Getting ready to chase an FKT up high? Here’s everything I learned about fueling at altitude — from the science behind why your body rebels above 15k feet to the exact snacks I packed for summit day. Because you can’t run to 19,431 feet on vibes alone.
The Route
Kilimanjaro’s Northern Circuit is no shakeout run. It’s 53-60 miles long, crosses five ecological zones—from tropical rainforest to alpine desert—and tops out at Uhuru Peak: 19,431 feet. It’s remote, wild and never used for speed attempts, which is precisely why I chose it.
This FKT attempt is personal. It’s rooted in a question I’ve been chasing for a long time:
What happens when you go all-in on something that scares you?
That question led me to Kilimanjaro. It’s where big fear meets big effort. And I’m using that effort to fuel something bigger.
This attempt is also a fundraiser through The Cairn Project, supporting the Summit Scholarship Foundation, an initiative that provides scholarships and outdoor experiences for women and girls. Access to wild spaces shouldn’t depend on privilege or proximity. Confidence, grit and self-trust aren’t built in a vacuum. They’re built through effort, movement and the chance to go after the big things that call to you.
The Fueling Conundrum
You can’t run up Kilimanjaro on vibes alone. For this FKT attempt, fueling is one of the most strategic (and honestly underrated) parts of my plan. Thin air, suppressed appetite and a body working overtime don’t exactly make eating easy or fun.
I’ve done the reading, tested the snacks and practiced at altitude. My game plan combines science, mountain-tested advice and a healthy dose of trial and error (plus snacks that don’t make me gag at 15,000+ feet).
Here’s what I’ve learned and how I’m fueling: on recon, on the push and everything in between.
Altitude Doesn’t Play Fair
The higher I go, the harder everything gets, especially nutrition. I’m not being dramatic here. Above 15,000 feet, my body starts rewriting its own rules, and what used to work on my local trail run suddenly doesn’t even make sense.
Appetite goes MIA
One of the first things to disappear at altitude? My desire to eat. Altitude suppresses appetite and can stir up a nice side of low-grade nausea.¹ That means even my favorite snacks can suddenly feel like a chore.
And when I say “not hungry,” I mean actively repulsed by food, which is a problem when my body is begging for fuel. So no, I’m not relying on hunger cues. I’m setting alarms and going full toddler-mode with bite-sized snacks at regular intervals, whether I feel like it or not.
I Burn More Than I Think
Even when I’m standing still, my body’s working overtime. Basal metabolic rate increases, heart rate ticks higher and my body starts burning through fuel more rapidly just to keep me warm and functioning.²
At high altitudes, my body shifts into carb-craving mode because carbohydrates are the most efficient fuel source when oxygen is limited.³
So carbs become non-negotiable. This isn’t a keto-friendly mountain. This is a “sugar me up and keep me moving” situation. Gels, chews, broth, rice—whatever gets the job done.
I Dry Out Quickly
You know that dry-mountain-mouth feeling? Multiply it by ten. At altitude, every breath pulls more water out, and the cold, dry air doesn’t help. Add in increased urination (thanks, acclimatization) and you’ve got a recipe for stealth dehydration.⁴
The worst part? I won’t feel thirsty. My thirst cues are about as trustworthy as my GPS signal on the crater rim.⁵ That’s why I’ll be sipping constantly—timed, measured, deliberate—and counting on electrolytes to help the water stick.
Before the Climb
This isn’t the time for calorie restriction, trendy diets, or pretending I don’t need a second breakfast. (Shoutout to Tolkien and the Hobbits for normalizing the best meal of the day.) I’ve been eating like I mean it, fueling training runs, big climbs and the recovery windows in between.
I fueled hard during peak training with vegan pizza, loaded burritos and second servings. I focused on iron-rich meals, including lentils, spinach, tofu, and, for the omnivores among us, some red meat. And I’ll do the same here. Iron is key to oxygen-carrying capacity at altitude.⁶
Hydration targets: at least 3 liters daily, every day in the weeks leading up to departure – always with electrolytes. Colorful, whole-food meals to boost antioxidants and immune function.⁷ (Also: they just taste better.)
I’ll be eating for what my body needs for 10+ hours into a summit push, above 15,000+ feet, with my heart rate racing and my stomach on edge.
Base Camp + Acclimatization
I’ll spend three nights at a tented camp just outside the park boundary, sorting gear, recovering from travel and coaxing my body into mountain mode. African Environments is setting the stage, and fortunately, they have a camp cook who takes fueling as seriously as I do.
I’ll eat high-carb, moderate-protein meals to support glycogen storage and muscle repair. I’ll snack frequently, because appetite isn’t guaranteed at 15k+ feet. And I’ll keep water bottles + electrolyte tabs within arm’s reach at all times.
The plan is to hike to 8K–9K feet for acclimatization (and a little test run for the fueling plan).
Basically: fuel, move, hydrate, repeat.
Reconnaissance
The recon is a four-day, five-night trip on the mountain. I’ll hike and run the whole route, crossing all the terrain I’ll face on the attempt—from rainforest to alpine—and drop fuel and gear at two checkpoints along the way.
The goal is simple: set myself up for success. Know the route. Test my systems. Show up to the FKT attempt with as few surprises as possible.
What I’m bringing:
PILLAR Performance Triple Magnesium – recovery support every night
Gnarly Vegan Golden Milk Protein – in breakfast oats or a shake at lunch
3-5 liters of water/day, with electrolyte mixes (and yes, hydration timers)
Something to eat every 30 minutes: chews, bars, trail snacks, and the occasional weird combo that just works at 15k+
Summit Push: FKT Day Fueling
This is the main event.
I’ll start in the dark—predawn, likely around 3 AM—headlamps on, nerves firing, legs buzzing. Temps in the 70s at the base, dropping to the 20s (or below) as we near 19,000 feet. Not to mention whatever the famous Kilimanjaro wind decides to throw at me.
It’s going to be a long 24–36 hours with very little room for fueling mistakes.
What’s in my pack:
Carb Fuel gels: caffeinated, salted, regular, SiS Beta Fuel + Isotonic Gels (they go down smoother when breathing gets rough)
Precision Fuel and Hydration: PF 30 Chew, and their drinks (in two flasks) + plain water (in a hydration bladder)
I’ve got two checkpoints along the route to reload.
Checkpoint 1: Mile 21 – right before the push to Uhuru Peak. I’ll grab fuel, swap gear and get ready for the steepest and coldest climb. If something’s going to go wrong, it’s probably going to happen after this checkpoint.
Checkpoint 2: Mile 37 – post-summit, after the big descent. I’ll be wrecked, but still need to eat, adjust layers and keep moving. From there, I drop back into the tropical zone for the final miles.
These won’t be leisurely breaks. They’ll be short, intentional stops: fuel, refill, reset, go.
Checkpoint fuel stash:
Coffee Broth + Gnarly Golden Milk Protein (likely once we descend to 15k)
PILLAR magnesium (pre- and post-summit)
Chips, cookies, sandwiches, because sometimes real food is the only thing your brain and stomach can agree on
More gels. More chews. More sodium. More sugar.
Eat the Damn Food Anyway
Fueling at high altitude—or during any all-day (and all-night) effort—is rarely clean, cute or convenient. You can have the best plan, the right gear, every spreadsheet dialed… and your stomach might still go rogue at 17k+ feet.
That’s why I trained for it. The practice runs with a sloshy gut. The long climbs when the only thing that sounded good was a nap in the dirt.
I’ve trained my guts like I’ve trained my legs. But let’s be real, something will still go sideways. I might puke or swear off Skratch chews forever. And there will be at least one (okay, probably five) moments when I dig out a bar, gel or chew and think: absolutely not, you sticky little monster.
And I’ll eat the damn food anyway – and keep going.
When I finally get down, legs trashed, faces salt-crusted, bodies humming from effort, I’ll celebrate with whatever I can keep down. Fries? Potato chips? Finally, that nap in the dirt? TBD.
Champagne? Only after the pee test says I’m rehydrated.
Follow along:
https://www.instagram.com/m_cmacdonald/
https://www.instagram.com/binthewoods/
Sources
Meehan, R. T., et al. “The influence of high altitude on appetite and food intake.” International Journal of Sports Medicine, 1988.
Butterfield, G. E., et al. “Energy metabolism at high altitude.” Nutrition Reviews, 1992.
Gore, C. J., et al. “Altitude training and carbohydrate metabolism.” International Journal of Sport Nutrition and Exercise Metabolism, 2001.
Sawka, M. N., et al. “Physiological consequences of hydration.” Journal of the American College of Nutrition, 2005.
Beidleman, B. A., et al. “Thirst and hydration at high altitude.” Wilderness & Environmental Medicine, 2003.
Friedmann, B., et al. “Effects of iron supplementation on total body hemoglobin during endurance training at moderate altitude.” International Journal of Sports Medicine, 1999.
Nieman, D. C., et al. “Nutrition and immune function in endurance sports.” Current Sports Medicine Reports, 2002.
