Here’s what you should eat (and why) when training for a marathon.  

“So many people find themselves tired, drained and hungry (or nauseous) all of the time when they're marathon training and they deal with it because they assume that is part of the experience. It's not and shouldn't be! If you're fueling appropriately, you won't feel like you need to lay on the couch all day after a long run,” says Sara Hayes, founder and head coach at Mindful Miles.

So where do you begin? What should you eat when training for a marathon? We spoke to the experts to find out everything you need to know (and nothing you don’t) about what you should eat during marathon training.

What food should you eat when training for a marathon?

A diet filled with whole foods should be prioritised for those training for a marathon as these foods provide vitamins and minerals that benefit those training and can help reduce muscle cramps and stress fractures, says Alex Oskian, MS, RDN and nutrition coach at Working Against Gravity.

Try not to over complicate your nutrition. Instead, eat a well-balanced diet that prioritises wholefoods. Oskian recommends foods such as :

  • Spinach
  • Avocado
  • Black beans
  • Bananas 
  • Tofu
  • Berries
  • Leafy greens
  • Salmon
  • Rolled oatmeal
  • Dried fruit
  • Instant oats
  • Baked and sweet potatoes

Magnesium-rich foods, such as spinach, avocado and dark chocolate, help reduce muscle cramps. Foods high in vitamin D and calcium, such as berries, leafy greens, and Salmon, help strengthen bones, which reduces the risk of stress fractures. And a mix of slow and fast-digesting carbs fuel your training — that’s your oats, dried fruit, baked potatoes, and white rice.

There’s a wide variety of foods to choose from so you have a lot to play with!

Foods to avoid when training for a marathon

A well-balanced nutrition plan is recommended when training for a marathon. And while you have a lot more freedom of what to eat when training vs. on marathon day, there are some foods you want to avoid.

For example, fibre is a very important part of a balanced diet. Fibre helps keep your digestive system healthy and may help reduce your risk of heart disease and stroke, type 2 diabetes, and bowel cancer, as stated by the British Nutrition Foundation. And while fibre is essential, avoid eating foods too high in fibre before running (e.g., beans, broccoli, Brussels sprouts and cabbage) as these can cause stomach upset and digestive issues. But don’t stop eating fibre altogether — just time your intake around when you will be running.

Furthermore, drink fewer carbonated or sugary drinks — these can also cause stomach upset. Again, avoid drinking these in the hours before running — but the occasional treat once in a while is okay.

A lot of nutrition plans say you can’t eat or drink most of your favourite foods. But that’s not the most sustainable approach, often causing people to fall off track and binge, potentially undoing progress and negatively impacting recovery.

How do I plan my nutrition leading up to a marathon?

“The most important nutrition tip for marathon training is to make sure that you eat enough calories to support your activity levels. Mileage increases significantly over the duration of your training, and some of these training efforts can take multiple hours, which will increase your energy expenditure throughout the week,” says Oskian.

Not fuelling for performance is a common problem among first-time marathon runners. But eating enough is essential to fuel your training — the goal is not a body recomp; it’s to train and recover properly and reduce your injury risk. 

So, how should you plan your nutrition? 

Oskian mentions how most people focus their nutrition almost exclusively on carbs. But you need to include protein and fats in your meals as well. Aim for between 1.5-1.8g/kg of bodyweight of protein daily, which is in line with current research. Most of your protein should come from complete protein sources, such as animal protein (eggs, chicken, beef, etc.), soy, and quinoa. This ensures you get all the nutrients your body needs.

But if you’re looking for a protein boost, a recovery or protein bar such as STYRKRTHON can help you achieve your daily protein needs. Fat intake doesn’t have to be too high but present in your diet — 25-30% of total daily calories from fat is ideal for most people. Healthy fats include fatty fish, nuts, avocado, cheese, and extra virgin olive oil.

Practise your race day nutrition 

It’s a good idea to practise eating what you will eat on race day on the day of your weekly long run. 

Leaving race day nutrition to the last minute can cause stomach upset. And not knowing what to eat can lead to poor nutrition choices, potentially affecting your performance.

Practise your race day nutrition in training — eat the same breakfast you will before the race, see how you respond to energy gels, and practise your hydration strategy.

Don’t forget about hydration!

How much fluid you should drink is highly individual. But we can provide you with some guidelines!

For most of your marathon training runs, you won’t need to drink while running (as long as these sessions are less than 1 hour and not in extreme heat). But for long runs above 1 hour, it’s a good idea to drink water on your run. 

If you’re a salty sweater or are running in the heat (or in humid conditions), then add electrolytes to your fluids, such as an electrolyte powder or hydration tablet, to help prevent muscle cramping and a performance decline. 

Hayes recommends drinking between 443-681 ml of water per hour of running. You can use a water bottle, waist clip, or hydration vest to carry fluid while running.

Furthermore, because hydration needs are individual, we recommend calculating your sweat rate to find out how much fluid you should be taking/hour. We go into more detail on how to do so in our article, why is hydration important in sport?

Related: How to Stay Hydrated During a Marathon?

How many calories should I eat when training for a marathon?

The total number of calories you need daily depends on your existing bodyweight and how often you run/train. The goal when marathon training is not to lose weight — it’s to fuel your body for performance and recovery.

Eat a balanced diet consisting of carbohydrates, fats, and protein. You can track your calories if you want using an app such as MyFitnessPal. This is not necessary for all runners.

Although, you may find that tracking your calories for even a few days can prove useful. You may notice you’re not eating protein, enabling you to make changes to your nutrition to improve recovery. But you do not need to track calories — it’s an added tool that can help you achieve your nutritional goals. 

Instead, we’d recommend weighing yourself weekly to make sure there are no sudden drops or gains in weight. Adjust your food intake as needed. There is no need to make it more complicated than needs be!

Don’t overcomplicate your marathon nutrition 

Your marathon nutrition does not need to be complicated. Increase your calories as needed, make sure to eat plenty of carbs, fats, and protein, and drink plenty of water (and electrolytes if needed) to fuel your training.

Don’t overcomplicate it — fuel for performance and keep a training journal to monitor your progress.

Key takeaways:

  • Follow a balanced nutrition plan and focus on eating whole foods 
  • Eat to fuel your performance 
  • Get your macronutrients right — protein and fats are important!
  • Don’t overthink it 

For more advice on what to eat before, during and after a marathon, you can read our blog post titled: Marathon Nutrition: The Ultimate Guide for Runners.