Marathon training places a huge demand on the body. While mileage, workouts, and pacing get most of the attention, fueling is often the factor that determines whether training is absorbed or simply survived. Getting marathon fueling right isn’t just about race day, it starts weeks and months earlier in training.

This guide breaks down how to fuel effectively during marathon training and how to put it all together on race day.

Why Fueling Matters in the Marathon

At marathon pace, your body relies heavily on carbohydrates. While fat is an important fuel source, it cannot provide energy quickly enough to support sustained marathon intensity on its own. Your stored glycogen is limited, and once it’s depleted, your energy levels begin to decline and you might start to bonk!

Consistently fueling helps you:

  • Maintain pace for longer

  • Recover better between sessions

  • Train consistently

  • Reduce the risk of late-race fatigue

Fuelling During Marathon Training

Day-to-Day Training Fuelling

Fuelling should match the demands of your training. On easy or low-intensity days, carbohydrate needs are lower, but on harder or longer days, intake should increase to support performance and recovery.

Under-fueling during training can lead to:

  • Poor session quality

  • Increased fatigue

  • Higher injury risk

  • Plateaued performance

Fuelling Key Marathon Sessions

Long runs and marathon-pace workouts are where fuelling becomes especially important. These sessions place the greatest demand on glycogen stores and are also your opportunity to practise race fuelling so your body is responding in the same way as it would on race day!

During these sessions:

  • Take in carbohydrate during the run

  • Practise timing and spacing of gels or drinks

  • Train your gut to tolerate fuel at marathon intensity by increasing your dose of carbohydrate gradually

How Much Carbohydrate Do You Need?

General guidelines for marathon training and racing fall in the range of:

  • 30–60 g of carbohydrate per hour for most runners

  • Up to 90 g per hour for faster or more experienced athletes

The exact amount depends on pace, experience, and gut tolerance. The key is to find a level you can tolerate consistently and practise it in training.

Signs you may be under-fuelling include:

  • Energy dropping late in long runs

  • Difficulty holding marathon pace

  • Excessive fatigue between sessions

Fuelling in Race Week

The Taper

As training volume decreases, energy expenditure drops, but carbohydrate intake shouldn’t fall dramatically. The goal of the taper is to reduce fatigue while allowing glycogen stores to rebuild.

This is where many runners go wrong by unintentionally under-eating.

Carbohydrate Loading

Carb loading increases the amount of glycogen stored in your muscles ahead of race day.

A simple approach:

  • Begin 36–48 hours before the race

  • Prioritise easily digestible carbohydrate

  • Reduce fibre and very heavy meals

Carb loading doesn’t mean overeating, it means shifting the balance of your intake toward carbohydrate.

Race Day Fueling

Pre-Race Nutrition

Aim to eat 2–4 hours before the start, focusing on carbohydrate with minimal fat and fibre. This tops up liver glycogen and provides readily available energy.

A small carbohydrate intake (gel or drink) in the final 10–15 minutes can also help stabilise blood glucose at the start.

Fueling During the Race

A simple, effective strategy:

  • Start fuelling early (within the first 30 minutes)

  • Take small, regular doses

  • Combine gels and fluids as practised in training

Hydration and sodium intake should support your fuelling plan, not override it. Over-drinking can be just as problematic as under-drinking.

Common Marathon Fuelling Mistakes

  • Waiting too long to fuel

  • Trying new products on race day

  • Underestimating carbohydrate needs

  • Ignoring sodium and hydration

  • Fuelling well in training but not executing on race day

Most marathon fuelling problems are planning or execution issues, not fitness issues.

Putting It All Together

The best marathon fuelling strategy is:

  • Practised in training

  • Simple to execute

  • Matched to your pace and tolerance

Fuelling shouldn’t feel stressful on race day — it should feel automatic.

Final Thoughts

Marathon fuelling is not about perfection. It’s about preparation. When fuelling is dialled in during training, race day becomes about running well — not managing energy crises.

Train the body. Train the gut. Trust the plan.