Undereating and Running: Prevalence, Problems, and Prevention

Undereating and Running: The Prevalence, Problems, and Prevention

“There’s no such thing as overtraining, only undereating.”

I forget where I first read or heard this quote, but this succinct advice for endurance athletes significantly impacted how I think about running, both in terms of coaching and my own training.

Granted, I don’t completely agree with this quote: I do believe there is a point of too much training for the human body. It varies from individual to individual, but even then there’s a general point where running more miles will actually cause injure, decrease your athletic performance, and decrease your overall quality of life. Exercise bulimia is a rising disorder in our day and age.

However, that is not the focus of this article; if you want to read about how much running is too much running, check out my post on junk miles.

The focus here is the problem of undereating and running. This undereating can be intentional (disordered eating habits) or unintentional, but as the opening quote indicates, either way, undereating has detrimental effects for the endurance athlete, particularly runners.

Undereating and Running: Prevalence, Problems, and Prevention

Undereating and Running

Undereating poses an unique problem for female athletes in particular, because of the pressure that we and society place upon ourselves. The cover of that fitness magazine told you to eat 1500 calories a day when you were a teenager, and it’s hard to shift beyond that mentality. What about a thigh gap? Shouldn’t you look thin in your race photo for posting it on social media?

Overeating is a significant health concern for the majority of the American population. I will not deny that. However, runners and endurance athletes are significantly different than most of the population; after all, another problem facing a majority of our population is lack of exercise, and that is certainly not a problem if you are exercising upwards of an hour a day.

The Fear of Marathon Weight Gain

Marathon training, more than any event, poses the most risk of overeating and subsequent weight gain. Weight gain is a concern when you use marathon training as an excuse to eat low-nutrition foods all day long. Your body, hungry for the nutrients it needs to repair your muscle and balance your energy, will continue to send you signals to eat. If you continue to choose low-nutrition foods, your appetite will rage and you will pack on the pounds.

There is nothing wrong with enjoying your favorite treats in moderation. However, anyone, no matter how much you run, will gain weight (and face more serious health issues such as high cholesterol and heart disease) if your diet consists solely of bacon cheeseburgers, fries, and whole pans of brownies. Balance is essential, for all aspects of health, including preventing obesity.

However, most experienced runners who train for races regularly do not eat a free-for-all low-nutrition diet.  Most of you reading likely are not that majority of Americans suffering from obesity, diabetes, high blood pressure, and a whole host of other health issues.

Likely, most you are not prone to overeating low-nutrition ultra-processed foods and sitting on the sofa all day. You run more than ten miles a week and eat your vegetables.

In fact, more than likely, many of you are logging 30+ miles per week while being conscientious about what and how much you eat.

If you’re like me, you may even work out twice a day to fit in running, strength training, and other cross training. You log 30, 45, 60 or more miles per week, not to mention CrossFit, yoga, Pilates, hiking, or whatever other activities you enjoy.

Studies such as this one in Sports Medicine indicate that female endurance athletes regularly do not achieve their recommended levels of carbohydrate or caloric consumption. The frequent cause of inadequate carbohydrate intake, which compromises endurance and athletic performance, is “chronic or periodic restriction of total energy intake in order to achieve or maintain low levels of body fat.”

Oftentimes, runners who are overly fatigued from their training, not seeing an improvement in their athletic performance, and not at the weight they want to be aren’t suffering from overtraining as a result of too much running; they are suffering from overtraining as a result of undereating.

Metabolic Hormones and Marathon Weight Gain

What if you still gain weight during marathon and half marathon training, despite monitoring your food intake? Doesn’t that mean you need to cut calories more? No, emphatically no.

If you’re undereating and running, especially higher mileage, you do have to worry about marathon weight gain, but not for the reason of consuming too many calories or too many low-nutrition foods. If you do not eat enough to support your running, your body will hold onto weight and store extra body fat in a phenomenon known as preservation (starvation) mode.

This appears illogical. Shouldn’t calories in equal calories out? Is that not how energy and thermodynamics work?

However, there’s more to the human body than the simple transfer of energy. Hormones play a significant role in hunger and body weight. Metabolic hormones play a significant role in your metabolism, appetite, and body weight – and in your athletic performance.

Let’s break this down without getting too complex or science-y. When you exercise, especially an intense cardiovascular total-body exercise such as running, your body produces ghrelin. Ghrelin is a hormone that makes you hungry; it’s your body’s way of saying, hey, I need calories to support this activity, especially if you want to do it frequently.

Until you eat, ghrelin slows down your metabolism as well. It makes sense: in case you don’t replenish some of the calories burned, it needs to have fat stores as a back up. Simultaneously, the hormone leptin drops, which is what tells your brain that you have enough energy stores and are at a healthy weight. Low leptin levels mean that your body thinks you need to gain weight.

(This article from Outside provides an excellent summary of how these metabolic hormones function for endurance athletes.)

By eating before, sometimes during, and after exercise, and by eating enough, you keep your metabolic hormones in check. When you don’t eat enough, the hormones stay unbalanced and your body essentially goes into preservation mode.

Preservation mode (also called starvation mode) slows down your metabolism in response to continual significant caloric deficit. You gain weight, even though you’re barely eating enough to support your activity, so you’re also weakening your bones and increasing your risk of injury. Your metabolism has slowed down.

Some runners avoid eating before, during, and after runs to prevent weight gain. While there can be value to the train low, race high mentality of fueling your runs, even the practice of occasional low carb/fasted runs does not mean you should neglect your pre and post-run nutrition. In fact, if you perform fasted runs (meaning runs over 60 minutes with no fuel before or long runs with no fuel during), it’s all the more important that you eat enough throughout the rest of the day to prevent fatigue, overtraining, or a suppressed immune system.

Avoiding food before, during, and after your runs will also cause your appetite to skyrocket and your body to crave the most quickly available forms of energy (namely, simple sugars). By practicing appropriate fueling for your runs, particularly long runs or hard efforts, you actually are more likely to maintain a healthy weight and improve your athletic performance because you are less likely to fall into a restrict-binge cycle.

That’s not to mention all the problems that can occur from having a low energy balance, such as female athlete triad, stress fractures, and overtraining.

Finally, it should be emphasized that athletic performance and fat loss are contradictory goals. You cannot and should not try to train for a race and lose weight/body fat at the same time. For an in-depth explanation of why, read Heather at FitAspire’s explanation of eating for performance vs. eating for fat loss.

By no means am I an expert on this, nor am I a registered dietician. Speaking from experience, though, I have found that my body weight remains more stable and I run faster and farther when I deliberately ensure I eat enough calories, carbs, healthy fats, protein, and (very important) essential vitamins and minerals to support my running.

Eating Enough for Long Distance Running Means Eating a Balanced Diet: Carbs, Protein, and Fat
Eating Enough for Long Distance Running Means Eating a Balanced Diet: Carbs, Protein, and Fat

Preventing Undereating

As a running coach, I recommend two methods for preventing undereating and fuel your running for optimal health and athletic performance.

Primarily, I recommend intuitive eating. Intuitive eating does not necessarily license you to eat any and all foods, regardless of nutritional value; rather, intuitive eating involves eating an overall nutritional diet while allowing yourself to indulge your cravings in moderation. There’s no counting calories, no “good” foods or “bad” foods, and no crazy mathematical equations. Rather, intuitive eating is adaptable to any sort of dietary preferences (vegetarian, Paleo, etc) or food sensitivities/intolerances while promoting not just healthy eating, but a healthy relationship with food.

Intuitive eating is the Occam’s razor solution of eating: the simplest approach is often the best. There’s no “good” foods or “bad” foods, and no crazy mathematical equations.

However, during intense periods of training, your appetite may not always let you know how much you need to eat. Running can suppress appetite and high mileage runners may struggle to eat enough by just following appetite. I’ve been there – during marathon training my appetite did not always accord with my volume of running, hiking, and strength training, and some days I just found it plain difficult to eat as much as I needed.

While individuals differ in how their metabolism functions, as some thrive on higher fat consumption and others need more carbohydrates, ensuring sufficient calorie intake during high training periods is key to preventing overtraining and staying healthy. Many runners will benefit from methods such as counting calories or carbohydrates, so long as they emphasize diet quality and balance rather than taking a more laissez-faire “if it fits your macros” approach.

Matt Fitzgerald’s The New Rules of Marathon and Half Marathon Nutrition is my favorite source for how to make sure you are eating to support your training.  This book emphasizes consuming enough carbohydrates for long distance running in addition to eating high quality foods, but still allows (and even encourages) moderate consumption of treats such as sweets, fried foods, and alcoholic beverages. It’s still an intuitive approach, just one that deliberately prevents undereating during high mileage training.

Like so many things, eating is about achieving balance, both mental and physical. You don’t want to deprive yourself, but you also don’t want to polish off a batch of cookies or every appetizer at the bar after exercise. Aristotle was onto something when he stated that happiness lies in neither extreme, but in the middle. 

Meredith at the Cookie Chrunicles offers some practical tips for how to ditch the scale and make sure you eat enough to fuel your running in her post on achieving balance with your weight. 

Maybe I’m reading into all of this too much, but as a running coach and a blogger, I’d much rather encourage balanced, intuitive, and simple eating than have the weight of encouraging disordered eating upon my conscience. I’m sure I’ve been discussing this topic more than enough lately, but I believe it’s a discussion worth having.

Do you struggle to eat enough during marathon training? 
What’s your favorite indulgence food? 
Do you agree? Disagree? Is undereating a concern for endurance athletes include long distance runners?

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20 Responses

  1. you know I love this! And, I will link to it when I got my post up on the subject next week! it’s so weird when you think about how the reality of this information goes against everything the magazines tell you but since I have lived this when I wasn’t getting my period, I know it’s true first hand. the body is fascinating and will absolutely slow down its metabolism to conserve energy.

    1. Thank you! It is so fascinating and saddening how magazines shape how we think about food and calories and I think it definitely plays a role in how women look at food and running. And then I read that book on half marathon nutrition and it was such a light bulb!

    1. I think it’s something most runners have to learn, whether it’s because of how magazines and body image has influenced our relationship with food or because it’s just hard to learn how to fuel right for long distances. Thank you for referring!

  2. Great info! I know that during marathon training I was eating more, but sometimes I don’t think it was enough. I think part of the problem is that its not always easy to access good food, so while I did my best to pack lots of nutritious meals and snacks for the work day, if I needed something else I didnt really have any options. And I tried to avoid relying on lara bars multiple times a day. I definitely notice that if I don’t eat right after a run that I am hungrier later in the day and don’t recover as well.

    1. Thank you! You bring up an excellent point – access to good food isn’t always easy at work or when traveling. And then it becomes such a dilemma – eat unhealthy snacks or hold off and be hungry. I’ve definitely caved to unhealthy snacks more often than I’d like to admit when traveling and training, but day to day it is a real issue at work.

  3. I have never had a problem keeping up my calorie consumption during higher mileage weeks and in fact, I tend to put on a couple of pounds the more that I run. The only times I ever dip below a healthy weight is when I am extremely stressed out and not running as much. Running gives me an appetite that is impossible to ignore.

    1. That’s really good! Stress definitely pushes weight in one direction or another for everyone – some lose, some gain, but stress always has some impact. A healthy appetite is just another reason to love running 🙂

  4. Well, I think I can safely say I don’t undereat during training, but I do sometimes worry that I don’t eat “healthy” enough. Like a commenter above said, lack of access can be a concern. The catch-22 is that I need to devote more time to meal prep and planning during training, but I can’t because I’m too busy training. I do fine in my running and weight so maybe it’s not as bad as I think it is, but, it could be a lot better. I see a lot of the meals and snacks people post on social media and I feel guilty that my meals aren’t super healthy and “clean”. I have to eat out a lot when we inevitably slack on the grocery shopping, and I do try to make the best possible choices, but I could definitely be better.

    1. You bring up so many important points, Hanna. I think social media is great for somethings, but it brings such awful comparison traps and pressure when it comes to eating. I always say that you never know what else the person is eating outside of the frame of the single (often staged) photo. “Clean” food is such an ambiguous term (really, think about it – does it mean that food doesn’t have dirt on it? I get weird about terminology though like how I don’t refer to food as healthy anymore, just nutritious vs not nutritious). I think an 80/20 rule is a good one – try for 80% of foods from nutritious fruits, vegetables (including starchy ones), whole grains (including some minimally processed foods such as whole grain bread), lean meats/eggs, legumes/nuts/seeds, and diary – but then 20% of whatever you want or is available. Honestly, making the best possible choices is great – life is already so complicated that eating shouldn’t be made any more stressful.

  5. I think this is great information for anyone to read. There are so many warning signs and symptoms that you don’t realize until it’s too late. Great post.

    1. Thank you, Jen! Intuitive eating can be tricky, I think especially if people are coming from disordered eating or very low-nutrition eating habits, but it’s definitely effective in the long run! That’s how people ate for thousands of years.

  6. I love the intuitive eating approach, too! Our bodies are so, so smart if we can tune in and let them guide us. And yes, I am amazed at what an issue under-eating is in the running community. The long term risks are so not worth whatever (small) short terms gains there may be.

    1. It amazes me how smart our bodies are! And they always let us know what we need. I agree, the short term gains of possibly being faster (for a short while) are never worth the long term risks, both the risks in running and the overall health risks.

  7. Thank you for this post. For my age I am a competitive 5K runner and decided to give a half marathon a try. I am following a training plan but I am always tired and gaining weight. I am not hungry and often have to force myself to eat. When I ran in high school and college this was never an issue. Very informative.
    Thank you!

    1. Good luck on your half marathon! Weight gain and fatigue can go hand in hand – usually you’ll find that by eating more nutritious foods (protein, healthy fats, complex carbs), weight stabilizes and there’s so much more energy! Long distance running also requires adaptation – that first training cycle is usually harder on the body, more tiring, and harder on the appetite than later ones.

  8. Yes good Info. I think I need a book on this ! I never get hungry when I run so I cut back. I used to be able to do more miles and lose weight easy. Now my period luteal phase is messed up. I get bad bloating/water retination, gastroal issues,nausea… overall I just feel like hell. Then my period comes and I feel wonderful.Never been lucky enough to lose my period though,lol.

    I am guessing its messed because I dont feel real hunger so sometimes I just eat anyway and shouldnt so I put on weight and I cant run half as much as I used to. I dont know if it’s because I’m hitting my mid 30s now or what.

    Cutting back has helped I think and stress breathing techniques,yoga etc. And sometimes i try the intuitive eating thing. Trial and error I guess !

  9. Thank you for this! I have always been active with sports like rock climbing and yoga, but during quarantine I became hooked on running. Now, nearly a year later, I am running long distances on big, steep, mountainous routes.. it’s so exciting! But I have noticed that I have maintained the same diet that I had when I was doing lower-cardio sports. Which is a very healthy, clean diet, but I haven’t been upping the portions or snacking at all. I’ve even started to feel a slight shift in my hormones (which has led to a concern of amenorrhea) and appetite – I have felt so hungry after some runs that I actually can’t stomach anything and because of this I have started dropping weight like crazy. Upon doing some googling, your article here has been the best source of info I have found! I greatly appreciate your insight and plan on letting more intuitive eating into my day. Thank you so much!!

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