Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
7 Dec

How to Fuel a Marathon

Having yielded to those of you who still insist on running a marathon, yesterday I offered a training strategy that gets you the best results with the least amount of damage. Today’s post is about fueling a marathon – what food to eat and when to eat it. It’s not solely about race day nutrition, because if you just focused on what to eat the day of the race, you’d be missing out on a lot (and you’d likely have problems finishing, or at the very least your performance would suffer). It’s about what to eat while training, a few days before the race, and the day of the race itself. This is the stuff I would do if I had to go back and do another marathon with my current knowledge. I might tweak things slightly if I was trying to make the Olympics, but for the average, relatively fit Primal dude or gal who wants to check this off their bucket list? This is the perfect way to fuel your efforts. And this works equally as well for those of you who think a century ride (100 miles on a bike) might be in the cards.

First, let’s examine what to do while you’re training. What do you eat? How much of it do you eat? Low-carb, high-carb?

Train Low, Race High

For the layperson, “train low, race high” is basically a way to teach your body to do without a glut of glucose for longer periods of time. By training low on glycogen, your body grows accustomed to running on fat and conserving muscle glycogen. By training low and then racing high – with topped-off glycogen stores in your muscles – you experience a big boost in performance on race day. You’ve built up your ability to access body fat during a run, and that doesn’t go anywhere, but now you’ve suddenly got 400+ grams of muscle glycogen at your disposal. Glycogen that you’ve learned to access efficiently, rather than squander all at once. That’s huge, especially for 26.2 miles.

It’s reasonable to think that Grok often “trained low.” If low-level physical activity in a glycogen-depleted state was the norm for much of human evolution – as I think it probably was – it makes sense that its emulation in modern times would confer performance benefits. It makes sense that our bodies would conserve energy and streamline energy pathways, and that taking advantage of these physiological truths will give us enough of a racing edge without compromising our health – since we’re training “with” our physiology, rather than in direct opposition to it.

There’s been limited modern research on “train low, race high,” and it’s pretty compelling. One study found that athletes who trained twice a day on alternate days and thus had lower muscle glycogen during the second training session almost quadrupled their muscle endurance, while athletes who trained once a day on consecutive days barely doubled theirs by study’s end. Both groups of athletes performed the same amount of volume and intensity, but only one group went into every other training session with depleted glycogen – and that group saw the greatest benefits to both work capacity and energy efficiency (glycogen and fat).

During your training, keep carbs right around 150 grams per day. That may sound like a lot, especially if you’re coming from the lower end of the carb continuum, but rest assured that 150 grams of carbs is a paltry amount for most endurance athletes. At the height of my training, I was blasting through upwards of 700 grams each day. As I mentioned yesterday, increase your carbs the day before – and morning of – your interval training, because much of the benefit from intervals comes from glycogen depletion, and you gotta have glycogen in your muscles before you deplete it. But for the most part, keep carbs at a moderate (for Primal folks) to low level. Stick to approved Primal sources, of course:

And remember: you’re training. Your performance during a particular run on a particular training day might not go great, but you’re in this for the long haul. You’re in this for the race day boost. It’s not a competition. You’re not trying to beat the other guy (because there is no other guy), you’re trying to train your mitochondria and your energy utilization pathways so that when the time comes, when the event rolls around, you are fully prepared to give it your best showing. Keep it in perspective and don’t beat yourself up too much. One final thought on training: it’s always better to start your race slightly undertrained than over-trained.

Couple Days Before the Race

Start eating more carbs. This is the classic carbo-load, and no, it doesn’t have to reach Phelpsian levels of mayo-and-egg sandwiches on white bread, kilos of pasta, and flagons of cheese grits. You can easily stick to starchy roots, tubers, and fruit (and even rice) to pack those muscles full of glycogen. Maintain your protein intake and moderate your fat intake. You’re looking to maximize muscle glycogen stores.

Just eat twice the amount of carbs you’ve been eating. So, instead of one sweet potato with dinner, have one with lunch and one with dinner. Eat the whole banana instead of half the banana. Aim for about 350 grams of carbs per day. And don’t do any hard training during these last two or three taper days. Maybe some light jogging or walking.

Race Day

If you have two hours before the gun goes off, eat a light breakfast with some representation from all macronutrients. Maybe a few eggs and a banana, maybe half a yam. Nothing that sits heavy in the stomach, and make sure it’s something you can digest. If you are a coffee drinker, a cup today will help mobilize fatty acids. Don’t go zesty, don’t experiment with something new. Stick to the tried and true. If you didn’t spend the last couple of days fueling up, the most optimal race day breakfast isn’t gonna save you. Sorry to say it.

During the race, maintain your composure. Your glycogen-replete body is going to feel eminently powerful. Try not to go too fast too soon. Better to start a bit slower, get those fats into the muscle cells and then increase the pace a bit later. As for mid-race fueling, I’d forgo the usual Gatorade offerings on the course and stick to the rocket fuel found in pure glucose. Some companies sell straight glucose polymer powders (complex carbs as maltodextrin) you can mix with water to your own desired consistency and carry with you on a fuel belt. This is the one time in your life that straight glucose is your friend. The method I have recommended for 20 years is to start refueling at about an hour in to the event, taking 20 grams of glucose every 20-30 minutes. This puts enough glucose into the bloodstream to help fuel muscles without interfering with the intended fat combustion – and it “unburdens” the muscles from having to give up too much glycogen too soon. Be sure to drink enough pure water (usually offered on the course, so you don’t have to carry that) as well.

Now, if you are so inclined, you can also make your own version of a sport drink/energy gel hybrid. It may not be astoundingly delicious, but it’ll get the job done. Here’s how to do it:

  1. Slightly heat some coconut water on the stove. Don’t let it get anywhere near simmering. Just let it get warm enough to melt the next three ingredients easily.
  2. Add a few dashes of sea salt, preferably one with high mineral content. Sea salt provides sodium, an important electrolyte, plus trace minerals. You’re going to be burning through a lot of it during the race.
  3. Add honey, preferably raw and from a local farm (remember, many store bought honey isn’t actually honey anymore).
  4. Add blackstrap molasses. Blackstrap molasses comes after the third boiling of sugar cane. It contains less sugar than either white sugar, brown sugar, regular molasses, or dark molasses, but far more minerals and electrolytes. See, sugar cane is a plant with roots that stretch deep into the soil to extract nutrients (some research suggests sugar cane roots may go down as far as six meters). Very few of those nutrients make it into white or brown sugar, and regular and dark molasses contain some, but it’s blackstrap molasses which gets the bulk of the minerals. So, when you add just a couple tablespoons of blackstrap molasses to your energy drink, you’re getting more than twice the potassium than a banana, more calcium than a cup of raw spinach, and almost 100 mg of magnesium.
  5. Mix it all together until everything melts and it’s a dark brown murky viscous fluid. I didn’t include specific amounts, but start with a couple tablespoons of each sweetener and the juice from one coconut (or one carton of coconut water). You’ll be cruising for the first bit of the race, thanks to your effective pre-race training and fueling, but when you really start dipping into your glycogen stores, having a banana or two and a bottle of high-potency Primal energy drink will prove useful.

Good luck. If you train and fuel smartly, you won’t really need any luck at all, but I figure it’s a nice thing to say regardless.

Once you’re done with the marathon, I’d move on to different things. Try rock climbing. Try mountain trekking. Heck, try an ultra marathon, but do it at an even easier, fat-oxidizing pace. But many of you will not. Many will get the endurance bug, and it’s a nasty one. This method of training and fueling is not a cure for the bug, but it will negate some of the worst symptoms. If you do try my training and fueling recommendations, let me know how you do. I’m especially interested in knowing how they compare to performances using other methods.

Take care, and be sure to leave a comment! Thanks for reading.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Hi, I’m curious what you would say that’s different for an Olympic athlete. I’m training for 2016. Thanks!

    Erin wrote on August 1st, 2012
  2. 2 months ago I decided to run my first marathon, and this isn’t something to come natural to me being an endomorph type. I am 41 and running for about a year now. To run this marathon, I have to reduce body mass (at least 20 kg or so), so I decided to go low carb. Painful as it was in the beginning, I am now convinced that this is the only way to go for people like me, as it allows to tap into the body’s energy resources and every other regime won’t cause a drop in weight while at the same time allowing to train hard. One can’t train hard on a reduced energy intake diet! Now, as far as training goes there is a lot of experimenting possible, but as for the competition, one wants to play it safe. Having experimented with general low carb diet training and high carb long runs, I have to admit that I am not convinced that doing a day or two of carboloading prior to a long run (competition) is the best thing to do. And here’s why. Carbohydrated make the body retain water. So what happens is that I gain more weight in fluids, which are then not released over the course of the entire run, but right in the beginning.

    Also, I agree to consume carbs during the long run/competition, but how much water would I drink? Too much would caused me to see the loo too often at best, while it could enforce dehydration at worst.

    Any advice, suggestions, personal experiences? Thx.

    Simon Adventures wrote on November 25th, 2012
  3. Mark- Why are you recommending maltodextrin rather than dextrose. My doc told me that Dextrose is the pure glucose and maltodextrin isn’t. Can you clarify this for me or are they both acceptable? Thanks!

    John Van HOrn wrote on March 2nd, 2013
  4. I sure am hoping I am going to feel powerful come race day because my runs have really slowed down. Yesterday I hit the wall at 13 miles. I am convinced that it is because of my low carbs, has anybody else had similar experience?

    John Van Horn wrote on March 3rd, 2013
  5. Great thank you. I’m loving off road half marathons and really enjoying using ‘real’ ingredients to fuel them. :)

    Jane wrote on March 6th, 2013
  6. I did my test run this saturday the week before my marathon and I took about 1.5 to 1.75 minutes off my mile. I messed around with a dextrose and matlodextrin to fuel this practice run. I will be thrilled if I have the same energy come race day, but I had to give it a practice run.

    John Van Horn wrote on March 11th, 2013
  7. I’m confused about something. I thought Ketosis was binary? ie you are either in Ketosis and burning your fat for fuel or you’re not. Wouldn’t the insulin spike from the carbs prevent you from accessing your fat stores? Doing a 5km swim on Saturday so am really interested to hear comments on this.

    David Harley wrote on April 25th, 2013
  8. loved coming across this. My second marathon is in 2 days….yes, I caught that endurance bug. wanted you to know I’m taking your advice and hoping to shave 20 minutes off my time. I’ll let you know how it goes–may even get crazy and make a batch of my own gel hybrid. woot.

    Vicki wrote on April 25th, 2013
  9. Loved coming across this…I am doing a half marathon in a little over a week. Started eating paleo about three weeks ago and feel amazing!!! Love not craving nasty sugary foods!!! Is there anything wrong with just having a bag of rasins ad a snack while running…I’m afraid I will hit a wall mile 10…will they give me enough energy??

    Elizabeth wrote on May 16th, 2013
  10. I have been doing low carb for about half a year now – for me, that means anywhere from 30 to 150 per day usually. I don’t pay attention to ketosis, but I know I am at the least fat adapted because I can now go long periods of time (16 hours or so, although I’ve gone 20) without getting hungry really.

    I train in the morning or early afternoon usually, on just coffee and coconut oil/mct oil. So whether I am lifting weights or running, I have become used to exercising without carbs.

    I recently completed my first half marathon since making this dietary switch. I had coffee with mct oil and coconut oil in the morning, and that’s it. I had completed as far as a 14.5 mile run in my training at a 9:20/mile pace or so on just the coffee and coconut oil, with consistent energy even at the end, so I knew it was doable. However, I had my doubts about whether I could race (i.e. push harder) without the carbs, so I ran with a powerbar gel thing in my hand just in case. I strategized ahead of time that I would need to run consistently, because I probably would not have much of a kick at the end (I’ve learned my body does need carbs to really, really push it, so for a shorter race like a 5k, I would have glucose before).

    I did not need the gel pack at all. I completed the half in 1:41:08 with consistent energy; my time would have been even better if my knee had not started hurting around mile 8 (time to replace my shoes I’m thinking).

    However, one thing to note – I did “carbo-load” so to speak in the few days before. I made a conscious effort to eat sweet potato and plantains, so my carb intake the day before was probably around 400g. I am not sure if this helped me or not, but I decided to do it based upon Mark’s recommendation in this article. I’m thinking it probably did.

    The one thing I did not do that the article recommends was have a balanced breakfast the morning of; I had considered it but I didn’t want to get up even earlier than I had to already, and since this is something I never did for any of my training runs, I was a little worried about it affecting my stomach.

    While running, I think I only had about 4-6 oz of water; I stopped twice and threw a little in my mouth for one swallow each time. I didn’t want to bother my stomach or have to go to the bathroom, so this strategy worked for me. Immediately after the race I drank about 32 oz of water, and about 8 oz of some sports drink (not the best choice, but none of the post race food – pretzels, gummy things – were things I wanted to put in my body). When I got home, I had a shake with pumpkin, vega sport protein (I can’t have whey/casein/soy etc), and mct oil.

    So, the main take aways:

    – I wanted to share my experience because I was looking online for other people’s experience with low carb half-marathons/marathons, and did not find a whole lot

    – running a longer race without carbs when fat adapted is definitely do-able; increasing your carbohydrate intake in the preceding days may or may not really help you. It certainly didn’t hurt me, so I will probably do it again before my next race.

    – this approach may not be for everyone; if you are going to try it, maybe don’t do it in a race you really care about PRing in, and also have a back up (i.e. carry a gel or a primal glucose-rich snack with you in case you feel like you are crashing)

    Laura wrote on June 9th, 2014
  11. So I’m not losing my mind! I adopted Paleo 10 wks ago and have done several workouts fasting, I’m running a half Marathon on Saturday…did my last long run (11 miles) last Wednesday on an empty stomach. My pace was great, I was hungry when I got home but still showered and got my kids on the bus before I was able to eat anything. It was almost weird to not feel like I needed food.

    Bekah wrote on October 7th, 2014
  12. Hi, I was wondering, where you say drink 20 grams of glucose every 20-30 mins when refueling in a marathon; how do I know how much this is of my drinks bottle? Thanks.

    Catherine wrote on April 1st, 2015
  13. I wish I had seen this post earlier in my training. I’ve got 3 weeks to my marathon and have been experimenting with paleo nutrition bars. I was debating adding glucose polymers to the no-bake bars and found this post.

    I look forward to integrating these tips into my training and race day nutrition. Thanks, Mark!

    Evangeline wrote on May 12th, 2016

Leave a Reply

If you'd like to add an avatar to all of your comments click here!

© 2016 Mark's Daily Apple

Subscribe to the Newsletter and Get a Free Copy
of Mark Sisson's Fitness eBook and more!