So, you’ve logged the miles, hammered out those back-to-backs, and dragged yourself through some gnarly trail runs. Now race day’s breathing down your neck. And here’s the truth: if your nutrition, hydration, or gear setup is off, it doesn’t matter how fit you are—you’ll suffer.
A 50K isn’t just about running. It’s about managing your energy, keeping your gut happy, and staying comfortable hour after hour.
Let’s break it down runner-to-runner—what to eat, how to hydrate, and what gear you better not mess up.
Fueling for the Long Haul
You’ve probably heard the joke: “Ultras are just eating contests with some running in between.” It’s funny because it’s painfully accurate.
In a half marathon, maybe you can get away with a couple of gels and some water. But for a 50K? Nope. If you show up with just a gel or two in your shorts pocket, you’re setting yourself up for a bonk-fest.
You need a fueling plan—and you need to practice it in training.
Why You Need to Eat
Once you’re running longer than two hours, your body starts running low on stored carbs (aka glycogen). Keep pushing without refueling, and your legs are gonna quit on you.
In a 50K, you’re likely out there for 5 to 8 hours—or more—so skipping calories isn’t an option.
How Much to Eat
The general rule: shoot for 30–60 grams of carbs per hour. That’s about 120–240 calories per hour.
If your stomach can handle it, some athletes even push closer to 90g/hour (360 calories), but you’ve gotta train your gut for that.
When I first started ultra training, I could barely stomach 30g/hour—one gel and maybe a few sips of sports drink. I worked my way up by testing different combos: gels, chews, sports drinks, bananas, mini sandwiches… some of my long runs felt more like a buffet than a workout.
Practice Eating Like It’s Race Day
Here’s the golden rule: nothing new on race day.
Use your training runs to test what sits well—and what sends you sprinting for the bushes. I learned that after four hours, I couldn’t stomach anything sweet. Gels started tasting like syrupy glue.
Luckily, I had practiced with salty stuff: peanut butter pretzels, tiny boiled potatoes, even cheese crackers. That variety saved my stomach—and my race.
And it’s not just me. Research backs this up: studies show that as runners go longer, they often lose the desire for sweet foods and crave salt or umami instead. Trust your tastebuds—they’ll start yelling when it’s time to switch things up.
Real Food vs. Sports Fuel
Most ultra runners use a mix of sports fuel (gels, chews, sports drinks) and real food. Some stick to the basics. Others treat aid stations like diners.
I still remember grabbing a quarter of a grilled cheese at mile 20 of a trail race—it was greasy, warm, and absolutely perfect. Gave me energy and a much-needed morale boost.
There’s no universal fuel that works for everyone. Some folks swear by pickle juice and broth; others can’t race without PB&J bites.
Whatever you choose, just make sure you’re hitting your calorie goals and testing it in training.
Eat Early, Eat Often
One study on ultramarathon nutrition found that finishers were consistently hitting 250+ calories per hour, while those who DNF’d were only managing under 200.
That stat hit home. Now, I set a timer on my watch to nudge me every 30–40 minutes: “Eat something—even if you’re not hungry yet.” Because once you feel like you need food, you’re already behind.
💬 What about you? What’s your go-to trail snack? Drop it in the comments—I might steal it.
Stay on Top of Hydration
Food matters, but so does water. And if you mess this up, you won’t just feel tired—you could cramp, overheat, or worse. Dehydration is brutal.
How Much to Drink
The usual range is about 500–750 ml of fluids per hour (around 2–3 cups), depending on the weather and how much you sweat. But it’s not one-size-fits-all. Your thirst cues, the humidity, and your sweat rate all play a part.
You might’ve heard “drink to thirst.” That advice is now pretty common, and it works well—for some. In fact, experts now agree that for many runners, letting your body guide you is enough to stay properly hydrated.
But… that doesn’t always apply during ultras.
When you’re tired or cold, thirst cues can shut off. Coach Jason Koop has warned about this—he says you can’t just trust thirst, especially when running at altitude or in extreme conditions.
His advice? Figure out your sweat rate during training and aim to replace about 90% of what you lose.
What I Do
Personally, I drink every time I fuel. It keeps things simple: gel + a few sips.
And if it’s hot or dusty like that desert stretch I ran in Bromo? I up the intake. I was easily downing 600–700ml/hour on that course just to keep up.
In the mountains, with cooler temps, I might drink half that. But I always make sure I’m sipping regularly.
Don’t Skip the Electrolytes
Here’s where some runners mess up.
If you sweat buckets and only drink water, you risk flushing out your sodium levels. That can lead to something dangerous called hyponatremia. Not fun.
So include electrolytes—whether through sports drinks, drink tabs, or salty snacks.
I personally don’t use salt pills. Instead, I mix electrolyte tabs into my bottles and eat things like pretzels or crackers. That combo has kept me balanced on the trails.
💡 Pro tip: Finish your long runs at the same weight you started, give or take a pound. That’s a sign you stayed pretty well hydrated. If you’re way down, you didn’t drink enough. If you’re heavier, you might’ve overdone it.
Race Day Nutrition: Fueling for the Long Haul
Look, running 50K isn’t just about strong legs — it’s about fueling smart.
You’re out there for hours, and if you don’t eat and drink right, your engine’s going to sputter.
This isn’t the time to wing it. If you’ve trained for this, you’ve already tested what works.
Now it’s go time.
Pre-Race Fueling: The Night Before & Morning Of
The night before the race is not the time for culinary experiments. Think simple, carb-heavy, and easy on your stomach.
I still remember my first 50K — I downed a bowl of pasta, a bit of grilled chicken, and kept it bland on purpose. I wasn’t trying to win MasterChef — I just wanted fuel that wouldn’t fight me mid-race.
The science backs it up too: carbs fill your muscles with glycogen — your body’s main fuel for long-distance stuff. According to research by Johns Hopkins Medicine, topping off your carb stores 1–3 days out helps you last longer and push harder.
Morning of?
Keep it light and 2–3 hours before the gun goes off. Here’s what’s worked for me and my runners:
- Oatmeal + banana + drizzle of honey — solid carbs, goes down easy
- Peanut butter toast — fat and carbs combo that sits well if you’re used to it
- Banana-spinach smoothie with a scoop of protein — if you’re not big on solid food early
Skip the greasy stuff and high fiber unless you enjoy port-a-potty detours.
Coach’s Tip: Practice this in training. Race day isn’t the time to “try something new and exciting.”
Hydration: Sweat Smarter, Not Just Harder
Dehydration will wreck your race faster than any hill.
During one hot ultra, I skipped a couple sips early on and ended up cramping like crazy by mile 20. Lesson learned: drink before you’re thirsty.
Shoot for 500–750 ml of fluids per hour — more if it’s hot or you sweat like crazy. That’s 2–3 cups every hour.
But don’t just guzzle — sip as you go.
And plain water? Not enough.
You lose sodium, potassium, magnesium — all the good stuff.
I always pack electrolyte tablets or powder in my vest. Most aid stations offer them, but I trust my own mix.
During the Bromo Desert 50K, I made sure to sip electrolytes every 30 minutes. It saved me when the sun started cooking us alive.
Tip: Set a hydration alarm on your watch. Or use your fueling breaks as your drink cue.
Fueling During the Race: Feed the Fire
Once the gun goes off, the clock starts ticking on your glycogen stores.
Don’t wait until you feel drained — it’s already too late.
I eat something every 30 to 45 minutes. That’s usually 30–60 grams of carbs per hour. A gel here, some banana there, maybe a salty snack if I’m feeling off.
Here’s my go-to stash for a 50K:
- Energy gels — easy, quick sugar. I use these early when my stomach’s still happy
- Bananas — carbs + potassium. Nature’s endurance snack
- Pretzels — salty, crunchy, and they keep my gut happy
- Chews or bars — good for when I need something to chew on
Note: Don’t overdo it.
I’ve coached runners who hit every aid station like a buffet. Their stomachs shut down halfway in.
Find your rhythm and test your race-day menu in long runs.
I even keep a timer on my watch to buzz every 40 minutes — not because I forget to eat, but because in the middle of a race, everything becomes a blur.
Real Talk: You Can’t Fake Fueling
Running a 50K takes more than guts. It takes a plan—and your fueling is part of that plan.
You can train hard for months, but if you mess up your nutrition, your legs won’t save you.
So, practice it. Refine it. Stick to what works.