100-Miler Experience Notes – Part 2: Fuel Calculations & Logistics
When it comes to running 100 miles, the physical training is only half the story. The other half? Fuel.
Nutrition planning for an ultra like this is both science and self-discovery. The general target is 60–90 grams of carbohydrates per hour (and according to newer studies, even up to 120 g). That’s an almost impossible number to imagine — and even harder to stomach, literally.
As I always tell my clients: you have to train your tummy. We aren’t naturally designed to digest and absorb that much fuel over nearly 28 hours of continuous movement.
Finding what works for me
I spent a year training not just my legs but my gut, experimenting with foods and electrolytes during long runs. By the time race week arrived, I knew what worked: solid food.
I need sandwiches, wraps, bars — real textures. Powders, gels, and gummies? No thanks. My body and brain both rebel.
What was on my menu
My all-time favourites made the cut:
Nakd bars
Snickers
Eat Natural bars
Maurten
Flaming Phoenix bars
Real Meal bars
Veloforte bars & chews
It was a delicious (and heavy - I mean the actual weight of it) mix of sweet, chewy, and practical.
Then came the maths. One bar averages 30 g of carbs. That means three bars an hour to reach 90 g. Multiply that by 28 hours and… you can see where this is going.
A lot of bars.
A lot of wrappers.
And a lot of £££!
Let’s be transparent: fuelling for this race alone cost a small fortune. At roughly £2.50 per bar, that’s close to £200 in snacks if I ate perfectly to plan. That realisation nudged me to do something I usually avoid: trust the checkpoint food.
Spoiler alert → It actually worked brilliantly this time.
Hydration & Electrolytes
For the first leg, I filled both 500 ml flasks with a half-and-half mix of coconut water and plain water. Coconut water is naturally rich in electrolytes and easy on my stomach.
I also carried:
High Five Tropical electrolyte tablets
MyProtein Caffeine tablets
Both are tried, tested, and trusted.
How I packed it all
This race had an interesting format: four legs, each roughly a marathon, all radiating from a central headquarters. After every loop, we returned to base to refill, change gear, and head out again.
Here’s how I organised it:
Leg 1: fully packed running vest.
Legs 2–4: each leg’s nutrition pre-packed in a labelled plastic bag. When I got back to HQ, I could just grab the next one — no thinking required.
Drop-bag extras: a few bonus bars just in case (I guess I didn’t fully trust the check-points after all ;)
That system worked beautifully and saved precious minutes (and mental energy).
When the plan meets reality
Another spoiler alert: I didn’t run for 28 hours — and I didn’t eat everything I packed - not even close! By the final hours, my stomach had had enough. I relied mainly on small bites at checkpoints and the occasional piece of solid food.
It’s one of the great challenges of ultra running: we train and plan meticulously, the stomach feels differently on race day, and yet we have to find a way to adapt and keep on fuelling our body.
Takeaway
Fueling for a 100-miler isn’t about perfection — it’s about flexibility. Train your gut, learn your preferences, and stay adaptable on race day.