How Much Carbohydrate Do You Actually Need During an Ultra?

One of the most common questions we hear from ultrarunners is: How much should I actually be eating during a race?

Sounds simple… but it’s one that catches a lot of people out.

Too little, and you’re running on fumes. Too much, too soon, and your stomach starts throwing its toys out the pram.

Fuelling right can be the difference between running strong, just surviving… or calling it a day early. The goal? Finding what works for you.

Why Carbohydrate Matters in an Ultra

During long efforts, your body uses a mix of fat and carbohydrate for fuel.

But carbs are the premium stuff. They’re what help you:

• Hold a steady pace

• Push climbs

• Stay sharp and make good decisions

The catch? Your internal stores are limited. Without topping them up, performance will gradually drop off.  Carbohydrates also help maintain blood glucose levels, which naturally dip over long durations.

So… How Much Do You Actually Need?

For long-distance endurance events, the general recommendation is 60–90g of carbohydrate per hour.

You might have seen elite runners pushing 120g+ per hour (wild, we know), but for most ultrarunners (especially if you’re newer to the distance) that 60–90g range is a solid target.

And importantly, you don’t need to jump straight to the top end.

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Start With What You Can Tolerate

If this is your first (or second) ultra, a good place to start is at 40–60g per hour. That could look like:

• 1 gel every 20–30 minutes

• A bottle of carb drink per hour

• A mix of both

• Small amounts of real food alongside sports nutrition

(It’s worth checking labels too,  some gels have 20g of carbs, others pack in 45g.)

From there, you can build things up in training. A simple progression might look like:

• Start: 40–50g/h (find what sits well)

• Build: 50–70g/h (keep an eye on how you feel)

• Advanced (if trained): 70–90g/h+ (trickier to manage, both logistically and taste-wise)

More Isn’t Always Better

It’s tempting to think: if carbs help performance… more must be better, right? Not quite.

Taking in more than your gut can handle is one of the fastest ways to derail your race:

• Nausea

• Bloating

• Cramping

• Reduced intake overall

• Dehydration (when fluids become hard to stomach)

• Time lost at aid stations

• Or stopping altogether

The aim isn’t to max out your intake, it’s to find the highest amount you can comfortably tolerate.

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Simple Ways to Get It Right

Practise in training
Use your long runs to test your fuelling.

Be consistent
Little and often (every 15–30 mins) beats big, occasional hits.

Mix it up
Drinks, gels, real food. Variety helps avoid flavour fatigue.

Adjust as you go
Your pace, appetite, and conditions will change. Your fuelling can too.

The Takeaways

1. There’s no single “correct” number. You don’t need to follow an elite runner’s plan or hit some perfect target. You need something practical and repeatable.

2. Dial it in during training, refine it over time… and by race day, you’ll know exactly what works for you.

3. Get this right, and you give yourself the best shot at running strong, not just at the start, but all the way to the finish.

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Special thanks to Jamie Pugh for his contribution to this article.

Dr Jamie Pugh is an applied sport and exercise physiologist and performance nutrition specialist. His academic training includes a PhD focused on applied aspects of sports nutrition and metabolism, and he has worked with elite and international endurance athletes within athletics, ultramarathon running, and professional cycling.