Nutrition for the Marathon Runner

by: Nely Ward


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.

We have laid out rules for marathon training nutrition and using these rules, you will be able to effectively fuel your runs, boost your recovery, and be in the best shape come race day.


Let’s jump in!

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.

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 discussed above; roughly aim for 1 gram or protein for every 3-4 grams of carbs. This rule is the key to keeping you fueled between training sessions and should be at the top of your list when considering marathon training nutrition.

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.

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 the calories should come directly from sugar. Find a lower sugar option that tastes good to you.

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.

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 must eat potatoes, or use brand X gummies, or nut butters. Find what your body likes, can digest without issue, and stick to that.

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.

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 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.