How to Fuel for a Marathon or Half Marathon

Hello my friends! Matt and I are in California right now for the wedding of our friends Heather and Mike, and won’t be back until late tonight, so I’ve asked running coach Jason Fitzgerald of the website Strength Running (and co-author of my Nutrition for Runners program) to share a guest post today on how to fuel for a marathon or half marathon. Given that the Rock ‘n’ Roll DC is coming up this weekend, I figured this timing was perfect! Take it away, Jason!

How to Fuel for a Marathon or Half Marathon
by: Jason Fitzgerald

Jason headshot - Brick - web ready

After nearly a year working together on our Nutrition for Runners program, I was excited when Anne asked me to write about fueling for the marathon and half marathon on her blog.

I love this stuff – and it’s because I learned the hard way. Let me explain…

My first marathon was New York City in 2008. And it was a disaster.

After I passed the 20-mile marker, my race turned into a cliché as I hit the wall, bonking hard and slowing down by more than a minute per mile. Every step felt like a hammer was crushing my quads. At mile 25, a senior citizen passed me.

Poor fueling made me crash early, resulting in excess muscle fatigue and ultimately a 6-month struggle with IT band syndrome.

Sounds fun, right?

Now compare that with my second marathon where I never once hit the wall and my 22nd mile was one of my fastest. I ran 2:39:32, a personal best by over five minutes, and stayed healthy during and after the race.

Jason_Fitzgrald_Racing - Copy

That was the 2011 Philadelphia Marathon and is my crowning achievement of more than 16 years of training.

The difference between the two marathons wasn’t actually my training (both were very similar) but my approach to the fueling aspect of marathon racing.

In fact, I consumed more sugar during the Philadelphia Marathon than what’s in a pint of Ben & Jerry’s ice cream! Sounds gross, but that helped fuel an evenly run marathon.

Today I’m excited to talk about marathon and half marathon fueling so you can avoid my past mistakes and run the best race of your life.

Marathon Fueling 101

Researchers in England surveyed nearly 300 runners at the London Marathon and discovered that only a small fraction ate enough carbohydrate before the race. And those who did eat enough carbs ran 13% faster (this is a HUGE margin!).

In fact, the latest research shows that it’s ideal to consume 7-10 grams of carbohydrate for every kilogram (or 2.2 pounds) of body weight during the two days before the marathon.


If you’re thinking that this is an enormous number of carbohydrates, you’re right. A 150-pound runner would need to eat 477 grams of carbs per day if sticking to the 7g per kg rule. And the English researchers found that only 12% of runners ate this amount, so you’re most likely not fueling enough before the marathon either.

So, what do you do? Follow a few simple strategies to increase your carb intake during the two days before the marathon without stressing yourself out:

  • Include a source of carbohydrate at every meal
  • Snack often (fruit, granola bars, toast, etc. – remember, you’re fueling not eating for health at this point)
  • Have 2-3 glasses of a carb rich beverage like sports drink (we include a great homemade sports drink recipe in the Nutrition for Runners program) or lemonade

This carb-loading cycle might make you feel a little bloated, but that’s normal and it’s only water weight. If your goal is to run your best marathon, it’s necessary to avoid the dreaded bonk and cross the finish line as soon as possible.

During the race itself, it’s beneficial to consume about 45-60g of carbohydrate per hour (or about 2 gels). Combined with proper training and pacing, this should help you avoid “the wall” and run your best marathon.

How to Fuel For a Half Marathon

Thankfully, the half marathon doesn’t require such a strict carb-loading protocol as the marathon. You won’t have to gorge yourself on carbs for days before the race to run to your potential.


Most of us already store enough carbohydrates for about two hours of running at a moderate intensity. So if you’re a sub-2 hour half marathoner, you don’t have to change your fueling strategy at all before the race.

Still, you might give yourself more energy by eating a carb-rich dinner and breakfast right before the race. It’s certainly not a time for avoiding carbohydrates (so don’t eat a salad and a steak…). Breakfast before the race should focus on carbohydrate and be relatively simple: a banana and small bowl of oatmeal is perfect.

During the race, most runners will only need the equivalent of 1-2 gels (or roughly 30 to 60g of carbohydrate) spaced evenly through the race. I prefer one gel at mile 7 of the race, but I’m only running for about 74 minutes. If you’re out on the course for longer than 90 minutes, I recommend two gels.

Remember that gels are optional: find a mid-race fuel choice that agrees with your stomach and tastes good. Most commercial energy bars, gels, bits, and blocks work fine.

And if you want to make your own or prefer more natural, less processed race fuel, we include several make-ahead recipes in Nutrition for Runners.

What questions do you have about fueling for races?

Ask any experienced marathoner if they’ve ever had a bad marathon and they’ll almost always tell you horror stories of races gone awry: bonks, walls hit, and more walk breaks than they’d like to admit.

But isn’t that the beauty of running? The constant search for improvement is what draws us back to long races like the marathon over and over again. It’s seductive. It’s addicting. And it’s what makes our sport so inspiring.


And I’m sure you have plenty of questions about fueling for the half and marathon. So I’m here to help! Leave any questions in the comments on this article and I’ll jump in to answer as many as I can.

If you want to download two audio presentations that Anne and I recorded about fueling and nutrition questions, you can get those right here. There’s a lot of helpful stuff included – including myths about fueling and weight loss – so I hope you enjoy it!

After you sign up, leave your question below and I’ll answer it ASAP!

Jason Fitzgerald is a USA Track & Field certified coach, 2:39 marathoner, and the head coach of Strength Running, one of the largest online coaching sites for runners. His passion is helping runners set monster personal bests.

Related posts from Anne that you might enjoy:


  1. 1

    Very timely indeed! Thanks Jason! I’m running my 10th marathon in April and still am tinkering with what I need to eat before race day AND during. I’ve been taking 1 gel per hour and find myself really tired the last hour (but not hitting the wall). I will experiment with 2 gels during a 20+ mile long run and see how my stomach likes it. :)

  2. 2

    I’m running my first half marathon on Sunday (!) so your post couldn’t have come at a better time. I have been diligent about fueling myself properly the night before long runs and immediately afterwards but during the last 12 weeks of training, I have not had any food in my stomach ahead of early morning long runs. I have liquid electrolytes in the form of Nuun tablets and a cup of coffee and glass of water before heading out but other than that-no food. My training certainly hasn’t suffered as a result and so I didn’t plan on introducing food the morning of the Half. Am I crazy to think I can do this on no solid fuel the morning of the race? Thanks in advance for your reply.

    • 3

      Hey Rosie,

      You could certainly run a half marathon with no solid food beforehand. Especially if you’ve already been doing your long runs this way.

      Then again, it’s not the *best* way to fuel for a half. Since it’s not a good idea to change things on race day (Rule #1 on Race Day is to never try something new!), I think you should stick with what you’ve been doing. If you really want to add some more calories, a cup of sports drink might give you an extra boost.

      Good luck this weekend!
      – Jason.

      • 4

        Thank you Jason-I appreciate the reply. I planned on bringing the Nuun drink with me and sipping each mile since that is what I did during my long training runs. If I ever decide to tackle the longer distances I know that pre-run food will need to be in my future. I love your website and emails. Thanks for the knowledge and inspiration.

  3. 5

    I am training for my third marathon and am still trying to figure out mid-run fueling. I have a super sensitive stomach, so gels are out. I’ve been using Swedish Fish, but am looking for some less chewy options. Or more importantly…how do you eat and run at the same time? I seriously cannot figure this out…I always feel like it never settles!
    Thanks! :)

    • 6

      I love swedish fish! But eating while running is definitely a learned art, something you just have to practice. Any food that’s super portable and you can pop in your mouth makes it easier.

  4. 7

    Thanks for all the info! I have so much nutrition knowledge in my head, but it can get overwhelming based on what my goals are. I have another half coming up in May and this was great timing for me to be able to figure out what and when I should be eating. Thanks!

  5. 8
    Roadrunner says

    Excellent post, Jason, thanks! Wish I’d had this info before I ran my first marathon (and hit the wall just as you did)!

  6. 9

    Two questions:

    1. Is it 7-10 grams of carbs per kilogram of body weight per DAY for two days, or split over two days?

    2. Is Jason single?

  7. 11
    Mary Beth says

    Hi! Thanks for the info. I am training for Boston 2015. I ran it last year and bonked Bad at mile 22. My training went great and I was following my plan to the “T” so I was very depressed when it did not go well. Normally I do not begin taking gels until after mile 10 for a marathon. (In my training, I don’t take them until I exceed 12 miles or more). I know you said take 1-2 gels every hour but in that case, I should be starting them at like mile 7!!! Is that correct? I don’t think my stomach could handle that but I will try some chews instead.
    Also, the hard thing about Boston was that the race starts so late and that makes it even more challenging to eat enough Any advice??!! I want to have a positive experience this year. Thanks!!!

    • 12

      Yes, you have to take about 2 gels per hour (45-60g of carbohydrate per hour). It’s a lot – but necessary to help you avoid hitting the wall.

      A late race starts makes it EASIER to eat more! You can get up early and have a full breakfast with plenty of time to use the bathroom (just be careful, sometimes the lines at the Athlete’s Village are really long).

      Good luck and hopefully I’ll see you there! I’m hosting a meetup at Boston this year.

  8. 13

    Thanks for the informative post! I have run a bunch of half-marathons and find that my need for gels during the race is always earlier (around 6 miles or so) than my when I’m doing long runs during training (around 8 miles or so). Also- love your IT band rehab video! I injured mine last spring and started doing your rehab exercises twice a week. I healed up in a month!

  9. 15

    So happy to see this post! I struggle a lot with fueling on race day. Lately, I’ve been getting nauseous around the 5K point of the race (any race..even during a 5K I feel sick towards the end!) I’ve been keeping my same fueling that I would practice with – a banana, granola bar and coffee/water typically. I even tried to change it for my last half and only had juice with chia seeds in it, but I still got sick at the beginning of the race. Another note is that I eat/drink over 2 hours before race start, because I know that I have a weak stomach and struggle with cramps if I eat any closer to my run.

    Do you have any tips for me? Is it safe to not fuel at all before a race if my stomach can’t hold it on race day? Any other foods that you think would sit better?

    • 16

      I would practice, practice, practice your exact fueling strategy before long runs. Tweak variables such as the foods, amounts, and timing to see what works.

      While it’s “safe” not to fuel before a HM, it’s not ideal. And definitely not recommended before a marathon.

  10. 17

    Thanks for this post, Jason! I’ll be running my third half marathon in May and just started increasing my miles this week. In the past, I’ve used chews or gels about once per hour on any run over 8 miles and I increase my carb intake the day before a long run. I feel like what I really need during runs is salt more than sugar, though. That’s what I tend to crave, anyway. What do you think about using salt tablets and electrolyte drink (Nuun or coconut water are my faves) as fuel during a half marathon instead of gels? I’m hoping to finish in 2:25 to give you an idea of my pace. Thanks very much for your input!

    • 18

      Great question Lynn. Salt will never replace carbohydrate as a fuel (it doesn’t provide any “fuel”), but if you’re craving it then it’s a good idea to eat a little more the day before/morning of your race.

  11. 19

    This was AWESOME. I am running the DC Rock n’ Roll Marathon this weekend and it is my FIRST marathon. This post was perfect. Thank you Jason and Anne!

  12. 21

    So glad I read this post, Jason. I’m running my 15th marathon in April but feel like I’ve never nailed down the nutrition part. Eating 1-2 gels an hour feels like a lot but will try it on my next long training run. Will also increase carbs for the 2 days before. Hopefully I’ll notice a difference in the marathon. Thanks so much!

  13. 22

    I am currently training for a half at the end of April and working on getting more calories into my body…Lately my go to before long runs the night before is a sweet potato, protein, and veggies. The morning of is ALWAYS a bowl of steel cut oats with chia, fruit, and lots of nut butter. It what works for me and makes me feel strong on my runs!

  14. 24

    I am training for my first half marathon but usually run around a 13/14 min mile so I will be engaged in the event for 3+ hours. What do u recommend for nutrition in preparation days before and day of as well as during? Also, fluids? Any articles I should read? Should the gels be caffeinated? Thanks so much.

    • 25

      Hey Lisa,

      You can eat slightly more carbohydrate the day before the race, but otherwise there’s not much need to vary your fueling approach. Since you’ll be running slower, you’ll be burning a lower percentage of carbs.

      For fluids – start hydrated and drink to thirst. A little more if it’s hot out.

      Caffeinated gels – only if you like them and are used to them. I love getting a little pick-me-up, personally!

  15. 26

    Thanks for this info! I’ve been trying to figure out if I need to fuel during my next half (coming May 2). I’ve run several halfs to date but I have yet to break 2 hours. My PR is 2:05:33. I’ve been running much faster lately and I really think I have a chance this time at a sub 2, but fuel is my concern. I’ve typically always had an English muffin or bagel with some PB in the morning. My stomach is extremely sensitive and I don’t tolerate Gu or any of the good stuff. My longest run this training has been 9 miles. I had a failed attempt at it the day before the actual run (tight calf) so the 9 wasn’t exactly planned. I didn’t hydrate well the night before or morning of and didn’t have a good meal the night before. Once I decided I was going to give it a go, I had a piece of toast with PB. I managed to finish at 9:06 pace. I maintained the pace throughout for the most part. Miles 3 and 8 were my slowest, but knowing I only had 1 left, I kicked it up for 9. I have a small handheld water bottle (10 oz) that I use for my runs and I fill it half/half with water and powerade. All of that to ask, what can I do the days before to get myself fueled up enough that I can finish without crashing and avoid fuel during. Even without taking in anything, I was still rather miserable for a couple of hours after my 9.

    Thanks for any advice!


  1. […] my friends! I’m so glad many of you found the guest post on How to Fuel for a Marathon or Half Marathon yesterday helpful! Looking forward to seeing some of you out at Rock ‘n’ Roll DC this coming […]

  2. […] How to Fuel for a Marathon or Half Marathon […]

  3. […] 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 running nutrition tips if you sign up for the email list […]

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