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FUELLING YOUR MARATHON

BEFORE. DURING. AFTER.Simple, scientifically-backed fuelling steps to help you perform, recover, and progress.

FUELLING YOUR MARATHON

There is nothing quite like the marathon. A test of physical endurance, mental resilience, and sheer determination – 
yet when you cross that finish line, the sense of achievement stands alone in sport. It is the legendary distance for a reason.

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marathon fuelling: making it work

Marathon performance is underpinned by several key physiological factors.

While training develops these attributes, optimal marathon performance cannot be achieved without an effective fuelling strategy. The marathon is predominantly an aerobic event, demanding sustained output from your body’s oxidative energy systems across 42.2 km of continuous effort.

You’re running at a moderate aerobic intensity – the marathon sits at the challenging intersection where effort feels controlled yet purposeful. For those who categorise their training by heart rate, this typically places you somewhere between Zone 2 and Zone 3, though your precise zone will shift depending on your level of fitness.

✓

High Oyxgen Demand

Maximal oxygen uptake (V̇O2max), the maximum amount of oxygen your body can utilise during exercise.

✓

Sustainability

The fraction of your V̇O2max that can be sustained for several hours.

✓

Running Economy

Which reflects how efficiently you use oxygen at a given running speed.

✓

Durability

Your ability to resist fatigue and maintain performance as physiological stress accumulates.

THE MARATHON FUELLING DEMANDS

At these intensities, carb oxidation rates are high – commonly around 1.5–3.5 g per minute – depending on your race pace, metabolic efficiency, and fuelling status, equating to a total 
carb use of 500–600 g over the race. In addition, energy expenditure remains high for hours rather than minutes. 
There’s no hiding place.

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SO, HOW DO YOU GET YOUR
MARATHON FUELLING RIGHT?

The right products, in the right quantities, at the right time (or as close as you can get to it).
Let's break that down.

 

FUELLING method

[-48 HRS]

 

Having tapered your training load, your focus two days out turns to maximising your energy reserves without stressing your gut. Your body stores only a finite amount of 
carbs – and at marathon intensity and duration, you’ll be drawing on those stores heavily from the moment you start. This makes carb loading in the 48 hours before your race 
not simply a recommendation, but a critical component of your race-day preparation.

Carb accuracy and a steady approach will serve you better than over-enthusiastic loading.

To maximise glycogen stores, aim for a total daily carb intake of 10–12 g per kg. This represents 750–900 g of carbs for a 75 kg runner. To achieve that volume without discomfort, go for familiar, low-fibre and low-fat foods, and look to suitable carb-dense snacks and drinks to contribute. Remain steadily hydrated leading into the race.

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[-24 HRS]

 

The day before is all about repeating this target, again gently and manageably. Spread your intake evenly across the day, rather than piling up a mountain of pasta in the evening.

Choose low‑fibre, low‑fat foods you can digest cleanly. The objective now is easy storage, 
not experimentation. Your hydration, supported by electrolytes, should continue steadily 
in the background. Science in Sport products can be used alongside everyday foods to help 
you consistently hit your carbohydrate targets and arrive on the start line fully fuelled and 
ready to perform. A practical example of how to structure a high-carb day before the marathon is shown in the following visual guide

Below is an example of an increased-carb daily meal plan providing approximately 780 g of carbs (approximately 10 g per kg of body mass for a 75 kg runner), alongside ~1000 mg of dietary nitrates for nitrate loading, with strategic use of GO TART CHERRY and GO REST 
& RECOVER SHOT to support recovery and sleep. This is intended as an example only, not 
a one-size-fits-all plan. Portion sizes should be adjusted to suit your own body mass and 
energy needs. Foods can be swapped based on your personal preferences, dietary requirements, and what you find practical and enjoyable to follow.

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[DAY BEFORE]

BREAKFAST

100 g breakfast cereal (i.e., crisped rice cereal) with 300 ml milk + 1x toasted bagel with jam + 300 ml orange juice + 
1x GO NITRATES SHOT + 1x GO TART CHERRY

[DAY BEFORE]

Training (shake-out run)

Sip on 1x GO HYDRO STICK PACK in
500 ml water

[DAY BEFORE]

mid-morning snack

1x GO FUEL ENERGY OAT BAR + 1x banana

[DAY BEFORE]

lunch

Large portion (250 g) cooked white rice + 1x cooked chicken fillet + sauce of choice + small garnish of veg/salad + white crusty bread roll + DESSERT: 200 g natural yoghurt + tablespoon honey + 30g granola and chopped banana and strawberries

[DAY BEFORE]

afternoon snack

1x BETA FUEL ENERGY CHEW +
1x GO FUEL ISOTONIC SPORTS ENERGY DRINK

[DAY BEFORE]

dinner

Large portion (250 g) cooked white rice + 1x cooked salmon fillet + sauce of choice + grated beetroot + white crusty bread roll, DESSERT: 250g rice pudding + 1x tablespoon 
of jam + 1x GO NITRATES SHOT + 1x GO TART CHERRY

[DAY BEFORE]

pre-bed

1x toasted bagel with jam + 

1x GO REST & RECOVER SHOT

race day

Overnight, liver glycogen naturally falls. Restoring it is essential, regardless of how well you loaded the day before. No matter your start time, your main pre‑race meal should be light, safe, and easy to digest. At approximately 3 g of carbs per kg of body weight, a 75 kg athlete is looking at around 225 g of carbs. This ensures your muscle and liver glycogen stores are topped up ahead of the race.

Hydration at this stage should be calm and deliberate, with volume easing up gradually to avoid bloating.

[-03 hours]

pre-race meal

80 g breakfast cereal (e.g., crisped rice) with 250 ml milk + 1x toasted bagel with jam + Sip on 1x BETA FUEL ENERGY DRINK MIX mixed in 600 ml water + 1x GO NITRATES SHOT

[-01 hour]

pre-race snack

In the final hour, you’re simply maintaining your energy availability. A small dose of fast-digesting carbs (high-quality energy snacks are ideal) is all you need to get you to the start line.
PRE-RACE: 
1x BETA FUEL ENERGY CHEW + sip on additional fluids

DURING

Based on your target time, work out your mid-race fuelling quantities and timing. 80–120 g of carbs per hour is recommended, starting early and continuing consistently through the race.

For most runners, this means about 40 g of carbs about every 20–30 minutes. Stick to your 
pre-planned fuelling intervals. Missed early opportunities can prove very costly later on. Such recommendations are underpinned by emerging research from Science in Sport suggesting these doses deliver a meaningful performance advantage, supporting higher carb oxidation rates, better sustained energy output, and improved running economy across the full race distance.

To achieve these ambitious targets, dual-source gels are essential for such high carb intakes. Incorporating both maltodextrin and fructose, they increase the rate at which carbs can be digested, absorbed, and utilised by your muscles, compared with single-source formulations. This provides a decisive physiological advantage over marathon distance and duration.

You should also drink to a plan, based on race conditions and your sweat rate. Electrolyte intake will help to maintain fluid balance. Caffeine can also be particularly effective later in the race. It helps sustain your focus and dull feelings of fatigue, providing a physical and mental boost when you need it most.

The below is an example marathon fuelling strategy informed by recent cutting-edge research. Based on SiS recommendations of up to 80 g of dual-source carbs per hour and 200 mg of caffeine, this mixed fluid-and-gel plan is intended for illustrative purposes only. You should practice and refine your fuelling strategy in training to train the gut to tolerate high carb intakes and the body to use them effectively, while adjusting caffeine to individual needs, tolerance, and preferences.

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[00 MINS]

TOP-UP

1x BETA FUEL ENERGY GEL + 50-100 ml of water

[30 MINS]

HYDRATE

250 ml BETA FUEL ENERGY DRINK MIX

[60 MINS]

HYDRATE

250 ml BETA FUEL ENERGY DRINK MIX

[90 MINS]

TOP-UP + REPLACE

1x BETA FUEL + ELECTROLYTE ENERGY GEL 
+ 50-100 ml of water

[120 MINS]

TOP-UP

1x BETA FUEL + NOOTROPIC ENERGY GEL + 50-100 ml of water

[150 MINS]

TOP-UP + CONTINUE

1x BETA FUEL ENERGY GEL + 50-100 ml of water
Continue fuelling every 30 minutes until the finish

AFTER

Your recovery begins the moment you stop moving. Glycogen restoration, muscle repair, and rehydration are crucial and time‑sensitive after the marathon.

Prioritise carbs, protein, fluids, and electrolytes as soon as you can. Keep it simple – recovery drinks provide a controlled, efficient solution without the digestive burden.

[+30 MINS]

POST-RACE

1x BETA RECOVERY POWDER
1x GO TART CHERRY

[+01 HOUR]

EASY MEAL

Following your initial BETA RECOVERY POWDER drink, aim for a light, easily digestible meal to continue the recovery process. A target of around 1-1.2 g of carbohydrate and 0.3 g of protein per kg of body weight is recommended. For a 75 kg runner, 
this equates to approximately 75-100 g of carbohydrate 
and 20–30 g of protein. This meal will help further replenish glycogen stores, support muscle repair, and prepare you for 
your next training session. Continue to consume carbohydrate and protein regularly throughout the recovery period and maintain steady hydration to replace ongoing fluid losses.

[NIGHT]

PRE-BED

1x REST & RECOVER SHOT 

QUALITY. VOLUME. TIMING.

Fuelling to improve your marathon

Marathon success is built on consistency and discipline. Improvisation isn't an option. Smart fuelling habits, reinforced through repetition, make the difference on race day. This is where your preparation shows – not in dramatic moments, but in steadiness under pressure.

By trusting the best endurance nutrition science, you can develop a strategy that goes the distance. This builds the confidence and resilience that sees you through, especially later in the race when fatigue threatens.

To sharpen your race-day fuelling:

  • Test your race plan when you're tired, as well as when you're fresh
  • Practice your carb timing until it's instinctive
  • Train your gut with the same focus as your legs and engine

Quality fuel, delivered in the right quantities, at the right time, plays 
a big part in determining performance. Fuelling smartly turns all your training work into something you can actually access later in the race, delivering a marathon effort you can be proud of.

marathon race & training pack

The complete pack to fuel every step

✓ hydro+
✓ beta fuel  + nootropics
✓ beta fuel chews
✓ beta fuel gels
✓ recovery powder