Nutrition Diet: What is the best food to eat while running a marathon?

October 3, 2025 •

5 min read

According to sports nutrition experts, your body's stored carbohydrates (glycogen) can only fuel 60–90 minutes of high-intensity running, making mid-race fueling crucial for endurance athletes. Knowing what is the best food to eat while running a marathon can mean the difference between a strong finish and hitting the dreaded wall.

Quick Summary

Running a marathon requires a smart fueling strategy to replenish depleted glycogen stores. The ideal approach involves consuming 30–90 grams of fast-digesting carbohydrates per hour, along with proper hydration and electrolytes. Runners can choose between commercial products like gels and chews or real food options, all tested during training to prevent gastrointestinal issues on race day.

Key Points

Start Early: Begin consuming carbohydrates within the first 30–45 minutes of the race, not when you feel fatigued.
Replenish Carbs: Aim for 30–90 grams of carbohydrates per hour, using a combination of sources for maximum absorption.
Stay Hydrated: Don't rely on plain water alone; supplement with electrolytes to replace sodium lost through sweat and prevent hyponatremia.
Practice in Training: Never test a new food, gel, or drink on race day. Practice your entire fueling and hydration plan during your long training runs.
Choose Your Fuel: Select between commercial energy gels/chews for quick, measured energy or real foods like bananas or dried fruit for a more natural approach, based on what your stomach tolerates best.
Use Caffeine Strategically: If you tolerate it, use caffeinated gels in the latter half of the race for a mental and physical boost, but test doses in training first.

As you push through the miles of a marathon, your body's energy needs become a primary concern. Even with perfect pre-race carbohydrate loading, your glycogen stores will eventually deplete, leading to a significant drop in performance known as 'hitting the wall'. To avoid this, and to maintain a consistent pace, a well-planned nutrition strategy during the race is essential. The cornerstone of this plan is understanding that your muscles primarily rely on carbohydrates for energy during high-intensity exercise. As the race progresses, your body becomes less efficient at digesting food, so the type of fuel and timing of consumption are critical for sustained energy and comfort.

The Science of Mid-Race Fuelling

For runs lasting longer than 90 minutes, your body needs an external source of carbohydrates to top up blood glucose levels and delay fatigue. The optimal hourly intake of carbohydrates for endurance athletes is a widely researched topic, with general recommendations ranging from 30 to 90 grams per hour, depending on intensity and training level. Elite athletes consuming the higher end of this range typically use dual-source formulations that combine different types of sugars (like glucose and fructose) to maximize absorption, as the body can process more carbohydrates per hour when they come from multiple sources.

Glucose: The body's primary and most easily utilized energy source, ideal for quick energy delivery.
Fructose: Absorbed via a different pathway, allowing the body to process a higher total volume of carbohydrates when combined with glucose.
Maltodextrin: A glucose polymer often used in sports nutrition for its rapid absorption and less sweet taste.

Popular Fuel Choices: Gels, Chews, and Drinks

Sports nutrition products are scientifically formulated to deliver fast-acting, easily digestible carbohydrates directly to your system. They are popular for their convenience and specific design for on-the-go consumption, but it's vital to test them during training.

Energy Gels: These are concentrated packets of carbohydrates. Isotonic gels, like SiS GO Isotonic Gels, are designed to be consumed without extra water, minimizing the risk of stomach upset. Other brands like Maurten and GU offer varying consistencies, carbohydrate sources, and added electrolytes or caffeine.
Energy Chews: Gummy-like chews provide a measured dose of carbs and are a good alternative for runners who dislike the consistency of gels. They often come in multiple pieces, allowing for more controlled dosing.
Sports Drinks: These offer a dual benefit of carbohydrates and electrolytes in a single liquid form, helping with both hydration and fueling. However, depending on the concentration, they may still require supplementary water to avoid GI issues.

Going Natural: Real Food Options

For some runners, commercial sports products can cause stomach issues or simply be unappealing. Real food, especially low-fiber, high-carbohydrate options, can be a great alternative, provided they are practiced during training.

Bananas: A classic running food, bananas offer easily digestible carbohydrates and a good dose of potassium, an important electrolyte.
Dried Fruit: Raisins, dates, and apricots are a compact source of sugar and calories. Dates, in particular, are favored for their high carbohydrate content.
Pretzels: Salted pretzels provide simple carbohydrates and sodium, helping to replenish electrolytes lost through sweat.
Boiled Potatoes: A favorite for ultra-runners, boiled and salted potatoes offer a savory alternative to sweet gels and chews and are easy on the stomach.

Fueling Strategy: A Comparison

Choosing between commercial products and real food depends on individual preferences and needs. Here is a comparison to help inform your decision.


Feature	Commercial Sports Products	Real Food Options
Carb Availability	Specifically measured and formulated for fast absorption.	Natural mix of sugars, often with slower digestion due to fiber.
Absorption Speed	Designed for quick digestion and glucose delivery.	Varies based on food type; typically slower than engineered products.
Convenience	Compact and easy to carry in small packs or flasks.	Can be bulkier; may require more preparation and carrying space.
Cost	Can be more expensive per serving compared to basic real foods.	Generally more cost-effective, using readily available ingredients.
GI Tolerance	Formulated to minimize distress, but individual sensitivity varies. Isotonic and hydrogel options are often gentler.	May cause fewer issues for sensitive stomachs, but fiber content can be a factor.
Added Benefits	Often include specific electrolytes, caffeine, or amino acids.	Provides natural vitamins and minerals.

Hydration and Electrolytes: The Critical Partner

While carbohydrates fuel your muscles, hydration keeps your body functioning optimally. During a marathon, you lose significant amounts of fluid and electrolytes, primarily sodium, through sweat. Relying on plain water alone can dilute your body's sodium levels and potentially lead to hyponatremia, a dangerous condition.

Replenish lost sodium by sipping electrolyte drinks, dissolving electrolyte tablets, or consuming salt capsules.
The amount of fluid and electrolytes you need is highly individual and depends on factors like your sweat rate, body weight, pace, and weather conditions.
Practice your hydration strategy during training by measuring your sweat rate and experimenting with different electrolyte products.

Tips for a Successful Fuelling Strategy

Train as you Race: Never try a new product or food on race day. Your training runs, especially your longest ones, are the perfect time to test your fueling and hydration plan.
Start Fuelling Early: Don't wait until you feel tired. Begin consuming carbohydrates within the first 30–45 minutes of the race and continue at regular intervals, typically every 20–45 minutes. Set a timer on your watch to avoid forgetting.
Manage Caffeine: If you plan to use caffeinated gels for a late-race boost, practice with them beforehand. Be mindful of your tolerance and avoid excessive intake, which can cause jitters or stomach upset.
Address GI Issues: If you experience stomach problems mid-race, try slowing your pace and taking a few sips of plain water with a salt capsule. This can help rebalance your system and aid absorption.
Tapering and Carb Loading: In the days leading up to the race, decrease your training intensity and increase your carbohydrate intake to top off glycogen stores. Reduce fiber and fat to ease digestion.

Conclusion: Practice Your Plan for Peak Performance

Ultimately, there is no single 'best food' for every runner. The ideal race-day nutrition is a personalized strategy developed through trial and error during your training block. While commercial gels and chews offer scientifically formulated, rapidly absorbed energy, real foods like bananas and dried fruit can be equally effective for those with sensitive stomachs or a preference for natural options. The key is to practice your fueling plan consistently in training, paying close attention to both carbohydrate intake and proper hydration. By doing so, you'll cross the finish line feeling strong, well-fueled, and accomplished.

This article is for informational purposes only. Consult a healthcare professional or registered dietitian for personalized advice.

Frequently Asked Questions

The number of gels depends on your pace and carbohydrate needs. Most runners aim for 30–90 grams of carbs per hour, with many standard gels containing around 25 grams of carbs. For a four-hour marathon, this could mean 8–12 gels, depending on the carb content and how often you fuel.

Neither is inherently better; it's a matter of personal preference. Chews can be easier to portion and chew, while gels are often quicker to consume. Some find the taste and texture of chews more appealing. It is important to test both during training to see what works best for you.

Yes, many runners successfully use real food like bananas, dried fruit, or salted potatoes. The key is to choose low-fiber options that are easily digestible and practice with them during your long training runs to ensure they don't cause stomach upset.

To avoid 'the wall,' consistently replenish your glycogen stores by taking in carbohydrates regularly throughout the race, starting early (within the first 30-45 minutes). Practice your fueling strategy in training, and ensure you are taking in enough fluids and electrolytes.

The best sports drink contains both carbohydrates and electrolytes, especially sodium, to fuel your muscles and replace what is lost in sweat. Many race courses provide specific brands, so training with those can be beneficial.

Caffeine can help reduce your perception of fatigue during endurance events. If you tolerate caffeine well, you can strategically use a caffeinated gel in the later stages of the race. However, caffeine sensitivity varies greatly, so it is crucial to test it during training.

Mid-race stomach issues are often caused by dehydration, electrolyte imbalance, or consuming too many carbs too quickly. Slow down, take in some plain water or an electrolyte capsule, and try to consume fuel in smaller, more frequent doses. Practicing 'gut training' during workouts can also help.