Fueling the Marathon: What my first marathon taught me about nutrition, grit, and respecting the distance.
There is something about your first marathon that stays with you forever.
I thought I was prepared for my first marathon. I had trained the mileage, put in the long runs, the hours. I showed up to the start line of the Vancouver marathon on May 3rd, 2023, feeling confident. The marathon has a way of humbling you. It has no mercy and exposes every weakness. For me, that weakness was nutrition. I learned very quickly that you cannot out-train poor fueling. When you ask your body to carry you through 42.2 km, every decision leading up to the moment matters. Unfortunately, I had treated fueling like an afterthought, and I learned the impact of that decision the hard way. Proper fueling starts well before you start your race and continues long after you cross the finish line. The before, during and after all work together. When one piece is missing the effects usually show up somewhere along the course. Unfortunately, I under-fueled in almost every area.
No one forgets their first marathon, and I won’t forget mine. Sometimes the toughest race becomes the most important one. Vancouver taught me about glycogen depletion, gut training, pacing mistakes, cramping, mental strength and how quickly things can unravel when you don’t properly fuel the work you are asking your body to do.
When people talked about carb loading, I honestly didn’t make it a priority. I remember eating multiple muffins on the drive up to the race and thinking that was probably “good enough.” It wasn’t. A lot of the marathon is decided before you even reach the start line. You can have the training, the motivation, and the race-day adrenaline, but if your body is not properly fueled going into the race, it eventually catches up to you. Proper carb loading is not just eating a large pasta dinner the night before. It is a process of preparing your body’s energy stores in the days leading into the race. Research shows that maximizing glycogen stores happens over roughly 2–3 days leading into the race.
For endurance athletes, current recommendations generally suggest:
8–12 grams of carbohydrates per kilogram of body weight per day
The goal is to fully saturate muscle glycogen stores, so your body has enough accessible energy to sustain your prolonged effort.
Examples of good carbohydrate sources during carb loading include:
Of course, at the top of the list:
Oats
Rice
Potatoes
Bagels
Pasta
Fruit- Be careful as fruits are high in carbs but also high in fiber. Too much can cause stomach troubles midrace.
The mistake many runners make is under-eating because they reduce training volume during taper week and suddenly feel “less hungry.” But the body is trying to store fuel and the marathon requires a lot of it.
Even though I hadn’t properly carb loaded, I still felt strong heading into race day. I went out feeling incredible. My goal was to run sub-4 hours and through the first 21 km, I was ahead of pace. Mistake number two, but pacing is a lesson for another post. Around kilometer 30, everything changed. I could feel it coming, “the wall”. Carb loading helps fill your glycogen stores before race day, but those stores are still limited. Your body is burning through those stores throughout the marathon, especially as effort levels rise and fatigue starts to build. This was another area where I underestimated the demands of the marathon. I was burning through energy much faster than I was replacing it. My glycogen stores were depleted, my legs were tightening, and I realized I was running dangerously low on gels. I had only been taking one gel approximately every 45-50 minutes. The problem? That wasn’t enough for the effort level I was asking my body to sustain.
Most current sports nutrition guidelines recommend marathon runners consume approximately:
30–60 grams of carbohydrates per hour
Up to 90 grams per hour for highly trained athletes who have trained their gut to tolerate it
Many gels only contain around 20–25 grams of carbohydrates each. Meaning I simply wasn’t taking in enough fuel to support my pace and output. Once glycogen depletion hits, recovery becomes incredibly difficult. The final 10 km became one long mental battle. The lack of fuel caught up with me. My pace dropped. My body was starting to shut down. My body had burned through most of my glycogen stores. My GI system was a mess. Another lesson learned: You must train your gut. Race-day nutrition should never be a surprise to your body. I didn’t spend enough time practicing nutrition during training. I went from eating things like baby food on long runs to suddenly relying on gels on race day without properly testing them. The gut is trainable, just like your legs and lungs are.
During marathon training, runners should practice:
Timing of gels
Fluid intake
Electrolyte intake
Carbohydrate amounts
Types of fuel used
Pre-run meals
Your body will adapt over time. The thing about hitting “the wall”, it is not just physical exhaustion. It becomes mental too. Every km feels like 10. It starts to become less about fitness and more about how willing you are to keep moving even when you are so uncomfortable. I remember locking onto the stride of the runner in front of me and simply trying to hold on. I stopped thinking about pace and started thinking only about survival. My body hurt and I wanted to quit, but I had incredible people supporting me throughout that race, cheering me on every step of the way. Somewhere during those final kilometers, I learned something about myself. I learned the strength of my own mind. I kept repeating one sentence, “I can do hard things.” And that became my mantra.
The marathon taught me that endurance is not just physical fitness. It’s resilience. It’s grit. It’s choosing to keep moving forward when everything in you wants to stop. It wasn’t the prettiest race, but it became one of my most meaningful. While I missed my sub-4-hour goal, I can look back now and appreciate the result for what it is. I had set out with a very aggressive goal for my first marathon.
Final time:
4 hours 15 minutes.
A marathon doesn’t just leave you tired. It significantly depletes your glycogen stores, breaks down muscle tissue, disrupts hydration and electrolyte balance and places huge stresses on the immune system. Recovery nutrition isn’t optional; it plays a major role in how well your body repairs and recovers afterward. One of the most important recovery windows is the first 30-60 minutes post-race and a banana just won’t cut it. Your body is most efficient at replenishing glycogen stores and beginning muscle repairs during that window.
A common guideline to aim for is roughly:
1-1.2 grams of carbs per kg of body weight combined with 20-40 grams of protein
· Carbs for replenishing energy stores
· Protein to support muscle recovery and repair
· Fluids and electrolytes to replace sweat loss
Some easy to digest foods that are often best after such an effort. Oats, recovery smoothies, chocolate milk.
In the days following a marathon continuing to eat enough carbohydrates, protein and healthy fats as well as micronutrient rich foods become incredibly important for restoring energy, reducing soreness and supporting overall recovery. Recovery is the final part of the race.
Looking back, I am so proud of that race. Not because it was perfect, but because I learned so much from it. It changed everything and made me fall even more in love with running. It was that moment I stopped viewing nutrition as optional and started seeing it as a fundamental part of performance and recovery. If I wanted to improve as a runner, I knew it had to start there.
If you are currently training for a marathon or a big race of any kind, I encourage you to spend as much time practicing your fueling strategy as you do your pacing and workouts. Your body will thank you for it.
Fueling is not an extra part of training. It is part of the training.
If you want to learn more, check out this article: Runnersworld
Fuel Your Adventure