How to Actually Eat More Carbs During Marathon Training

Fuel and Flow with Jess
A Run Vault series on nutrition and hydration for performance

Marathon season is here. The long runs are getting longer, your weekly kilometres are climbing, and suddenly every runner on Instagram seems to be talking about carbohydrates. As a Sports Nutritionist, one of the most common questions I hear this time of year is: “I know I need to eat more carbs, but how do I actually do it?”

As a runner you probably already understand that carbohydrates are important for performance. You know you should be eating more as your training volume increases, yet when it comes to putting that advice into practice, you aren’t sure where to start.

If you’re training for a marathon, half-marathon, or ultra-marathon, this guide will help you understand why carbohydrates matter and provide practical ways to increase your carbohydrate intake without feeling overwhelmed.

Why Are Carbohydrates Important for Marathon Training?

Carbohydrates are the body’s preferred fuel source during endurance exercise. When you eat carbohydrates, they are stored as glycogen in your muscles and liver. During your runs, particularly intervals, tempo sessions, and long runs, your body relies heavily on these glycogen stores to produce energy.

As your training load increases, so does your carbohydrate requirement. Without adequate carbohydrate intake, runners may experience:

• Early fatigue during training sessions
• Struggling to recover between sessions
• Reduced training quality
• Increased perceived effort
• Persistent hunger
• Difficulty maintaining pace
• Hitting the wall during long runs

Simply put, if you’re asking your body to do more work, you need to provide it with more fuel.

The Biggest Marathon Nutrition Mistake I See

Many assume that increasing carbohydrates means eating a huge bowl of pasta every night. While pasta can certainly play a role in a runner’s diet, marathon nutrition is about consistently meeting your carbohydrate needs throughout the day, not relying on one meal.

It’s not about dramatically changing your diet. Making small adjustments that increase your overall carbohydrate intake across breakfast, lunch, dinner, snacks, and training sessions is key.

How to Increase Carbohydrates During Marathon Training

Rather than overhauling your entire nutrition plan, look for opportunities to add carbohydrates to meals and snacks you already enjoy.

Breakfast

Current breakfast: Eggs on toast

Easy ways to add carbs:

• Eggs on toast
• A banana
• A glass of juice
• Additional toast with jam or honey

Snack

Current snack: Greek yoghurt

Easy ways to add carbs:

• Greek yoghurt
• Muesli or granola
• Fresh fruit
• Honey

Lunch

Current lunch: Chicken salad

Easy ways to add carbs:

• Chicken and rice bowl
• Chicken wrap with fruit
• Sandwich with a side of crackers
• Adding a bread roll to your meal

Dinner

Current dinner: Protein and vegetables

Easy ways to add carbs:

• Protein, vegetables, and rice
• Protein, vegetables, and pasta
• Protein, vegetables, and potatoes
• Stir-fry with noodles

Easy High-Carbohydrate Snacks for Runners

If you’re struggling to meet your carbohydrate requirements, snacks can make a significant difference. Some simple runner-friendly options include:

These foods can help increase carbohydrate intake without making meals excessively large.

How Many Carbohydrates Do Marathon Runners Need?

Carbohydrate requirements vary depending on training volume, body size, and training goals.

As a general guide:

• Moderate training: 5–7g carbohydrate per kilogram of body weight per day
• High-volume endurance training: 6–10g/kg/day
• Very high training loads: 8–12g/kg/day

For a 70kg runner, this may equate to anywhere from 350–700g of carbohydrate per day depending on the phase of training. This is often much higher than runners expect, which is why many unintentionally under-fuel.

Fuel the Work Required

One of my favourite principles in sports nutrition is simple: Fuel the work required.

As your marathon training increases, your nutrition should increase alongside it. Many runners are comfortable increasing their weekly kilometres but hesitate to increase their food intake. However, training adaptations occur when your body has access to the energy required to support them.

The goal isn’t simply to survive marathon training. The goal is to train well, recover well, and arrive at the start line feeling strong, energised, and confident.

If you’re constantly feeling tired, hungry, or struggling to recover, it may not be your training plan that’s the problem. It may be that you’re not eating enough carbohydrates to support the work you’re asking your body to do.

Don’t Forget Your Training Fuel

One of the easiest ways to increase your carbohydrate intake is during your training sessions.

If your run lasts longer than 60–90 minutes, consider fuelling with:

• Gels
• Chews
• Lollies
• Carbohydrate drink mixes

Not only does this help you meet your carbohydrate requirements, but it also trains your gut and prepares you for race day.

The Bottom Line

If you’re increasing your kilometres, you need to increase your fuel. Marathon training is demanding, and one of the biggest mistakes I see runners make is trying to train like an athlete without eating like one. More kilometres require more carbohydrates. More carbohydrates support better training, recovery, and performance.

So, if marathon season has you wondering whether you’re eating enough carbohydrates, start by looking for small opportunities to add fuel throughout your day.

Add the banana.
Add the extra slice of toast.
Add the rice.
Add the sports drink.

Because every kilometre of training requires fuel.
Your future self at kilometre 35 will thank you for it.

Need help working out exactly how much you should be eating?

I’d love to help. At We Run Nutrition, I work with runners of all levels to build practical, evidence-based nutrition strategies that fit real life, and help you get more from your training. Reach out on Instagram at @werun_nutrition.

Jesikah Ings is a qualified nutritionist specialising in fuelling and hydration for runners and endurance athletes. An accomplished athlete herself, she combines scientific evidence with practical, real-world experience. You can find her work at We Run Nutrition.