Marathon Fuelling Guide: What to Eat Before & During a Marathon

Training gets you to the start line. Your marathon fuelling strategy helps get you to the finish.

Whether you're targeting London, Manchester, Brighton, Edinburgh or your first local marathon, 26.2 miles is long enough for poor fuelling, hydration or pacing decisions to undo months of preparation.

The best marathon nutrition plan isn't necessarily the one containing the most carbohydrate, gels or supplements. It's the one you have practised in training, can tolerate comfortably and can follow consistently on race day.

At Hammer Nutrition, our approach is Less is Best: consume enough fuel, fluid and electrolytes to support performance without unnecessarily overwhelming your digestive system.

This guide explains how to build a practical marathon fuelling plan the Hammer way.

Shop Marathon & Running Nutrition →

Quick Answer: How Should You Fuel a Marathon?

For most marathon runners, think about your nutrition in four stages:

Before the race: Arrive fuelled and hydrated without overeating immediately before the start.

During the race: Start fuelling early and consistently rather than waiting until you're hungry or losing energy.

Hydration & electrolytes: Drink according to conditions and your individual needs, while accounting for electrolytes lost through sweat.

After the finish: Begin replacing carbohydrate, protein, fluid and electrolytes to support recovery.

For Hammer athletes, a straightforward race-day system can be:

• Hammer Gel for portable carbohydrate energy
• HEED when you prefer energy, fluid and electrolytes in a drink
• Endurolytes for adjustable electrolyte support
• Perpetuem as an option for runners spending considerably longer on course
• Recoverite after finishing

The golden rule:

Never introduce a completely new nutrition strategy on marathon morning.

Practise it during your long runs first.

What Should You Eat Before a Marathon?

Your marathon nutrition starts well before the gun goes off.

The aim of your pre-race food is to begin with good energy availability while avoiding an unusually large, fatty, fibre-heavy or unfamiliar meal that leaves your stomach working overtime.

In the days leading into your marathon, eat familiar foods and maintain good hydration.

On race morning, choose a familiar carbohydrate-based meal that you have already tested before long runs.

Depending on your normal diet, that might include foods such as:

• Porridge
• Toast
• Banana
• Rice
• Low-fibre cereal
• Other familiar carbohydrate-rich foods

The exact quantity and timing are individual.

Race morning is not the time to copy somebody else's breakfast because it appeared on Instagram.

If your normal long-run breakfast works, don't reinvent it for race day.

For more detailed pre-race advice:

Read: What to Eat Before a Race →

Should You Carb Load Before a Marathon?

A marathon places substantial demands on your body's carbohydrate stores, so beginning the race adequately fuelled matters.

However, that doesn't mean spending the night before your race eating enormous quantities of pasta.

Your marathon nutrition should be considered across the days leading into the event, not treated as one giant last-minute meal.

Keep your food familiar, maintain carbohydrate availability and avoid turning the evening before your marathon into an eating competition.

Most importantly, don't arrive at the start feeling bloated simply because you believe more food must mean more energy.

When Should You Start Fuelling During a Marathon?

Don't wait until you feel depleted.

Once your energy levels have dropped substantially, trying to rescue your marathon becomes much more difficult.

Your race nutrition should therefore begin early and consistently.

Hammer's philosophy is not to chase the largest possible hourly carbohydrate number simply because another athlete or brand recommends it.

Your requirements depend on:

• Running pace and intensity
• Expected finishing time
• Body size
• Training status
• Weather
• What you're drinking
• What you're eating
• Your individual digestive tolerance

The goal is to provide enough energy to support your race without consuming more than your stomach can comfortably process.

How Many Energy Gels Do You Need for a Marathon?

There isn't one correct number of gels for every marathon runner.

A three-hour runner and a five-and-a-half-hour runner are performing for very different lengths of time.

Rather than asking:

“How many gels do I need for a marathon?”

A better question is:

“What complete fuelling strategy can I comfortably maintain for my expected finishing time?”

Hammer Gel is designed to provide a convenient source of carbohydrate during endurance exercise and can be carried easily in a running belt, vest or pocket.

A practical starting strategy for many Hammer athletes is to introduce fuel early and then use Hammer Gel approximately every 45–60 minutes, adjusting according to your overall intake and what you've established during training.

Remember that your sports drink also counts.

If you're consuming Hammer Gel alongside HEED or other carbohydrate-containing products, don't calculate each product in isolation.

Your stomach receives everything you consume as one combined nutrition load.

Shop Hammer Energy Gels →

For detailed Hammer Gel timing:

Read the Hammer Gel Fuelling Guide →

Should You Take Energy Gels With Water?

Your gel strategy and hydration strategy need to work together.

Hammer Gel is concentrated fuel, so water should form part of your overall plan when using it.

Don't automatically wash every gel down with large quantities of fluid, but equally don't spend hours consuming concentrated fuel while ignoring hydration.

Practise the combination during long training runs so you know what your stomach tolerates.

If conventional gels have previously caused digestive problems:

Read: Energy Gels for Sensitive Stomachs →

Hammer Gel or HEED for a Marathon?

Both can work — they simply deliver fuel differently.

Hammer Gel

Choose Hammer Gel when you prefer to drink water and take your calories separately.

Advantages include:

• Easy to carry
• Easy to monitor intake
• No simple sugars
• Multiple flavours
• Caffeinated and caffeine-free choices
• Easy to combine with water and separate electrolytes

HEED Sports Drink

HEED combines carbohydrate energy, fluid and six electrolytes in one drink.

It can suit runners who prefer drinking some of their calories rather than relying entirely on gels.

HEED is also citric-acid-free and deliberately less sweet than many conventional sports drinks.

You don't necessarily have to choose one or the other.

Some runners use HEED as their primary drink while carrying Hammer Gel for additional fuel.

Shop HEED Sports Drink →

What About Electrolytes During a Marathon?

Sweat contains more than water.

During prolonged exercise you also lose electrolytes, and the amount varies enormously between athletes and conditions.

A cool UK spring marathon is very different from running 26.2 miles on an unexpectedly hot day.

Hammer's approach is to keep fuel, hydration and electrolyte intake adjustable rather than forcing them into a fixed ratio.

The Endurolytes range allows you to modify electrolyte intake according to:

• Temperature
• Humidity
• Sweat rate
• Race duration
• Individual experience

This becomes particularly useful when race-day conditions are very different from those you experienced during training.

Shop Hammer Electrolytes →

What Should Slower Marathon Runners Eat?

Finishing time matters.

A runner completing a marathon in under three hours has very different practical nutrition requirements from somebody who will be on the course for five, six or more hours.

The longer you're exercising, the more likely flavour fatigue and appetite changes become.

Hammer Gel and HEED remain useful, but runners expecting to spend substantially longer on course may want to experiment during training with Perpetuem.

Perpetuem was developed for prolonged endurance exercise and combines complex carbohydrate with protein and a small amount of fat.

It can provide an alternative when repeatedly consuming sweet gels for many hours becomes unappealing.

Do not introduce Perpetuem for the first time during your marathon.

If you're considering it, test it on your longest training runs first.

Explore Perpetuem Long-Distance Fuel →

Should You Use Caffeine During a Marathon?

Caffeine can be useful for some athletes, but more isn't automatically better.

One advantage of Hammer Gel is that most flavours are caffeine-free, so you control when caffeine enters your race strategy.

Selected Hammer Gel flavours contain caffeine:

Espresso — 50mg caffeine per serving

Tropical — 25mg caffeine per serving

This makes it possible to use caffeine-free gels earlier and introduce a caffeinated option later if that's what you've established works during training.

Remember to count all caffeine sources, including coffee, gels, drinks and other products.

Avoid the Marathon Aid-Station Buffet

One of the easiest ways to destroy a carefully practised nutrition strategy is to start collecting unfamiliar products at every aid station.

Sports drink.

Gel.

Chews.

Banana.

Cola.

More sports drink.

Another gel.

Your stomach doesn't care that they came from different tables.

It has to process the total intake.

If you've built a Hammer race strategy during training, carry enough of your chosen nutrition wherever practical and use aid stations primarily to support your planned fluid requirements.

Don't turn race day into a nutrition experiment.

Common Marathon Fuelling Mistakes

Waiting Until You Feel Hungry

By the time you feel substantially depleted, you've already allowed your nutrition strategy to fall behind.

Fuel early and consistently.

Trying New Gels on Race Day

Your marathon is not a product-testing session.

Use your long training runs to determine which flavours, quantities and timings work.

Copying an Elite Runner's Carbohydrate Intake

Elite marathoners operate at very different speeds, intensities and finishing times.

Their strategy isn't automatically appropriate for you.

Consuming Too Many Different Products

Gel + sports drink + chews + bars + bananas + cola can become a considerable combined carbohydrate load.

Keep the strategy simple.

Drinking to a Fixed Schedule Regardless of Conditions

Fluid requirements vary with weather, pace and the athlete.

Practise hydration during training and adjust appropriately for race-day conditions.

Forgetting Electrolytes

Long-duration sweating involves both fluid and electrolyte losses.

Plan for both.

Waiting Until Race Week to Practise Nutrition

Your longest training runs are also nutrition rehearsals.

Use them.

Example Hammer Marathon Fuelling Strategy

This is an example framework rather than a prescription.

Before the Start

Eat your normal, tested pre-long-run breakfast.

Arrive appropriately hydrated.

Have your Hammer Gel, electrolytes and other planned nutrition organised and accessible.

Early Miles

Settle into pace.

Don't start consuming everything simply because you're nervous.

Begin your practised fuelling strategy early enough that you're maintaining energy rather than trying to replace it after you've depleted yourself.

Through the Middle of the Marathon

Continue your planned Hammer Gel and/or HEED intake consistently.

Use water appropriately.

Adjust Endurolytes according to your tested requirements and race conditions.

Final Third

This is where a disciplined strategy becomes valuable.

Continue fuelling even if enthusiasm for eating has disappeared.

If caffeine is part of your tested strategy, this may be where you introduce your chosen caffeinated Hammer Gel.

Avoid suddenly grabbing unfamiliar high-sugar products because you're beginning to fatigue.

Finish Line

Your nutrition strategy doesn't stop when your watch does.

Start recovery.

What Should You Eat After a Marathon?

A marathon substantially depletes carbohydrate stores and places considerable stress on muscle tissue.

Once you've finished, focus on:

• Carbohydrate
• Protein
• Fluid
• Electrolytes

Recoverite is Hammer Nutrition's dedicated post-exercise recovery drink.

It combines carbohydrate and whey protein isolate in a 3:1 carbohydrate-to-protein ratio, together with L-glutamine and electrolytes.

It's particularly convenient after a marathon when eating a large solid meal immediately may not be appealing.

Shop Recoverite Recovery Drink →

Your Marathon Nutrition Checklist

Before race morning, you should know:

• What you're eating before the start
• Which fuel you're carrying
• When you'll begin fuelling
• Approximately how frequently you'll fuel
• Where you'll obtain water
• Which electrolytes you're using
• Whether you're using caffeine
• What you'll do if conditions are hotter than expected
• What your recovery nutrition will be

If you can't answer those questions a week before your marathon, use your remaining training sessions to finalise the plan.

Frequently Asked Questions

What is the best fuel for a marathon?

There isn't one universal best product. Your ideal marathon fuel is something that provides useful energy, is practical to carry and — most importantly — has been successfully tested during your long training runs.

Hammer Gel is the standard portable Hammer option for marathon running, while HEED provides drinkable carbohydrate and electrolytes.

How often should I take an energy gel during a marathon?

Hammer athletes commonly use Hammer Gel approximately every 45–60 minutes, but your appropriate intake depends on pace, finishing time, other carbohydrate sources and individual tolerance.

Use training to establish your personal strategy.

How many gels do I need for a four-hour marathon?

Don't calculate this purely from finishing time. Determine your tested intake interval and account for carbohydrate coming from sports drinks or other foods as well.

For example, someone using a gel approximately every 45–60 minutes would plan differently depending on whether they're also drinking HEED.

Should I fuel from the beginning of a marathon?

You generally want to begin your practised nutrition strategy before substantial fatigue or hunger develops, rather than waiting until you're running low on energy.

Can I run a marathon using only gels?

Some runners successfully use gels as their primary calorie source alongside water and electrolytes.

Others prefer a combination of Hammer Gel and HEED, while runners expecting considerably longer finishing times may prefer incorporating Perpetuem.

Individual tolerance matters.

Should I use the sports drink provided by the marathon?

Only if you've tested that product during training and know that it works for you.

Race day is not the ideal time to introduce an unfamiliar sports drink.

What should I drink after a marathon?

Begin replacing fluid and electrolytes according to your needs. A recovery drink containing carbohydrate and protein can also help begin the post-exercise recovery process.

Build Your Hammer Marathon Nutrition Plan

Don't wait until race week to decide how you're going to fuel 26.2 miles.

Build the plan. Practise it. Refine it. Then race with it.

Choose Your Marathon Fuel

Portable race energy:
Shop Hammer Gel →

Drinkable energy + electrolytes:
Shop HEED →

Electrolyte support:
Shop Endurolytes →

Longer-duration endurance fuel:
Shop Perpetuem →

Post-marathon recovery:
Shop Recoverite →

Need the complete Hammer approach?
Visit the Running Nutrition Hub →