Eating for a Marathon: How to Fuel During Training and on Race Day

Do you guys remember Kyle Pfaffenbach, nutrition consultant for the Brooks Beasts Track Club, who shared the best foods for runners? Well, he’s back — and this time he’s sharing his best tips on eating for a marathon!

Eating for a Marathon: How to Fuel for Your Best Race

Obvious fact #1: The half-marathon and marathon are sustained endurance events. This means that for the half marathon, unless you are Zersenay Tadese (world record half marathon in 58:23), you are going to be running for over an hour. For the marathon, even if you are Wilson Kipsang (world record marathon in 2:03:23), you are going to be racing for more than an hour.
Obvious fact #2: Everybody wants to do his or her best on race day.
So how are these two facts related nutritionally? Well, in order to perform your best in races that last more than an hour, you have to take on supplemental energy throughout your race. During longer endurance events our bodies “run out” of muscle glycogen and liver glycogen (glycogen is the storage form of glucose). Because glucose and glycogen are required as fuel to produce our strongest aerobic efforts, we want to have high glucose availability throughout the race. This requires consuming glucose regularly during the race.

How to Fuel for a Marathon in 3 Steps

1. See what nutrition the race will offer. Step 1 to prepare nutritionally for a long race: check out what drinks and gels the race will be offering at aid stations. Most races will offer energy gels and an electrolyte drink. Both of these are excellent sources of glucose during a run, and it is a matter of preference which one(s) you want to utilize. Personally, I stick with Gatorade over GU, because the GU is not very water-soluble and can be tough to get down when you are running hard.

2. Try out the products that are offered at aid stations during training runs! This goes for your long runs (obviously), as well as a few tempo runs and even track workouts. This will help get your gut used to these forms of nutrition at a variety of intensities, all of which will provide insight into what works best for you. Ultimately, this will provide peace of mind that your race day nutrition will agree with you no matter how hard you push it.
Once you have established what you are going to be consuming during the race, the next step is to establish when you are going to take on your glucose.
3. Take on glucose early and often. The “early” part of this step is important; you don’t want to wait until the tank is empty to start putting more fuel in.
Allow me to make an analogy. It is January, you just finished a long-run, it is snowing lightly, and you are recovering by soaking in an outdoor hot tub dreaming about the PB you are going to throw down. With this particular hot tub, you control the amount of water flowing into it as well as the amount flowing out of it. As you are sitting there, you notice the water level is dropping, and it is due to a decrease in water INPUT. What do you do? You are not going to sit there freezing and wait for the water to reach the bottom of the hot tub and THEN turn up the flow of water. You are going to turn up the input to match the output as soon as the water level begins dropping.
This example is a long-winded analogy for carbohydrate intake during a marathon or half-marathon. At the 3-mile or 6-mile mark, you are not completely out of glycogen yet (i.e. the water is not to the bottom of the hot tub). But, it would be a lot more comfortable NOW and LATER to keep your carbohydrate (i.e. hot water) levels up.
The reason for wanting to maintain high glucose levels during your race is two-fold. First, as discussed above, supplementing glucose spares liver glycogen and can also be used to fuel working muscles. The second reason is that consuming carbohydrates early on during a long race or training run is a way of assuring the brain that despite the rapid rate at which energy is being gobbled up, there is no need to worry — there is always more where that came from!
Allow me to make you suffer through another analogy: Not taking on carbohydrates early would have your brain worrying like your significant other if you arrived home one day unannounced in a brand new Ferrari. Their thoughts would probably go something like: “You’re crazy. We can’t afford that. Take it back and DRIVE SLOW.” In contrast, their attitude would probably change if you calmly informed your significant other not to worry because you just won the lottery.
Taking on carbs early during a race or hard workout is like telling your brain you have the money for the Ferrari, and you can go as fast as you want. Sure, you are burning through energy at an unsustainable rate, but look, there will be more and more where that came from. This is not an insignificant point in my opinion. Taking on your nutrition “early and often” gives you the best chance of avoiding central nervous system fatigue (i.e. your significant other flipping out because you bought a Ferrari). This strategy represents your best chance of keeping hormones in balance and motor units firing until the end of the race.
Bottom line recommendation (FINALLY): consume 6 to 8 ounces of Gatorade or one GU every three miles, starting at the 3-mile mark. You should also start implementing this strategy on your long runs leading up to race day. If you don’t already do this, you are in for a treat.

What to Eat During Marathon Training

The last topic I want to touch on is regarding daily nutrition leading up to your half or full marathon (and I promise I will be more parsimonious with my words here). In addition to the standard advice of eating whole foods, consume the proper recovery nutrition, and get lots of fruits and vegetables, I would also recommend that in the week leading up to the race you consider increasing your percentage of calories that come from carbohydrates. Because glycogen stores and glucose availability are so important to high-intensity endurance races, it is important to make sure you have topped off the tank. Sweet potatoes are a great source of complex carbohydrates and adding a few sweet potatoes into your dinners the pre-race week is a great way to go.

What to Eat the Morning of the Marathon

On the morning of the race, I would recommend eating a balanced pre-race meal with plenty of carbohydrates, three hours prior to the race. This tops off liver glycogen and provides enough time for postprandial processes, such as an increase in insulin, to return back to normal. At that point you are good to go! You can take some Gatorade or GU immediately prior to your warm up if you prefer or wait for the 3-mile aid station to take on some nutrition (but no later!).
Thanks for the tips, Kyle! What are a few of your favorite eating-for-a-marathon tricks? —Jenn

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1 Comment
  1. Great piece!
    Fueling is so very important if you want to run to your full potential.
    Fuel My Run can help runners adhere to your mid-race fuleing recommendations.
    Thanks again.