How to Fuel Ultras & Long Runs: Ultramarathon Fuelling Strategy

How to fuel during ultras and long runs

Introduction

Fuelling long runs and ultramarathons is one of the most misunderstood parts of endurance training. Many runners under‑fuel, fuel too late, or rely on foods their gut simply can’t handle. The good news is that you don’t need a complicated spreadsheet or expensive products — you just need a clear, practical system as part of your ultra marathon fuelling strategy that you can test in training and trust on race day.

This guide breaks down a simple, science‑backed fuelling strategy designed for long runs and ultras of any distance.

Why Fuelling Matters

• Limited carbohydrate stores

• Risk of hitting the wall

• Effort spikes when under‑fuelled

• Additional ultra‑specific challenges: flavour fatigue, gut tolerance, heat, altitude, aid station spacing, and long durations

Fuelling well keeps your effort stable, your energy consistent, and your long runs enjoyable.

1. Know Your Numbers

Calories

• Start with ~250 calories per hour

• Adjust based on body size, intensity, and conditions

Carbohydrates

• Up to 3 hours: 30–60g/hr

• 3+ hours: aim for 90g/hr

• Use a 2:1 glucose–fructose blend to maximise absorption and reduce GI issues

Protein

• ~0.25g/kg/hr for long ultras

Fat

• Use as tolerated — helpful for satiety and variety, but slower to digest

2. Choose the Right Fuel for the Right Distance

Shorter Long Runs (up to ~3 hours)

Quick, easy carbs work perfectly:

• Gels

• Chews

• Carb drink mix

• Simple sweets

  

  Protein Rebel Maple Gels

  
  

Longer Runs & Ultras

You’ll want more substantial foods:

• Potatoes

• Pretzels

• Wraps

• Broth

• Rice balls

• Bars

  
  

Gels in Training

• Important for gut training

• Helps you learn which brands/flavours work

• But expensive — mix with real food on easier days

Carb Drinks

• Fuel + hydration in one

• Easy to sip regularly

• Great for hot races or when chewing is hard

  
  

3. Build Your Food Tiers

A simple system to avoid flavour fatigue and GI surprises.

Tier One — Go‑To Foods

Your favourites: sweet, salty, savoury, engineered fuel + real food.

Tier Two — Backup Options

Foods you tolerate but don’t want all day.

Tier Three — Safe Unknowns

Similar to Tier Two — useful at aid stations.

Off‑Limits Foods

Anything you dislike or know upsets your stomach.

4. Train Your Gut

Your stomach adapts just like your legs.

Practice:

• Eating on the move

• Eating in heat, cold, altitude

• Eating different textures

• Drinking while running

• Eating at aid‑station effort

Race day should never be the first time you try something.

Race‑Day Ultramarathon Fuelling Strategy

Before the Race

• Increase carbs slightly

• Reduce fats and proteins

• Lay out your food tiers

• Check aid station spacing

  
  

During the Race

• Start fuelling early (30–40 minutes)

• Aim for 250 calories/hr

• Hit your carb targets

• Use your tiers to avoid flavour fatigue

• Adjust for heat or cold

  
  

After the Race

• Keep moving briefly

• Get warm

• Eat something small and familiar

  
  

Final Thoughts

Fuelling long runs and ultras isn’t about perfection — it’s about planning, practicing, and adapting. With a clear system and consistent gut training, you can fuel confidently no matter the terrain or duration.