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How to Fuel Your Body Best During Marathon Training

Author: Maria Fischer • Fact checked by: Tara D. Thies • April 14, 2021

How to Fuel Your Body Best During Marathon Training

A marathon is a running event with a distance of 42.195 km, or about 26.2 miles. That is a long distance for your body to run in a single race. In order to optimize your marathon performance, you need to train well in advance — and training doesn’t just involve weeks of running. Nutrition is an important part of training for a marathon, too. 

The food you consume in the weeks — and more importantly, days — leading up to race day can make or break your performance. If you’re training for a marathon, you want to follow a proper nutrition plan. 

Don’t know where to start? Keep reading to learn how to fuel your body best during marathon training. 

What should I eat while training for a marathon or a half marathon?

First things first: you need to make sure your diet includes enough calories to support increased activity. If you participate in moderate to intense activity each day (which you should be if you’re training for a marathon), then you need to consume at the very least 2,000 calories per day. This is on the low end of the spectrum — according to the International Society of Sports Nutrition (ISSN), a 110-220-pound athlete could need up to 7,000 calories per day in order to support the amount of activity required for marathon training. It’s often recommended that runners training for a marathon should consume 19-21 calories per pound of bodyweight for 1–1.5 hours of strenuous activity per day. If your training schedule calls for 2-3 hours of strenuous activity, then this amount may need to be bumped up to 22-24 calories per pound of bodyweight. If you’re up to 3+ hours of running per day, caloric intake for marathon training should increase to around 25-30 calories (or more) per pound of bodyweight.

Your calories shouldn’t just come from anywhere — you need to eat a well-balanced diet that includes adequate amounts of whole grains, fruits, vegetables, lean protein and healthy fats. Though unhealthy drinks and snacks may make it easy to meet your calorie goals, a diet of soda and sugar will not lead to optimum performance. 

In general, Gainful suggests aiming to stay around the range of 45-60% of calories from carbohydrates, 15-30% from fat and 10-25% from protein, but for marathon runners, an ideal macronutrient breakdown might be closer to 55-60% carbohydrate, 20% fat and  20-25% protein. If you’re an endurance athlete, your body is burning through a lot of fuel during your workouts, so this means you’ll need higher stores of carbohydrates than you would if you were mainly strength training or doing HIIT workouts. 

Using these caloric and macronutrient guidelines, create a meal plan filled with healthy whole foods. To ensure your body is properly fueled throughout the entire day, you should have at least three meals and two snacks per day. Breakfast might look like oatmeal made with low-fat milk or nut milk with a sprinkle of protein powder and a side of fruit, or a piece of whole wheat toast topped with natural peanut butter, avocado or eggs and a side of berries. Your morning and afternoon snacks might be an apple and pretzels with peanut butter or Greek yogurt topped with granola. Then for lunch, you could have beans, salmon, chicken, lean beef — any form of healthy protein. Make sure you get in some veggies and fats. (A salad with olive oil and shredded cheese could do the trick.) Then for dinner, you could have more healthy protein with brown rice, sweet potatoes or quinoa and veggies with butter. 

You can get creative with your training meal plan, so long as you meet your caloric and nutrient needs. 

Carbohydrate recommendations for marathoners

Carbohydrates play an especially important role in marathon training. (Just ask any marathoner who has taken part in a pasta dinner the night before race day!) 

Carbs are a great source of energy, and you need a lot of energy to cover 26.2 miles. According to the ISSN, athletes following intense running schedules need to eat between 5-8 grams of carbohydrates per kilogram of bodyweight per day (5-8/kg/d) during training. 

Many marathon runners partake in “carb loading.” That’s because most carbohydrates are stored as glycogen in your muscles and liver. Glycogen is your body’s most easily-accessible form of energy, and it’s what helps keep your body going during long runs.  

When it comes to carb loading, remember: Timing is everything. You don’t need to load up on carbs if you’re still in the short distances phase of your training. As you start building up to longer runs (around six weeks before race day), you can begin to practice carb loading. Start eating more carbs and less fat and protein. This will help you get a sense of which carb-heavy meals agree with your stomach during a run — incredibly useful information on race day. The last thing you want to do is scarf down your pasta dinner the night before your race only to discover your stomach disagrees with the sauce. 

One week before the race, start stocking up on the carbs you’ll need before your race, during the race and after. Think easy-to-digest carbs like energy bars, energy gels, energy chews, sports drinks, electrolyte drinks or crackers. When you’re two or three days away from the race, you’ll want to switch to a super carb-heavy diet. Getting 70% of your total calories from carbohydrates three days leading up to your marathon will help maximize your stored carbohydrate in muscles (glycogen) and help boost your performance. The night before the race, you can indulge in your pre-race pasta, but don’t overdo it. You don’t want to wake up on race day with a heavy, full stomach. Then three hours before the start of your race, eat around 150 grams of carbs — you can get your carbohydrates through toast, a bagel, oatmeal or a smoothie. 

By strategically eating carbs leading up to the race, your body will be primed to store and use glycogen to get you through your marathon. 

Foods and drinks to avoid during marathon training

As you know from above, it’s important to make sure you’re eating more calories while training, but eating more of the wrong foods can slow you down. When your fuel is cleaner, less processed and overall healthier, you’ll find improvements in your performance. 

When training for a marathon, you should avoid sugary sodas, energy drinks that contain stimulants and caffeine as the primary source of energy, spicy foods, deep fried foods and highly processed foods. ?Because the body requires more energy to digest fatty foods, consuming excess fats on race day could cause your performance to suffer. The key is to consume foods that are easy on your stomach and give your energy levels a boost (but you want natural energy — sugary energy drinks don’t count). Swap water or a hydration formula for sodas and energy drinks; swap easy-to-digest carbs for extra creamy or spicy foods; swap whole foods for fried foods or processed foods. If you have a history of gastrointestinal problems or gastrointestinal distress, you may also want to avoid dairy on the day of the race and the days leading up to the race. Many marathoners also skip their morning coffee on race day, as it is diuretic. 

Cutting out high-fat, fried foods will make all the difference in your marathon training. 

What should I eat on race day morning?

After eating a carb-heavy meal the night before running a marathon, you’ll want to keep up the carb loading on race day morning. Make sure you have easy-on-the-stomach carbohydrates at least an hour before the race. Some suggestions include a smoothie, a banana with peanut butter, toast and jam, a bagel with nut butter, a granola bar, or a bowl of fruit. 

Do not introduce new or unfamiliar foods into your diet on race day, as you don’t want to take the chance of having to deal with unexpected stomach issues as you run your marathon.

What should I eat and drink during a marathon? 

You might be tempted to skip the snacks during the marathon and power through your run. According to data from the research center at RunRepeat, an athletic footwear review site that analyzed 107.9 million race results from over 70 thousand events in 209 countries between 1986 and 2018, the average marathon race finish time is currently 4:32:49. Whether your time falls before or after that, 4+ hours of nonstop running is a lot of time for your body to keep moving. You’ll want to properly fuel your body with food during the marathon. Aim to have 30-60 grams of simple carbohydrates per hour. These carbs can come from sports drinks, energy bars, energy gels, energy chews and bananas. You don’t have to stop and eat — just take small bites as you continue your run. A good rule of thumb is to take in a dose of carb fuel every 20-30 minutes and follow that with three swigs of your water bottle or hydration pack beginning 15 minutes before the start of the race. If you are taking this fuel in from sports drinks containing carbs, you get two-for-one fuel and hydration; if you take a gel, follow that with water.

Also make sure you’re properly hydrating during the race. To prevent dehydration during a race, drink 1.5-2.5 cups of fluid 15 minutes before the race begins and then drink 1 cup of fluid at regular intervals to replace fluid loss — approximately 3 swigs every 15 minutes. Fluids include plain water, sports drinks or isotonic drinks. (Avoid soda and fruit juices as these are highly concentrated fructose and may upset your stomach.)

You can also refer to the American College of Sports Medicine Joint Position Statement for more guidelines and suggestions for race day fuel. 

What to eat after running a marathon

Once you’ve crossed that finish line, you should immediately eat 200-300 easily-digestible calories from carbohydrates and protein to maintain blood sugar levels, replenish glycogen stores and repair muscle tissue. Some suggestions include a potassium-filled banana with peanut butter, protein bar, or chocolate milk. Then, you’ll want to continue to consume good sources of carbohydrates, such as pasta, rice or bread, for 3-4 hours after the race in order to maximize glycogen resynthesis.

If you’re hitting the bar after the race, make sure you’re not celebrating on an empty stomach. Alcohol can impair your recovery process, so you’ll want to have your post-race fuel and replenish your electrolytes before having that celebratory beer.

The best protein powder for runners

We’ve covered the importance of carbs in this marathon training guide, but don’t forget about protein: For runners, the ISSN recommends an intake of 1.4-1.8 grams of protein per kg body weight per day.

Using protein powder is an easy way to get the protein you need for marathon training. The fastest digesting proteins are the proteins that have been separated from their whole food source and turned into protein powder. Protein powders are usually consumed as a liquid without much fiber or fat, and generally speaking, liquids digest faster than whole foods. So that means protein powder supplements poured into your drinks will be absorbed more quickly than most dietary protein, allowing you to get the protein your body needs for recovering from running long distances. Consuming protein shakes or drinks in the 3-4 hours prior to a long training run can serve as part of your pre-race fueling strategy (and it is a strategy you can use on race day). 

If you’re not sure which protein powder is right for you and your training plan, Gainful can help. Gainful creates a customized protein supplement based on your body type, dietary needs, activity level and fitness goals — “running a marathon” included. You just take a quiz to find your personalized blend of high-quality ingredients, and Gainful takes care of the rest. Whether you’re gluten-free, lactose-free or anything in between, Gainful can help you integrate a personalized protein powder (and a personalized hydration formula) into your marathon training program. There’s a protein powder for every type of runner. 

Even better: As part of your Gainful subscription, you’ll also have access to a Registered Dietitian, who can answer any questions you may have about your training regimen or fueling your body for a marathon. 

Gainful wants to join you in your marathon training.