The sports nutrition industry would love to fuel your entire 100km on gels and bars. They are easy to carry, reliable in calories, and heavily marketed at runners. They are also one of the most common reasons people fail to finish long ultras.
After fourteen years of racing ultras — Badwater 135 in Death Valley, Ultra Gobi 400km across the Gobi Desert, the Authentic Phidippides Run 500km from Athens to Sparta and back — I have a straightforward view on nutrition for long events. Simple food, eaten on a schedule, before you feel like you need it. Everything else is details.
Here is what actually works.
Hunger and thirst signals arrive with a delay of 20 to 30 minutes during sustained exercise. By the time you feel hungry at kilometer 55, you needed to eat at kilometer 40.
This is the single most important nutrition principle in ultra running, and it is the one most consistently ignored by first-timers. They eat when they feel hungry. They drink when they feel thirsty. And then they wonder why they bonk at kilometer 65 despite feeling fine at kilometer 50.
The rule: eat and drink on a schedule. Something small every 45 to 60 minutes, regardless of appetite. Drink at every support stop, even when you do not feel thirsty.
This sounds simple. It is surprisingly difficult to do consistently over twelve or more hours when your appetite is suppressed by exertion, your stomach is under stress, and your attention is focused on just keeping moving.
Practice it on long training runs before race day.
Gels work well in the first half of a long ultra. They are easy to take while moving, digest quickly, and deliver reliable energy. The problem is what happens after 6 to 8 hours of continuous effort.
Your digestive system, under sustained physical stress, starts to revolt. The concentrated sugars and artificial flavorings that were fine at kilometer 30 become genuinely nauseating at kilometer 70. Many runners find they simply cannot face another gel after a certain point — and forcing yourself to eat something your body is rejecting creates its own problems.
What works in the second half of a 100km looks nothing like a gel.
Warm soup at night is worth more than any gel at that stage, both physically and psychologically. Something warm, salty, and familiar — when you are cold, tired, and have been moving for 10 hours — has an effect that goes far beyond its caloric value.
Cola and other fizzy drinks help with nausea and provide quick sugar. This is not sports science mythology — it works consistently across many different runners and conditions.
Rice balls, bread, boiled potatoes, bananas, biscuits — simple, familiar foods that you will actually eat are always better than optimally formulated food you cannot face. Your body at kilometer 75 does not need the perfect macronutrient ratio. It needs calories it will accept.
The rule: plan your support car food around what you want to eat when exhausted, not what the nutrition labels say is optimal.
You will sweat significantly over a 100km. You need to replace sodium, not just water.
Drinking large amounts of plain water without replacing sodium causes hyponatremia — a condition where sodium levels in the blood drop dangerously low. Symptoms include nausea, headache, confusion, and in serious cases, much worse. It is entirely preventable and surprisingly common in long events where runners drink aggressively but do not eat salt.
Electrolyte tablets, salty food, miso soup, soup with stock — all serve this purpose. If your urine is very clear, you may be over-hydrating without replacing salt. Light yellow is the target.
On the Yanbaru route in Okinawa, the weather in winter is mild — 15 to 22 degrees — so sweat rate is lower than in hot conditions. But salt replacement remains important over a 12 to 17 hour effort.
If you are running a supported 100km, your food rides in a support car that meets you every 20km or more often if needed. This means you can carry more variety than in an unsupported race.
Here is a practical starting list for the support car:
Savoury: - Cup noodles or instant miso soup (hot water from a thermos) - Rice balls (onigiri) — simple, familiar, easy to eat while moving - Boiled potatoes with salt - Crackers or plain bread - Small portions of whatever warm food you know you like
Sweet: - Bananas - Dates or dried fruit - Biscuits or rice crackers - Small chocolates
Drinks: - Cola (not diet) — for the second half - Electrolyte drink - Plain water - Something warm — tea, soup, warm sports drink
Gels and bars: - Yes, bring them — they are useful in the first half and as emergency calories later - But plan your support car food as if gels are a backup, not the main strategy
Important note for Okinawa: Specialist sports nutrition products are hard to find in rural northern Okinawa. If you rely on specific gels, bars, or electrolyte products, bring them from home.
There will be periods during a 100km when the idea of eating anything is genuinely unappealing. Your stomach is unhappy, you feel slightly nauseous, and the thought of putting food in your mouth seems wrong.
Eat anyway. Something small. A few crackers. A banana. A few sips of soup.
The nausea at kilometer 68 is almost always at least partly caused by low blood sugar — which eating will fix. The problem feeds itself: you feel sick, so you don't eat, so your blood sugar drops further, so you feel sicker. Breaking that cycle with a small amount of food, even when it seems counterintuitive, is one of the highest-value interventions in a difficult ultra.
Give it 20 minutes after eating before you assess how you feel.
The Yanbaru 100k guided ultra runs November through March on the coastal roads of northern Okinawa — from Ogimi Village north to Cape Hedo and back. I run alongside you for every kilometer, and we plan your support car food together in detail before Day 2.
The route is semi-supported: a car meets you every 20km with water, and your food rides in that car. Simple, practical, and allows you to run with exactly what your body needs rather than whatever fits in a vest pocket.
Details at yanbaru100k.okinawaultra.run.
Michal Činčiala is a Czech ultra runner and coach based on Hamahiga Island, Okinawa during the camp season. Key races: Badwater 135, Ultra Gobi 400km (10th overall), Ultra Milano-Sanremo 285km (3rd overall), Spartathlon, MOAB 240, Authentic Phidippides Run 500km. He coaches marathon runners through their first 100km ultra on the roads of northern Okinawa.
Running your first 100km in Okinawa — guided, coached, semi-supported on the Yanbaru coast.
Learn about the Yanbaru 100k →