. Potentially with the reduction in calories being burned, your body can start to restore balance. If you can find a way, while taking a reduction in training, boost your caloric intake with something nutritious. Fruits, veggies, a quality meal replacement shake (as a snack). Really, this might mean just making sure you are eating three quality meals a day. If you do that, try adding a protein and carb snack before bed. Have small snacks a couple of times during the day. My point is, you might have a lot of calories to make up during the day, but a lot of times that overwhelms the person so we have to just pick something that you think you can do and incorporate that into your day. Small changes over time is usually the best bet. It might not be perfect, but we are just looking for better. 

Ultimately, our goal is to be healthy and able to train consistently. How long it takes for that to happen, well, depends, right? It will depend on how honest you are with yourself, how coachable you are (even if you are your own coach), how severe the problem is, how quickly you can adapt to change, and how long the deficiency has existed. That’s a lot. Odds are, it’s not going to be a couple of days or a few weeks. For women, it may take 6 months for regular menstruation to return and the same for men’s bone density to return. I think the thing you have to consider is if it’s worth it to keep digging a hole you can’t get out of. Is it worth hundreds of thousands of dollars in race fees, gear, and travel to keep being frustrated, let alone putting overall health in jeopardy? Or, do we take the time and fully invest in your health and performance? 

The easiest thing, of course, is to avoid the situation. If you are usually ok, but just don’t seem to ramp up the nutrition with what your training needs, you are in a better position to right the ship much sooner. Take the time to really look at what you need, determine if you are fueling yourself pre, during, and post workout, and make any tweaks you need to. If you can be open and honest with yourself about it, I feel like you can bounce back pretty quickly. 

Two last things for today. One, if you take an honest assessment of where you are at, but are in denial of how serious the consequences can be, I urge you to seek professional guidance. This post was really meant for the people who really just aren’t sure what’s going on. It wasn’t meant to be a cure for any disordered eating. Secondly, overtraining is often some combination of training too fast for the workout, under recovery (easy days too hard, too many workouts to close together poor sleep habits), and under fueling. The vast majority of the people I work with can handle the work scheduled, they just struggle with getting the other facets down. If you can, good things will happen with your running!

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