10 Rules of Marathon Training Nutrition

In this post, we dive into marathon training nutrition and give our 10 rules for how to eat and fuel when in marathon training mode!

Fueling for a marathon, and nutrition in general, is now widely recognized to be just as important as training for any athlete.

While training for a marathon you want to make sure your food is working just as hard as you are.

This is why we have laid out 10 rules for marathon training nutrition.

Using these rules, you will be able to effectively fuel your runs, boost your recovery, and be in the best shape possible come race day.

Let’s jump in!

marathon training nutrition 1

1. Understand your metabolic needs

Every marathon training plan involves running a high volume of miles to increase your aerobic capacity.

During these training sessions – and on race day – runners can burn up to 100 calories per mile.

That’s 1,500 calories for a 15-mile training session.

These calories must be replaced as part of your marathon training nutrition plan.

A runner eating in a calorie deficit will begin to break down muscle to compensate.

This is bad news; our muscles are a storage container for vitamins, minerals, and carbohydrates, which we don’t want to lose too much of.

Pairing this with the protein structure of muscle makes them the primary target for fuel when you don’t consume enough food.

Step one in marathon training nutrition is to make sure you are eating enough calories.

Also understand your calorie consumption varies slightly from day to day depending on the intensity and length of the training sessions, but overall training for a marathon means eating more food.

2. Keep Macros in Balance

The primary fuel for marathon runners without a doubt is the carbohydrate.

This macronutrient should be make up the majority of what you are consuming.

During intense training phases (where mileage and tempo increase) the body will need more carbohydrates to fuel workouts and replenish stores.

Aim to eat between 3.5 – 4.5g per pound of body weight each day on these intense days. For a 120lb runner this equates to 420-540g of carbs per day.

On lighter training days and rest days the goal for carb consumption should be between 3.0 – 3.2g per pound of body weight.

Protein is the next most important macronutrient to help replenish muscle break down.

On training days aim for 0.7 – 1.0g of protein per pound of bodyweight while non-training days should be between 0.5 – 0.7g per pound of body weight.

Fat is the final macro and is needed to help with vitamin storage and hormone production but should be kept around 0.5g per pound of body weight on training and non-training days.

  • Related: Here’s What To Eat After Running!
  • marathon training nutrition avocado

    3. Obey the Eating Window

    Long endurance runs will deplete carbohydrate storage in the body.

    To help mitigate this, eat an easily digested carb-based snack 30-45 minutes prior to a run. A sports gel or piece of fruit is perfect.

    Within an hour of finishing your training session replenish your carb stores by eating a full meal using the macronutrient quantities dicussed above; roughly aim for 1 gram or protein for every 3-4 grams of carbs.

    This rule is the key to keeping you fuelled between training sessions and should be at the top of your list when considering marathon training nutrition.

    4. Eat clean foods

    Whole foods are the easiest for a body to digest and pull nutrients from.

    Eating the cleanest sources of foods that are available to you will ease digestion and increase nutrient absorption, aiding in the recovery process of your marathon training.

    When shopping for foods to eat during your marathon training go with organic, natural, and as close to whole foods as you can.

    5. Minimize added sugars

    Almost all marathon runners-in-training turn to high energy sports fuel such as energy gels and sports drinks.

    When picking these products look for unnecessary added sugars. You want a quick source of carbohydrates but not all of the calories should come directly from sugar.

    Find a lower sugar supplement that tastes good to you.

    6. Keep snacks on hand

    As we’ve mentioned before, marathon runners burn calories like crazy.

    To keep calorie count high, especially on training days, keep pre-packed snacks with you wherever you go.

    These snacks should fall under all the rules we’ve laid out thus far. They need to be primarily carbslow in added sugars, a clean source of energy, and perhaps most importantly something you enjoy.

    Packing snacks before the day starts gives you a plan to fuel your training and a reason to stay away from the candy bars.

    marathon training nutrition pancakes

    7. Find the Right Foods

    We all digest foods differently and if your stomach gets upset from a certain gel or has trouble digesting a particular food, then don’t eat it.

    There’s no hard and fast rule saying marathon runners have to eat potatoes, or use brand X gummies, or nut butters.

    Find what your body likes, can digest without issue, and stick to that.

    8. Hydrate, Hydrate, Hydrate

    Hydration is critical for muscle health (preventing cramps), body temperature regulation, as well as vitamin and mineral absorption.

    When you’re out on the road putting your miles in, the body is losing a considerable amount of water through sweat; the average person will sweat between 0.8 and 1.4 liters for every hour of intense exercise.

    Taking small sips of water every 15-20 mins during a run will go a long way to replace what is lost.

    stay hydrated marathon training nutrition

    9. Supplement Where Needed

    Natural food supplements, such as ginger and fish oil, are great for joint health and inflammation.

    These two supplements will aid in the recovery process and keep you on the road for longer.

    Make them part of your marathon training nutrition plan.

    In addition to those, BCAAs can be used to prevent muscle break down, while a multivitamin will provide B-12 to combat fatigue, D3 and calcium for bone health, and iron for better oxygen transport to the muscles.

    10. Don’t Try Anything New on Race Day!

    All these rules for marathon training nutrition should be practiced during training!

    Race day is not the day to try something new!

    Practice fueling, hydrating and experiment with gels and energy sources prior to the day of your marathon.


    Marathon training nutrition doesn’t have to be difficult, but it should be taken seriously.

    Following these 10 rules for eating during marathon training will increase your energy on the road, keep your muscles primed for training days, ensure you are getting the calories and nutrients your body needs, and prepare you for race day.

    bonus tip! :

    11. Have a Meal Plan!

    Alright, I know we only said 10 rules, but the 11th – and possibly most important rule – is to have a Marathon Training Meal Plan in place.

    Where to start?

    Check out our completely free, downloadable marathon training meal plans!

    We include:

    • Sample 1-week marathon meal plan
    • Sample ‘week before your marathon’ meal plan
    • Sample vegetarian 1-week marathon meal plan
    • Sample vegetarian ‘week before your marathon’ meal plan

    Check out our marathon training meal plans!

    Thomas Watson

    Thomas Watson

    Thomas Watson is an ultra-runner, UESCA-certified running coach, and the founder of MarathonHandbook.com. His work has been featured in Runner's World, Livestrong.com, MapMyRun, and many other running publications. He likes running interesting races and good beer. More at his bio.

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