Marathon Fueling Guide

Marathons are challenging endeavors and demand the most out of your body, both mentally and physically. Regardless of your fitness level or the speeds you run, you will be using significant amounts of energy during a marathon. This energy comes from endogenous sources fats and carbohydrates stored in your body and/or exogenous sources (food/liquid consumed while you run). However, of these two primary sources of energy used, carbohydrates are the most limited, while fats (in the context of running a marathon) are not. When carbohydrates, in the form of glycogen (in the skeletal muscle and liver) and glucose (in the blood) are low, both mental acuity and running performance will decrease. This typically results in “hitting the wall” and bonking. To prevent this, you need to supply your body with the energy to sustain such a strenuous effort over multiple hours. The best way to do this is to fuel by consuming carbohydrates during your marathon. 

We have developed a simple guide with a series of considerations to help you develop a fueling plan before and during your marathon so that you can have the best marathon experience possible and not have your fueling and nutrition plan be a point of failure during your race. 

Preparing to Fuel Your Marathon 

• Training Your Gut

• It is ideal that during your training, you use products containing carbohydrates and consume the amount of carbohydrates that you plan to use during your marathon. Gut training is important to preventing GI distress during your marathon, and it also allows you to practice the act of consuming fuel during your runs so that you are familiar with the sensations associated with it. Furthermore, practicing fueling during your training allows you to test nutrition plans and products that work well for you. 

• There are always different ways you can mix and match Carbs Fuel Products to achieve your target carbohydrate intake. Here is an example progression you can follow to train your gut using the Original 25 gram (100 calories) and 50 gram (200 calories)  gels:

1. 1. 1. We recommend those new to fueling to consume a Carbs Fuel Original 25 gram Energy Gel every 45 minutes. 

      2. You can then increase this amount to a Carbs Fuel Original 25 gram Energy Gel every 30 minutes. 

      3. Then progress to one Carbs Fuel Original 50 gram Energy Gel every 45 minutes.

      4. Eventually alternate between one Carbs Fuel Original 50 gram Energy Gel and one Carbs Fuel Original 25 gram Energy Gel every 30 minutes.

• Fueling Using Fluid

• • Another way to fuel is by using the Original Sport Drink Mix. Each serving has 75 grams of carbohydrates (300 calories) and 500 milligrams of sodium. Mixing the sports drink mix with water into a flask can be an effective all-in-one solution to allow you to fuel as well as replenish the sodium and fluid loss through sweating. This is also a great option if you do not like the consistency of a gel or find the serving size of a gel overwhelming. The Original Sport Drink Mix allows you further flexibility in your fueling plan. 

• Carbohydrate Loading

• Carbohydrate loading is a method to boost your body’s carbohydrate stores in your skeletal muscle before a strenuous event. This can improve performance, increase endurance, and prevent early carbohydrate depletion.

• The general recommendation for carbohydrate loading is to increase the amount of carbohydrate you consume in your diet in the 2-3 days leading up to your marathon.

• A great place to start is to consume 8 grams of carbohydrates per kilogram of body weight. Otherwise, we recommend consuming 10-12 grams of carbohydrates per kilogram of body weight. 

• Meals Before Your Race

• The meal prior to your race is meant to top off your glycogen stores in your liver, which are depleted overnight while you sleep. Ideally, this meal is eaten within a few hours before your race starts and is easily digestible with low amounts of fiber, fats, and protein. For example, the meal can be easily digested carbohydrates such as rice, toast with jelly, pancakes, and waffles.

• If you typically consume caffeine, continue to consume your usual amount in the days leading up and the morning prior to the race; we suggest not changing your routine (i.e. more or less caffeine) before your race as this may introduce unwanted variables, potentially resulting in a bad day or poor performance.

As always, these are starting recommendations to begin developing your nutrition plan to perform your best on race day. We always suggest speaking with a sports nutritionist or registered dietitian if you are looking for a personalized approach to this process. 

Fueling During Your Marathon

As mentioned before, your body will be using a significant amount of carbohydrates during your marathon. While it is true that your body will be using fats during your run, the fat stores are essentially “unlimited” for the duration of your marathon. This is not true for your carbohydrate stores in your body. Depending on the intensities, skeletal muscle glycogen stores are sufficient to sustain approximately 2 hours of exercise. When your muscle glycogen stores run low, you will begin to feel low on energy and eventually “hit the wall” if you do not consume any or insufficient amount of carbohydrates. With this in mind, your primary fuel source should be carbohydrates and not fat or protein. Using fueling options that are carbohydrate dense will allow your body to quickly absorb the carbohydrate it needs without delays in absorption that can come with consuming fuel sources that are dense with fiber, fats, or proteins. 

Keep in mind that whether you’re running 2:30 or 4:30, you will still be burning a lot of energy in the form of carbohydrates. In other words, if you are a 4:30 marathoner, even though you are not running as fast as the 2:30 marathoner, you are running for two more hours! This means you will still be using a substantial amount of carbohydrates simply because you are running for a longer total amount of time. This is what we recommend when it comes to fueling your marathon: 

• Fueling based on milage:

• New to fueling

• One Original 25 gram gel every 3-4 miles. Or..

• Sip on one serving of Sport Drink Mix (75 gram carbohydrates) throughout 8-12 miles.

• Experienced with fueling

• One Original 50 gram gel every 5 miles. Or…

• One Original 50 gram gel and one Original 25 gram gel alternating every 5 miles. Or..

• Sip on one serving of Sport Drink Mix (75 gram carbohydrates) throughout 5-8 miles.

• Fueling based on time: 

• New to fueling

• One Original 25 gram gel every 30-45 minutes. Or…

• Sip on one serving of Sport Drink Mix (75 gram carbohydrates) throughout 90-135 minutes.

• Experienced with fueling

• One Original 50 gram gel every 30 minutes. Or…

• One Original 50 gram gel and one Original 25 gram gel alternating every 30 minutes. Or…

• Sip on one serving of Sport Drink Mix (75 gram carbohydrates) throughout 30-45 minutes.

• Caffeine considerations

• Caffeine works most effectively when you are fatigued. We suggest consuming caffeine in the middle or final quarter of your marathon when you will be experiencing the most fatigue. The Caffeinated Original gel is an option that packs 50 grams of carbohydrates with 100 milligrams of caffeine (a big cup of coffee) and will surely bring you out of a slump. As always, make sure that you test caffeinated products in your training so that you know how your body will respond. If you are interested in reading more, check out our caffeine blog.

• Temperature considerations

• Weather should be an important consideration for everyone, but especially for those who are on course longer as the exposure to hot and sunny conditions means that your body may be losing more water and electrolytes than those who are on course for a shorter period of time. 

• If it is a hot and/or humid marathon with significant sun exposure…

• Emphasize/make it a point to drink water at the aid stations; don’t skip water if it is a hot day!

• However, be careful of overconsuming water without adequate intake of sodium. As you sweat, you lose both water and electrolytes (primarily sodium). If you are only replenishing the water lost from your body, you will dilute the sodium in your body leading to low sodium in your blood (hyponatremia). This can have severe impacts on your performance and health. So, make sure to include sodium intake in your fueling and hydration plan.

• Adding sodium to your fueling plan can help with replenishing your sodium lost through your sweat. Consider replacing one Original 50 gram gel with a Salted Original 50 gram gel.

A Note on Hydration and Fueling

Hydration and fueling are sometimes thought of independently. However, fueling well with minimal to no GI distress can be impacted by your hydration status. The more dehydrated you are, the greater the chance of experiencing GI distress, especially if you are new to fueling with higher densities of carbohydrates. The movement of water into and out of the gut is part of the nutrient absorption process. If you are dehydrated, this process is challenged leading to a greater chance of GI distress. Additionally, less absolute blood flow to the gut (due to dehydration) can also exacerbate this issue. So, ensure that you are consuming adequate amounts of fluid at aid stations or have a plan that will keep you well-hydrated. 

Final Thoughts

As always, we recommend experimenting and trying different fueling strategies while keeping in mind potential weather influences on your plan and preparing for those situations as well. Don’t let nutrition be the point of failure or downfall after training and putting in so much hard work for your marathon. If you have further questions on how to use Carbs Fuel products during your marathon, please reach out: info@carbsfuel.com