Today’s post is about marathon fueling—what food to eat before, during, and after a marathon. It’s not solely about race day nutrition, because if you just focus on what to eat the day of the race, you’d likely have problems finishing. At the very least, your performance will suffer. You’ll probably end up regretting your life choices around mile 20 as your legs seize up and your stomach revolts at the sight of another gel.
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 individual who wants to check this off their bucket list? This is how I’d proceed. And this works equally as well for those of you who think a century ride (100 miles on a bike) or even a 140.6 triathlon might be in the cards. The basics are the same.
The Most Important Rule of Marathon Fueling
Well, the most important rule is probably “nothing new on race day.” Don’t eat anything during your race that you haven’t practiced with during training, lest you become a frequent visitor to the port-a-potties along the course.
But that’s not what I was referring to. I was referring to the necessity of becoming fat-adapted. As I explained in a previous post on how to train for a marathon, the number one goal of all marathoners is to become as efficient as possible at burning fat for fuel. The more fat you burn, the less reliant you are on sugar (glucose and glycogen) during the race, and the less likely you are to bonk due to low glycogen or hypoglycemia.
Becoming fat-adapted is a function of how you train—run intensity, mostly—and how you eat.
What to Eat Before, During, and After a Marathon
Marathon training isn’t just about logging the miles. You also need to determine through trial and error the fueling strategy that works best for you.
That might not be the same strategy your best running buddy or your favorite podcaster uses. Do you prefer to eat a bit more carb the night before or the morning of a long run? Do you like to start a run fasted, or do you do better with a small pre-run meal? What specific foods provide the most tangible energy? These are all questions you’ll have to answer for yourself The recommendations below are where I would start.
Should you run fasted or fed?
Doing at least some of your runs fasted can be a great way of signaling to your body that you expect it to tap into body fat stores. Fasted running isn’t mandatory, though. If you try it and hate it, eat. A decent rule of thumb is to go fasted for runs lasting less than an hour and practice fueling in runs longer than that. I wouldn’t plan on trying to do an entire marathon fasted. It’s just too long and too demanding.
Remember that fasting can put you in a ketotic state, especially when paired with exercise, even if you aren’t following an extremely low-carb diet. That means you should be extra mindful of your hydration and electrolyte status. Add salt or an electrolyte product to your water. Salt your food liberally.
Fueling during the off-season/way out from your race
This is the time to focus on building your aerobic engine, training your body to run off the fat you’re carrying around (yes, even if you’re objectively lean).
If you’re already a practicing Grok, eating Primal foods and following the Primal Blueprint lifestyle laws, the metabolic foundation is already laid. Keep doing what you’re doing. Those coming from a place of SAD eating and carb-dependency have more work in front of them. Ensure meat, fish, fowl, eggs, produce, nuts, seeds, full-fat dairy, and Primal-approved fats comprise your meals from here on out.
Now’s also the time to try keto if you want. Despite what you may have heard, endurance athletes can absolutely train and compete at a high level on a keto diet. Undertaking this metabolic shift can lead to low energy and dips in performance, though. These are temporary, but it’s best to get them out of the way in the off-season.
Otherwise, keep carbs right around 150 grams per day. That may sound like a lot if you’re coming from the lower end of the carb continuum, but that’s still considered low by conventional endurance sports standards. Heck, at the height of my marathon training, I was blasting through upwards of 700 grams each day. Stick to approved Primal sources, of course: yams and sweet potatoes, squashes, fruit, white potatoes or rice if tolerated.
In the three months or so leading up to the race
Continue to eat Primally. If you’re feeling great and performing well on keto, there’s no reason to stop.
Start to experiment with your run fueling strategy—what you eat before and during your runs, as well as after to help you recover. Try out different levels of carb intake, within reason, and different sources of carbs. Maybe you run great on sweet potato or a banana. (A 6-inch banana has around 25 grams of carbs.) Play around with the fueling options below to see what sits well in your stomach.
In the days leading up to the race
Start eating more carbs unless you intend to stay in a ketogenic state. 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. Just eat twice the amount of carbs you’ve been eating. Instead of one sweet potato with dinner, have one with lunch and one with dinner. Eat the whole banana instead of half the banana. You can easily stick to starchy roots, tubers, fruit, and even rice to pack those muscles full of glycogen.
Maintain your protein intake and moderate your fat intake, but don’t restrict calories here. And don’t do any hard training during these last two or three taper days. Maybe some light jogging or walking.
What to eat on race day
By the time race day rolls around, you should know what suits your body best. Stick to the tried and true.
My go-to is: two hours before the gun goes off, eat a light breakfast with some representation from all the macronutrients. Maybe a few eggs and a banana or 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.
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, then increase the pace a bit later. Be wary of treating the aid stations as a free buffet. Unless you feel very confident that the items on offer won’t cause GI distress, it’s safer to carry your own fuel and hydration concoctions.
The temptation to gorge yourself will be strong. Maybe not immediately upon crossing the finish line, but once you recover your senses. There’s no harm in a celebratory meal—you earned it. In the days that follow, focus on replenishing, nutrient-dense foods. Consume plenty of protein. I’d also do a few scoops of collagen each day.
Mid-run Fueling Options
Option 1: Go for simple
Simple sugar, that is. 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 into the event, taking 20 grams of glucose every 20 to 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 (drink water at every aid station and/or carry your own) as well.
If you plan to go with this strategy, testing it in a couple long runs will suffice. No need to consume straight sugar every time you hit the road.
Option 2: Run on real food
This seems to be an increasingly popular approach among runners. I’ve even known runners to take along a pouch full of bacon. That’s certainly one option. Here are some others that are less likely to get you chased by a pack of neighborhood dogs.
Chia pudding made with coconut milk and sweetened with maple syrup or carried in a resealable food pouch or baggie
Store-bought baby food pouch
Pancakes or waffles made with grain-free flour
Nut butter and jelly or honey on aforementioned pancakes
Option 3: Commercially available sports nutrition products
Peruse the fueling section of your local running store and see what’s available. More and more companies are making products for runners who are particular about the quality of their carbs. Muir Energy gels, for example, are made with raw coconut palm nectar and blackstrap molasses. (I’m a particular fan of blackstrap molasses for its minerals and electrolytes.) Other products, like UCan and SFuels, specifically cater to runners who are focused on fat-burning.
Option 4: Exogenous ketones
Exogenous ketone products are possibly worth trying if you’ve already done the work to become keto-adapted. My own experience was not entirely positive, but some athletes swear by them. They aren’t cheap, though. A more affordable option is MCT oil, which can also boost ketone levels when added to your morning coffee or homemade energy gels or slurries. Don’t overdo it, lest you spend the greater part of your run searching for a bathroom.
What Else Should You Consider?
As I said already, training for a marathon entails much more than strapping on your fancy running shoes and pounding the pavement. Training your metabolism to burn fat efficiently is just as important. It may even be the determining factor of whether you make it over the finish line. Hydration and electrolyte management matter too. Novices should give themselves plenty of time to train—and to make mistakes during training. I can give you all the advice in the world here, but much of this comes down to trial and error.
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 rucking. But many of you will not. Many will get the endurance bug, and it’s a pernicious 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.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.