How you fuel is a key success factor to finish your first marathon. For first-timers, it can be overlooked and make it more difficult than needed. Today, I’ll share how I plan carbs and fluids from long run to race day, and what Kyoto Marathon 2026 added to my notes.
Your body needs energy to sustain marathon effort. For long work at race intensity, carbohydrate carries most of the load, glycogen in muscle and liver, topped up by what you swallow on the move. Fat contributes, but carbs are what you can absorb and redeploy in repeated small hits; they are the usual backbone of marathon fuel.
Fluid runs alongside that. Water supports blood volume and sweat. Electrolytes (sodium first among them at typical road-marathon aid stations) replace what you lose in sweat and help nerves and muscles behave predictably.
Together, water and electrolytes support how muscles and nerves function under stress; they are not a cramp cure, but starting dehydrated or salt-depleted is a self-inflicted mistake you can plan away (cramping still has other causes, including fatigue).
What follows is how I put fuel and fluid into practice: rehearse on long runs, tighten the clock on race day, stay boring on course food when the tables look tempting. The first section is about why mistakes surface late, including a Kyoto example where fuel and fluid were fine, but heat forced a pace trade.
Why fueling errors show up late (race-day reality) #
A half marathon rarely teaches what the full distance does to glycogen stores and how much pace you can hold when reserves run low. The first half of the race can feel almost easy; but the demand still accumulates.
If the carb intake does not keep pace with what you burn at your target pace, the second half gets expensive metabolically. This is what people call that “the wall.” Often it is slower: output and substrate slowly drift apart.
Low glycogen often shows up as the same pace feeling harder, foggy thinking, or rhythm falling apart. Dehydration or a rough electrolyte balance can feel similar: dizziness, stomach trouble, or a washed-out, wrong feeling. The fix is not always “more gels.” I try to leave no obvious gap in fuel (carbs) or fluid (water plus electrolytes) and let the race show which limit mattered.
My recent Kyoto Marathon is my counterexample to the idea that a correct bottle-and-gel plan immunises you against every late-race limiter; that day, heat trumped everything else. I hit water and electrolytes every three to five kilometres, gels on the schedule I trust, and still from about 32 km I could not get cool enough.
Drinking was not the missing step; my body was not shedding heat the way I needed.
I eased pace from roughly 4:55min/km to about 6:00min/km over the last five kilometres. No personal best on the line; finishing controlled beat holding a pace my system would not service.
Fuel and fluid were in place; the day still asked for something else first. I had already spent years chipping away at running in heat and humidity; Kyoto was the marathon where that limiter spoke louder than the gel schedule.
The belief landscape (mistakes before the first gel) #
Breakfast is real work. It tops up liver glycogen and settles the stomach. It is not the same as feeding three or four hours of marathon effort on the move.
Plenty of first-timers eat well the night before, then treat breakfast as optional, and feel fine until they do not.
When fueling is not tied to pace and expected duration, early gels are easy to skip, because breathing still feels fine. That is the expensive one. Glycogen does not fully “catch up” if you try to slam it in late.
My long-run mornings stay boring on purpose: something easy about 30 minutes out (banana, bread with honey), plus electrolytes beforehand. That is not advice for everyone; it is what I have actually run on. Some people need more time to feel ready.
Carbohydrate need and practicing intake #
You will see plenty of books referring to the same band: ~30–60 g/h for marathon-length work. Higher targets exist, but they usually assume trained guts and specific carb mixes, not something to invent on race week.
Pace, gut tolerance, and how hard you are already working shrink that window in practice. I read the numbers as a compass, not a contract.
Smaller, repeated doses beat one giant hit for me: less gut shock, steadier glucose across hours. A hard pace leaves little room for GI mistakes; the plan that matters is the one you can run without breaking cadence.
Gut training, for me, is the same breakfast family, the same gel spacing, the same drink strength on long runs, including hard long runs, not only easy days. I rehearse the boring stuff: walk an aid station or not, gel while moving or not, where backup lives if the table is a scrum.
In my training block, from 18 km upward, I carry gels and take one about every 6–8 km, pace and feel nudging that.
On marathon day, I switch to the clock: about every 30–35 minutes, with kilometre marks as a backup. If nausea or sweetness stacks early, I mentally allow half a banana or course sweets only if I have tried them before. I only carry gels; anything else is whatever the race gives and whatever I already trust.
I have tried a lot of brands over the years, but Pure Sport Nutrition gels are still my favorite to this day.
On race morning, I mix one concentrated carb–electrolyte drink (about 90 g carbs in the bottle), then dilute or chase it with extra water so I start topped up without living in the porta-potty. That ratio took a few long-run dress rehearsals to get right. I would not try it race morning untested.
Kyoto was a travel reminder: bananas and familiar brands often exist abroad if you scout a day or two early. I still could not always finish gels on schedule once late-race effort and discomfort stacked.
Strawberries on the course felt like a gift: low risk, mentally welcome. I did not treat the marathon as a place to try whatever looked interesting. Wrong day for that experiment.
Fluids and electrolytes #
Thirst arrives late and tells partial stories. It is easy to confuse a busy aid station, a sloshing stomach, or a few cups with “sorted,” and still run short on fluid for the hour. Sweat rate swings by person and day; copying the runner next to you is a guess.
Tables every few kilometres create their own failure modes: too little early, then panic late, or big gulps in a short window and a complaining stomach. I decide the pattern ahead: small sips often, electrolyte where I already know it sits well.
Sodium and cramps: some people cramp with low losses; plenty of crampers are hydrated. I keep electrolyte drinks in the “reasonable insurance in long racing” bucket, not “this stops cramps.”
On chilly mornings like those in Seoul or Hobart (Tasmania) for me, I still drink hot tea before the start. Habit and comfort before the electrolyte bottle, not a prescription for everyone.
Execution errors on the course #
Skipping fuel early because you still feel comfortable is a high-risk gamble (see above on early gels and breakfast). Trying to “make up” with extra gels late usually meets a gut that will not take volume or sweetness anymore.
On race week, do what you know: no new breakfast, no surprise gel, no expo free sample. If it never showed up in training, it was never in the plan.
Closing: minimal plan, checklist, and what to iterate next #
I start swallowing before hunger or a late-race fade shows up. Mood is a liar on a marathon clock. I tie carb intake to time or distance, widen fluid sips when sweat is heavy or stations are close, and sometimes thin or slow carbs if the stomach revolts.
Before I travel to a start line I run a quick inventory in my head: breakfast and gel brands rehearsed on long runs, backup on my body not only in a bag, station spacing from the map and a rough sense of minutes between tables if spacing is uneven. I keep the wider race-day logistics and gear picture like travel, documents, and kit in the same calm head space with StartLine.
Afterward I compare races: gel completion rate, drink pattern, any GI noise. If pace targets climb, fuel and fluid rehearsal has to creep toward real effort. Nobody gets one formula forever; the first marathon is mostly about not improvising the basics. The second is where the details get personal.
In short: late pain is usually stacked: fuel (glycogen), fluid and electrolytes, and pacing, not one clean cause.
Breakfast opens the door; hourly carb rhythm walks through it. Rehearse brands and schedules; change when taste or gut pushes back. Fluids follow the map and your preset pattern more than thirst alone. On the course, skip expo experiments and late cramming; hold to the clock, adjust when logistics or your stomach push back. Kyoto was the year I ran my fuel and fluid plan as written and still traded pace for control. When the system overheats, nutrition alone cannot buy back what physiology will not give.
There is no affiliate relationship with Pure Sport Nutrition.
- Photo by Markus Winkler