Top 5 Nutrition Mistakes Made By Runners

I recently polled a bunch of my running buddies, asking them what running nutrition themed posts and tips they’d find helpful. Last year I published posts about How to Fuel a Long Run and What to Eat Before and After a Run, so the consensus this time was to touch on some of the typical mistakes that runners often make in terms of their nutrition.

I actually wrote a post on this topic 5 years ago, so I thought it was time to update the post and give it another share!

As a runner myself, I know that a great training plan is only part of your success on race day – nutrition is the other key and it matters, big time. Proper nutrition for exercise will increase energy, prevent dehydration and electrolyte imbalances, correct GI distress, and optimize recovery so you’re performing at your best.

I hope you find this post on the top nutrition mistakes made by runners and how to eat for running helpful!

How to Eat for Running: The Top 5 Nutrition Mistakes Made by Runners -- from registered dietitian Anne Mauney of

Top 5 Nutrition Mistakes Made by Runners

#5 Skipping Breakfast

I often hear from clients that do runs or workouts early in the morning without eating anything first, and then wonder why they lack energy towards the end of their sweat session.

Without any fuel before a run, you’re likely to bonk. Your body needs energy to power through the workout – don’t deprive it!

Aim for fuel that is lower in fat, protein, and fiber (all of which slow digestion), and higher in simple carbs, like toast with a thin layer of nut butter and either sliced banana or some jam.

Heading out the door in seconds? Try something smaller, like a few bites of banana, a date, or even a couple handfuls of a lower fiber cereal.


#4 Overdoing it on fuel the night before a race

It’s important to make sure that your glycogen stores (the storage form of carbs in the body) are full and ready to go on race day, but you can easily do this by making sure to include a carb source at each meal the week before the race.

Flooding your system with large quantities of carbs or anything too greasy or heavy the night before the race will just leave you running to and from the porta-potties.

Aim for something that includes carbs but also has some good protein, and that you eat often/know generally sits well for you.

My favorite pre-race dinner is pasta with some grilled chicken, veggies, and a red sauce, or a simple quinoa or rice and seared salmon.

#3 Not adequately re-fueling after a long run.

Restricting calories can cause bones to weaken and may result in stress fractures, and if you’re under-eating, your muscle is not adequately being repaired and built after long runs!

Be sure to eat something within 30 to 45 minutes of a run, aiming for something rich in carbs and protein.

If you are feeling queasy after a long workout, try liquid nutrition first (like chocolate milk or a smoothie) and then have a real meal later.

healthy smoothie recipes strawberry lemon

#2 Trying something new on race day.

You never want to try a new fueling strategy on race day because you never know how your body will react to it.

Check the race Web site to confirm which drinks and gels (if any) will be offered along the course so you can test them out in advance, or bring something with you that you know your body responds well to.

#1 Not taking in enough calories during the actual run

If you’re running longer than an hour or so, you’ll need to start taking in some carbohydrates while running – generally about 30 to 60 grams of carbs per hour.

Probably the biggest mistake I see running nutrition clients make is either not fueling during their long runs, or not taking in enough fuel.

If you are finishing runs feeling extremely depleted and/or nauseous, fuel may be to blame. The human body has a limited supply of carbohydrates and once this “fuel tank” starts to run low, your performance will suffer.

Exactly how much to take in will be based on your height and weight and will also involve a little trial and error, so practice different types and amounts of fuels during your runs leading up to race day and see what works for you.

For example, during a 20 mile run I might take in one gel and some gummies, 2 to 3 nut butter stuffed salty dates, and a small granola bar (aim for lower fiber, fat, and protein bars in this case – opposite advice from normal life)!

I find for longer runs over the half marathon distance, I tend to need more “real food” fuel vs. just gels and gummies – but that may be different for you!

what to eat during a 20 mile run

If you’re interested in learning more about fueling right for your runs (in a simple, approachable way), check out the Nutrition for Runners Program that I co-authored with a running coach – you can get started for FREE!


  1. 1

    As an elite athlete, I have taken a lot of time to look into this to make sure I have fueled correctly for my training and racing. You have got all the tips right on! The only other one I would say is not just eating salad or high fiber foods either before or just after a run. People think they are being healthy, but it results in an upset stomach and a feeling I wouldn’t wish on anyone! Thanks for the advice :)

    • 2

      Yes, exactly! Fiber is not your friend right before or during a run. :) I always say running nutrition advice is kind of the opposite of normal nutrition advice!

  2. 3

    I’m going to agree with you on all but the last point….you can train your body to run long on no fuel as a way of letting your body learn to tap into fat for fuel. I have done this for two years now and can even make it up to 20 miles this way. You have to keep a low HR to do it, but it’s really a useful training tool for long races.

    • 4

      I’ve heard some about this approach but haven’t talked to anyone directly who has had success with it – have you written any posts about it?

      • 5

        Agree with both of you, great advice… I “fat fuel” as well during training runs; I only use gels during races (or if I am feeling really tired and need some… “mental” help).

        • 6

          Interesting! Why don’t you take the fat fuel approach during races, too?

          • 7

            I don’t know, actually, I think it’s more like a “pshycological” thing… after all, since I train without food, I should be used to run races that way, as well; but it’s also true that during races the pace is different and some “ready to burn” glycogen can be useful ;-) not that I am an expert in anything, though. Just an average runner ;-)

  3. 8

    I kind of think not using some kind of nutrition during a long run would be pretty dangerous. I just asked a friend of mine who is a step below an elite (she’s winning marathons and ultras but isn’t pro) and even she does 3-5 GU during marathons depending on conditions.

    I’ve dumped GU because of the unknown chemicals but I’ve switched to a vegan chia protein bar and pitted dates (sans peanut butter!). The dates work wonders for me. And I’m sticking to water instead of Gatorade/PowerAde too.

  4. 10

    I remember it took me a while to figure out what I could handle before running. I realized FAST that a salad would upset my stomach, and I am much better off eating something solid, like bread and PB. Too much fiber- no no lol

  5. 11

    Great tips. It was great meeting you at the EA event!

  6. 12

    Great tips! I’m just starting to get into longer runs in my training and I’m really enjoying dates as well. But I never thought to stuff/salt them. I’ll have to try that!

  7. 13

    My very first half marathon, I didn’t bring any fuel…I cramped up at about mile 7, so that made the second half of the race quite interesting and VERY painful. Great tips, Anne!

  8. 14

    Once, I did a 20 miler without planning to and only brought along one gel. Terrible mistake.

  9. 15
    Lauren K says

    Cool post and right on! Another misconception is that amenorrhea is “normal” and means you are “training hard and in shape” when in fact it is not at all and can lead to many, many consequences! It is so common with runners, I want to say ~40% off the top of my head. I’ve totally blown people’s minds when I tell them that it isn’t normal at all!

    I also noticed that someone commented about the “train low, compete high” thought of training with low muscle glycogen stores to train the body to better mobilize free fatty acids. I just did a pretty in-depth presentation about that for my sports nutrition class, so let me know if you ever need to know about it!

    • 16

      I would love to learn more about it! Thanks!!

      • 17

        My husband and I are both distance runners and follow the traditional carb focused approach. But I’d love for you to do a follow up post on the glycogen depletion method of training. We have heard positive things about it but are afraid to change up what we have always done. Is there an advantage for more competitive runners?

  10. 20

    Great tips! I like Amanda use the glycogen depletion method, and it has been very successful for me. I have also stopped using Gu and high sugar blocks and gels–you don’t get the burst of energy you do with these products, but I get less cravings, am not as rungry and feel more balanced post run.

  11. 21

    Great post! It’s freezing today in Massachusetts, and I was trying to get up the motivation to head out for my long run. This helped a ton! Have a great weekend!

  12. 22
    Roadrunner says

    These are really good items of advice, Anne, thanks! Very sensible…

  13. 23

    Great post! I am playing with my pre run and during run fueling now so this is timely! I have two questions :) I keep reading about low fat,low protein, low fiber for running but when I am reading label I wonder what is considered low for each? 4g and under? 2nd question – do you use 1 stuffed date to replace what would be one gel?

    • 24

      I’d say yeah, less than 3 or 4g fat/protein/fiber. And yes, the dates replace a gel. One medjool date has around 100 or 125 calories, and is around 25 or 30g carbs, so it’s more or less equivalent to a gel. I only add about 1/2 or so teaspoon peanut butter so it’s not adding a lot of calories – maybe 25 or so.

  14. 25

    i ran a 16 mile training run today and found that i wasn’t that hungry or thirsty. I only took in about 100 calories (1 package of sport beans) and 10 oz of water. I didn’t feel sluggish but my route was completely flat (basically back and forth on the boardwalk for 3 complete loops). It actually got me thinking about race day. I HATE to eat while running and find I get frustrated trying to rip open the packets and eat and wash it down and not feel like there’s a brick in my stomach. But I have it engrained in my head that I must take in 100 calories every 5 miles (500ish calories during a marathon). I’m thinking of cutting back. Going to test this out during my 18 and 20 milers. I’m going to still take in Gatorade at every other water stop to compensate for some additional calories but i think it might free my frustration a bit and not hinder my performance. The stuffed dates look awesome. Yes, curious how many calories/carbs one would be?

    • 26

      One medjool date has around 100 or 125 calories, and is around 25 or 30g carbs, so it’s more or less equivalent to a gel. I only add about 1/2 or so teaspoon peanut butter so it’s not adding a lot of calories – maybe 25 or so. Good luck!

  15. 27

    I am the worst with not eating breakfast before a run in the morning. But I agree, a few bites of banana will usually do the trick :) I am very superstitious on race days though and I always have a peanut butter and banana sandwich! Is anyone doing the Nike Women’s Half in DC in April??

  16. 29

    Love these tips. I can never be reminded of them enough. Thanks Anne for sharing these with us. Wish I could attend some of your speaking events to learn more!

  17. 30

    #1 – Skipping breakfast – seems a no brainer. Except when you’re in a hurry.

    The word “bonk” says it all. The one morning I ran out of the house for an early morning (5 AM) workout before going to work, I barely made it to the last exercise. Never again! Now I keep nut bars in my gym bag in case I forget to eat.

  18. 31

    Okay, so I have to ask about the chocolate milk as I’ve heard this debated so many times! Some people say it’s the perfect recovery drink. Other people say it’s just milk loaded with sugar so you might as well have a milkshake and call that healthy. There must be somewhere to meet in the middle. Is there a particular brand (or brands) that are more naturally-based that you suggest if you’re going to drink chocolate milk? Or DIY with cocoa and maple syrup?

    • 32

      It certainly does have some sugar added, and you wouldn’t want to drink chocolate milk all day long (or after an easy 30 minute elliptical session or anything), but after an endurance workout it’s a GREAT refueling option. I usually buy organic brands!

  19. 33

    I love using dates and have toyed with the idea of adding pb. With my most recent long run I fueled 2 hrs before and saw a big difference.

  20. 34

    I often run in the morning (at least when Mother Nature isn’t being a jerkface) without eating…I’m going to try to eat a little something before heading out the door next time. It’s common sense but I am not very sensible sometimes!

  21. 35

    I think the biggest thing for me is making sure I’m properly hydrated! I ALWAYS know when I haven’t had enough water, can kill any work out!

  22. 36

    Love this post!! So helpful! One of the most important things I think I have learned form racing is to not try anything new on race day…I tried something new during a training run and had a BAD experience. Thank goodness it wasn’t during the actual race!

  23. 37

    I found the last one particularly interesting. I always ONLY do gel during long runs and marathons and started thinking recently that maybe I should actually EAT something. I get an extremely hungry feeling around mile 15 that just gets worse. I’m just not sure what to start experimenting with. Can you provide some examples (besides the dates and granola bars) that you’ve seen runners have luck with??

    Great post – thanks!

  24. 38

    Great tips!! I really need to remember to always eat before a long run and during!! I am beginning to train for a marathon and I know this is important!

  25. 39

    AH! Thank you for sharing these! The biggest mistake I’ve learned through is overfueling the night before. Nothing feels worse then being cramped/bloated one night before the race and waddling to the start line. I’ve never had a good race fueling that way.

  26. 40

    I’ve eaten dates on long runs, but haven’t tried the PB and salt addition. I’ll have to give that a try!

  27. 41

    Yes, awesome tips! I’ve made the mistake of eating too much the night before – now, I prefer eating a bigger meals 2 nights before and simple, small meals the day before. I’m going to share these with the college runners I work on sports nutrition with – thanks!

  28. 42

    Thanks for all this, Anne! I need to try the dates and pb thing for when I’m at work and go for a run after. Question: you mentioned how much carbs you need during a run is dependent on things like weight and height. How do you figure that out?

  29. 43

    Great tips! I think my biggest mistake is not eating after long runs. I tend to shower first and then make lunch, but that can sometimes take an hour or so to get settled and ready to eat. I like the idea of making a smoothie immediately afterward.

  30. 44

    I always make the mistake of not eating soon after a race. I’m usually not hungry, lots of emotions, a little nauseous. So I will not eat until I am hungry. I LOVE the idea of chocolate milk. I have never tried that before…Thanks for these great tips!

  31. 45

    Great post! Simple and to the point with valuable info!

  32. 46

    Nutrition is something that I’m trying to focus on much more this year with all of the races on my agenda and hopefully a full this fall. I’ve never taken fuel during a half marathon, and don’t drink very much water, because I immediately feel it swishing around… But I’m not opposed to it. Just have to find what works!

  33. 47

    Great tips, Anne … ones that I very often give out, as well! I couldn’t agree more with your first comment that running nutrition advice is often opposite of regular nutrition advice … I often laugh at myself for loading up on fiber and reducing added sugars in day-to-day life, and then completely switching that up before long runs/ races :).

  34. 48

    Thanks for this! I’m a half-marathoner who is stubborn and doesn’t like to eat when I’m running, but I know that it’s necessary for 8+ mile runs now — I want to start changing that during my training. Awesome info!

  35. 49

    Great post!

    For shorter runs during the week, I usually have just some orange juice before heading out the door. For long runs, though, I’ll eat a protein bar beforehand and usually 2-3 gels during, depending on the length of the run.

  36. 50

    #5 was (and is) the hardest for me! I try to take gel every 5 miles, but if I’m cruising along, I find myself waiting to take it or waiting for an aid station and then I’m totally thrown off. My BEST races have been when I’ve taken my nutrition seriously and actually stuck with the plan. It alsao took me forever to realize during triathlons that not eating gels (or other things) on the bike is what was killing my run.. not to mention the 70.3 where I thought eating a giant chocolate chip cookie at mile 1 on the run was a good idea?!

  37. 51

    Great tips. I use these methods for running as well as cycling.

  38. 52

    Thanks for this article! I only just started running but these tips are definitely helpful :-)

  39. 53

    Getting ready for my first half marathon. It will take me over three hrs to complete as I run 13-14 min miles. Any suggestions pre race (days before and right before)and during with regards to food and fluids? Thanks.

  40. 54

    Thank you for such a great post! I just don’t know if it is suitable to me or not. I’m on a diet to lose my weight and I’m trying to cut down my calories as much as possible. Is it good for me to eat something before running? Hope to see your answer <3

    • 55

      Yes, definitely eat before (and right after) running! Be careful – it’s not safe to try to cut calories while you are also running a lot/training.

  41. 56

    I have been thinking about running again after years of neglect and these tips were very helpful. I mean, I won’t be doing a 20 mile run anytime soon but i’d like to try something small and I think eating before a run is where I struggle most.
    thank you!

  42. 58
    TrackBuddy says

    Great tips! I totally agree about properly fueling during long runs and races. This marathon training cycle I really got serious about drinking every 2 miles and taking gels (Accel Gel is my favorite) every 5 miles (3.5-4 miles during the actual race), without fail. I did this at my marathon on Sunday and was thrilled that I had no nutrition issues. I passed a lot of people in the last 10 miles too!

  43. 60
    Roadrunner says

    Super advice — and great discussions. My recommendation is to add coffee to pre-run/race prep, although just one cup…

  44. 62

    Love it!!


  1. […] want to know more about fueling when training? Check out my how to eat for running post and how to fuel for a marathon or half marathon. You can also get started with some free […]

  2. […] up, I hosted my final talk of the weekend – my Nutrition for Runners session. I went through the 5 biggest nutrition mistakes runners make and used that as an intro into how to properly fuel before, during, and after endurance workouts. I […]

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