How to Fuel for a Marathon

Updated August 2026 by Hammer Nutrition UK

A successful marathon fuelling plan begins during training—not at the first aid station on race day. The goal is to arrive properly fuelled, begin consuming energy before fatigue develops and use products your stomach already knows.

This UK marathon guide covers the final days before the race, your pre-race meal, energy gels, sports drinks, electrolytes, hydration and recovery. It applies to road marathons, trail marathons and runners expecting to be on the course for three hours or longer.

Build your marathon nutrition plan during training

Your long runs are rehearsals for race day. Use them to test:

• Your breakfast and its timing
• The products you will carry or collect at aid stations
• How often you can comfortably consume fuel
• How much water works in cool and warm conditions
• Whether you prefer gels, a sports drink or liquid endurance fuel
• How your stomach responds at marathon pace

Record what you used, when you took it and how you felt. A simple written record is more useful than relying on memory after a tiring run.

Check the race organiser’s website well in advance. Find out which products are supplied, where the aid stations are located and whether you will need to carry your own bottles, gels or electrolyte capsules.

What to eat during the week before a marathon

As training volume falls during your taper, continue eating familiar balanced meals. Include carbohydrate foods such as rice, potatoes, pasta, bread, oats and fruit according to your normal dietary needs.

You do not need to turn every meal into a feast. Dramatically overeating may leave you bloated, disturb your sleep and create unnecessary stomach trouble.

In the final one to two days:

• Choose familiar meals rather than restaurant experiments.
• Make carbohydrate foods a clear part of each main meal.
• Reduce unusually fatty, spicy or high-fibre meals if they cause digestive problems.
• Drink normally throughout the day instead of attempting to “catch up” at night.
• Avoid excessive alcohol.
• Prepare breakfast, bottles and race fuel before going to bed.

What to eat before a marathon

Eat a familiar, carbohydrate-led meal approximately two to four hours before the start. A larger meal requires more digestion time; a smaller meal may be eaten closer to the race.

Possible breakfast options include:

• Porridge with banana and a small serving of yoghurt or milk
• Toast or a plain bagel with banana and eggs
• Breakfast cereal with milk or a suitable dairy-free alternative
• Rice with a small portion of familiar lean protein
• Toast and banana when your appetite is limited

Keep fat, fibre and heavy protein moderate if they tend to upset your stomach. Do not force down a meal simply because another runner swears by it.

Read our full guide to what to eat before a race for more examples and timing advice.

When should marathon runners start fuelling?

Do not wait until you feel hungry, weak or close to “the wall”. By then it may be difficult to recover your pace and comfort.

Begin your practised plan early in the race and take small servings regularly. Many runners find a consistent schedule easier to manage than reacting to hunger.

Sports-nutrition guidance commonly uses a broad carbohydrate range because runners differ greatly in speed, body size and tolerance. A plan that works for a two-and-a-half-hour runner may overwhelm someone racing for five hours.

Start with an amount you tolerate in training. Increase it only gradually, over multiple sessions, if additional fuel is genuinely required.

Choosing marathon fuel

Hammer Gel

Hammer Gel is a portable option for runners who prefer drinking plain water and taking calories separately. Carry enough for your complete plan unless the race supplies the exact product and flavours you have practised with.

Take each gel with water unless your established strategy says otherwise. Count every gel as part of your total intake.

HEED sports drink

HEED combines drinkable carbohydrate with electrolytes. It can suit runners who find a light-tasting drink easier than repeatedly taking gels.

If HEED is not supplied by the organiser, you will need a handheld bottle, running vest, support crew or drop-bag strategy. Do not assume an unfamiliar race sports drink will behave like HEED.

Perpetuem

Perpetuem is designed for endurance exercise lasting approximately three hours or longer. It provides carbohydrate, protein and healthy fat for runners who prefer sustained liquid fuel.

Running is more jarring on the stomach than cycling, so test Perpetuem carefully during long runs. A concentrated bottle or paste may be useful when carrying a standard bottle is impractical.

See our Perpetuem mixing guide for one-hour bottles, multi-hour concentrates and scoop calculations.

Marathon hydration

There is no single correct fluid volume for every marathon runner. Requirements change with body size, sweat rate, pace, humidity and temperature.

A cool spring marathon in the UK may require a very different plan from a warm race in direct sun. Use your training data and the actual forecast rather than following a fixed number copied from another athlete.

Good practice includes:

• Arriving normally hydrated without forcing excessive fluid before the start
• Taking manageable drinks at planned aid stations
• Adjusting intake when conditions become warmer or cooler
• Avoiding unnecessary overdrinking
• Knowing whether you will carry fluid or rely on the course

Thirst, sweat rate and changes in body weight during representative training runs can help inform a sensible plan. Athletes with medical concerns should seek individual advice from a qualified professional.

Do marathon runners need electrolytes?

Electrolyte needs vary between runners. Weather, sweat rate, clothing, pace and race duration all affect losses.

Endurolytes capsules, Endurolytes Extreme and Endurolytes Fizz provide different formats and strengths. Choose one during training and follow its current label instructions.

Electrolytes do not replace calories. If you use an electrolyte-only product, you still need a separate marathon fuelling plan.

Example marathon fuelling approaches

These examples show how products can be organised. They are not personalised prescriptions.

Water drinker

• Drink water according to your practised race plan.
• Use Hammer Gel at regular, tested intervals.
• Add an appropriate Endurolytes product according to conditions and label instructions.

Sports-drink runner

• Carry or arrange access to HEED.
• Sip it at regular intervals rather than drinking a large amount at once.
• Use water separately when required.
• Only add gels after counting the carbohydrate already supplied by HEED.

Long-duration runner

• Use a tested Perpetuem bottle, concentrate or paste as the primary fuel.
• Take measured portions every 15–20 minutes.
• Use separate water and electrolyte support.
• Carry a familiar backup such as Hammer Gel in case the original plan becomes impractical.

Common marathon fuelling mistakes

• Trying a new breakfast, gel or supplement on race day
• Waiting until energy levels fall before beginning to fuel
• Eating or drinking far more than was tolerated in training
• Taking gels without enough water
• Combining gels, sports drinks and food without counting the total intake
• Using the same hydration plan regardless of weather
• Relying on race-supplied products without checking the brand or flavour
• Leaving all nutrition decisions until the final week

After the marathon

Begin recovery once you have cooled down and can comfortably eat or drink. Replace fluid gradually and consume carbohydrate with quality protein.

Recoverite recovery drink provides carbohydrate, protein and recovery nutrients in a convenient drink. Follow the product instructions and continue with a balanced meal when your appetite returns.

Frequently asked questions

How many gels do I need for a marathon?

The answer depends on finishing time, the calories supplied by each gel and whether you also use a sports drink or other fuel. Calculate the plan by time rather than copying a fixed number. Test the full quantity during long runs.

Should I fuel by miles or time?

Time is usually more consistent because runners reach mile markers at very different speeds. Regular time intervals can also be programmed into a watch.

Can I run a marathon using only water?

Some very fast runners may complete the distance with limited intake, but most recreational runners benefit from a practised source of carbohydrate during a marathon. Individual needs vary.

Should I carry my own nutrition?

Carry your own products when the event does not supply exactly what you have tested. A running belt, vest, handheld bottle or planned support point can prevent unnecessary race-day improvisation.

What is the most important rule?

Nothing new on race day. Practise your breakfast, fuel, hydration, electrolytes and carrying method before the marathon.

Evidence and further reading

• Nutrition and Athletic Performance: Joint Position Statement
• International Society of Sports Nutrition Position Stand: Nutrient Timing

This article provides general information for healthy adults and is not personalised medical or dietary advice. Athletes with medical conditions, allergies or specialist dietary requirements should consult a qualified healthcare professional or registered sports dietitian.