Fueling and Hydration for the marathon (condensed version)

[As featured in the OKC Landrunner’s Newsletter for April 2012]


One of the biggest questions I get asked as an elite marathoner is, “What do you eat/drink?” Having been marathoning for 5 years now (and prolific marathoning the past 14 months), I’ve learned a lot about myself and the general rules-of-thumb for fueling/hydration before, during, and after a marathon. Seeing that we’re closely approaching the OKC Memorial Marathon, I thought I would share what I’ve learned!


The biggest factor leading up to a half marathon/marathon is trying to maximize your glycogen stores. You can store approximately 2000 kcal/500g of glycogen (and possibly more), which equates to roughly 2000 kcal/100kcal burned per mile= 20 miles-worth of stored glycogen. However, running at marathon pace, you’re not burning glycogen exclusively (~likely closer to 90%), so you technically have enough stored glycogen for around 22-24 miles. The key is trying to get as close to your max as possible before the race, so you don’t have to be as-reliant on fueling during the race.

My general rule of thumb with fueling and hydration pre-marathon is… as you taper, keep your daily diet normal, but consume a greater percentage as carbohydrates. You definitely don’t want to be stuffing yourself silly with food! Because of the taper, you will naturally store up more glycogen. Glycogen is the stored form of glucose, which consists of water + carbon. It will make you feel full, but as it’s broken down during the race, water will be liberated (also helping with hydration of cells).

I focus on “carbo-loading” during the 2 days prior to a marathon. You can experiment with this yourself, esp. if you’re not used to consuming this many carbohydrates.

One thing I learned from the registered dietician last year is– you want to consume more simple-sugar foods rather than complex, high-fiber carbohydrate options. The reason for this is fiber makes you feel full, and you won’t store up as much glycogen. This means choosing ~white bread, white rice, cream of rice, white potatoes, and white pasta, instead of the whole grain options. You can also choose ~juices instead of fruit. There’s nothing wrong with soda and candy either! All the foods that are normally perceived as “bad” (~donuts/cinnamon rolls, fast food, candy, soda, and white bread), are actually GREAT for carbo-loading for the marathon (~sugar, sodium, fat)!

For pre-race breakfast (YES, you should absolutely eat breakfast!), you want to consume what you normally eat and is easily digested. You want to get 50g of carbohydrates per hour before the race. For example, if you like to eat 2 hour before a marathon, you should get ~100g/carbohydrates. Personally, I like to eat a light breakfast 90 minutes before, which works out to 75g. Depending on your personal preference, some food suggestions include ~energy bars, toast (with a little peanut butter), cereal, oatmeal, cream of rice, honey, Powergels, rice cakes, pancakes, fruit, Gatorade, and nothing wrong with a cup of coffee and a bunch of sugar!

I’ve learned I feel better with a little more protein for breakfast, which helps to balance my blood sugar. Same goes for other meals as well—make sure you’re eating balanced meals and not exclusively carbohydrates. Since I travel frequently, I’ve had great success with Powerbar Harvest Bars, which is a well-balanced energy bar. 90 min. before a marathon, I’ll have a Harvest Bar, banana, cup of coffee with milk and sugar, and some water and Gatorade. I like to travel with my breakfast foods (including my normal instant coffee), snacks, honey, and even sugar. I’ll usually sip on some Gatorade and water leading up to the race start.

As for caffeine, yes, it’s absolutely an ergogenic aid. Not only is it a stimulant (which can help with concentration during the later stages of a marathon), but it also can help with breathing and has a glycogen-sparing effect. However, it’s also worth noting that caffeine can have unwanted side-effects on the gut, so you should experiment. There are various thoughts on how to best go about getting the ergogenic effect. I highly recommend the following article: http://www.powerbar.com/articles/218/caffeine-and-athletic-performance.aspx Through experimentation, I’ve found that I do well with either ½ a No-Doz or 1 Excedrin, 1 hour before a marathon with Gatorade. Then, I’ll take 1 more Excedrin at around ~16 miles to help “boost” my concentration.

Lastly, if the race is going to be hot, it’s recommended to consume more sodium leading up to the race. I’ll use the salt shaker on foods and drinks, and also consume Gatorade Endurance Formula (which has more sodium).

 During the race

There’s several rules-of-thumb on fueling and hydration during a half marathon/marathon. For fueling, you want to make sure you’re getting 30-60g of carbohydrates per hour (your choice of how to get the carbohydrates). If you’re a good “fat burner” (as I am), you could get away with consuming on the lower end of the spectrum. Also, if you’re consuming a glucose:fructose blended fuel (~2:1 ratio, like Powerbar’s C2Max blended gels/fluids), you can possibly consume/digest up to 90g of carbohydrates/hour. I’ll usually take in 30-45g/hour– Vanilla Powergels at around 7 miles, 14 miles, and 21 miles (with water)—I’ll get additional carbohydrates through fluid consumption (~Gatorade Endurance Formula).

It’s recommended to practice and through trial and error, figuring out what type of gels/fuel your gut tolerates best.

For fluid consumption, I recommend reading Powerbar’s Nutrition playbook: http://media.powerbar.com/playbooks/290_running_playbook_3_11.pdf Research shows if you lose 2-3% of your body weight, your performance starts to suffer. Powerbar.com says you need 13-26 fluid ounces/hour, depending on individual needs/conditions. The research shows that most athletes do fine with on average ~16 fluid ounces/hour. What works for me is to “drink as needed” and “get a little at a time”—I’ll alternate sipping on water or Gatorade Endurance Formula (or whatever the race offers) every 2-3 miles (making sure I get in water with my gels, and Gatorade in between).

I previously blogged in great detail about measuring your sweat rate to determine your fluid needs: Fueling and hydration in the marathon While this is helpful information to know about yourself, what I learned through my own trial and error is: I feel terrible trying to match my sweat rate!

I did some more research, including inquiring with the Chief Physiologist at the Olympic Training Center, Dr. Randy Wilber, and also reading Dr. Noake’s book, Lore of Running. Both of them talked about how the gastric empyting rate lags behind your sweat rate— you basically can’t absorb/replace fluids at the same rate as it’s being lost.

You likely go into a race a bit heavy because of the carbohydrate loading. When you break down glycogen… you liberate water for cells. As you break down glycogen/lose sweat (plus replacing it), you’ll likely end up at (or close to) to your normal weight. Therefore, while sweat rate is good to know…. It’s not necessary to try and match it. If you “drink as needed” and get somewhere between 13-26 fluid ounces/hour, you’ll likely be Ok. It is worth noting that the bigger/heavier you are, the more sweat you’ll lose.

Some people are heavy sweaters and likely need more sodium than others. If you consider yourself a “heavy sweater”, you should experiment with salt tablets such as ~Lava Salt. I like Gatorade Endurance Formula because it has more sodium and a little bit of calcium and magnesium to help with muscle function.


So you’ve finished 13.1 or 26.2 miles (Yeaaaa, congratulations!)… Now is the time to pig out and enjoy yourself, if your gut can handle it! Definitely, getting in quality protein is important, along with hydration (and this goes for several days after a half marathon/marathon). Hopefully the race has post-race food-of-substance, but if not…. Nothing like finding a good hamburger, fries, and beer to re-grease the engine! Sometimes all my gut can handle immediately after the race is fluids. Within 15 minutes after a marathon, I try to get in a Powerbar, a water bottle filled with Emergen-C, and an iron pill or two (to counter all the footstrike hemolysis).

I appreciate donations for my free advice! I write with my heart and desire to help others. Your contribution will help cover my running-related expenses as a full-time professional runner. Thank you!



  1. I’m getting ready to run a 50K and found this post helpful! I’ve been looking for info on whether it’s a good idea to carb-load or not. Thanks!

  2. Check out Noakes latest book Waterlogged. Unless you are drinking in excess of thirst, maintaining or gaining weight, your blood sodium levels should remain constant or increase. No need for salt replacement until afterward. http://www.daveelger.net/2008/06/is-salt-intake-necessary-during-ultra.html

    • runcamille says:

      Hi Dave! I LOVE Noakes. Lore of Running was actually my first running book ever… in junior high! I still refer back to it and read ‘pearls of wisdom’, that I obviously didn’t understand at the age of 13!

      I’ve experimented a lot with the whole sodium thing. I think my problem, personally, is that I eat a lot of natural foods that are low sodium. Consequently, I wasn’t getting enough sodium to help retain fluid and stay hydrated (like a camel!). I also think I generally don’t drink much water, or not as much as I should. I consulted with the Chief Physiologist from the Olympic Training Center, Dr. Randy Wilber, and he gave me a lot of pointers pertaining to sodium and fluids. I’ve felt MUCH BETTER since making a concerted effort to get more sodium in my diet. I gave advice to a local friend about the sodium, and he said he didn’t cramp at all in an ultra (said he normally has problems with cramping). I’ve never taken sodium in a race, but my ultra runner friends swear by it.


  1. […] quick energy for your muscles/brain. By simple sugars, I mean what I talked about in my post about pre-marathon fueling and hydration– you want to consume “white foods”, juices (ideally, instead of fruit– but […]