Are Marshmallows Good for Running? Your Complete Fueling Guide

December 7, 2025 •

5 min read

According to anecdotal evidence from some ultrarunners, marshmallows have been used as a cheap and effective source of carbohydrates during long endurance events. But are marshmallows good for running, and are they a viable alternative to traditional sports nutrition products? The answer depends on the timing, dosage, and type of run.

Quick Summary

Marshmallows provide simple sugars for rapid energy during long runs but lack other vital nutrients and can cause digestive issues. They are an unorthodox but potentially useful fuel source for endurance athletes who tolerate them well, but moderation and strategic timing are key.

Key Points

Marshmallows are a high-glycemic food: They provide simple sugars for rapid energy but should only be used strategically during long runs.
Not a complete fueling solution: Marshmallows lack essential electrolytes and other nutrients needed for sustained performance, unlike commercial sports products.
Risk of GI distress: The high concentration of simple sugars can cause bloating and cramping in some runners, especially if consumed in large quantities.
Reserve for during a run: Avoid eating marshmallows as a pre-run snack to prevent a potential sugar crash. They are best for efforts over 90 minutes.
Prioritize practice over race day experiments: Always test any new fueling strategy, including using marshmallows, during training to assess your body's tolerance.
Pair with electrolytes: If using marshmallows, it is critical to supplement with an electrolyte-rich sports drink or chew to avoid mineral imbalance.

The Science of Sugar for Endurance Running

During prolonged exercise lasting more than 90 minutes, your body relies heavily on stored carbohydrates, or glycogen, for energy. As these stores deplete, performance suffers, a phenomenon known as "hitting the wall." To prevent this, endurance runners ingest simple carbohydrates during their activity to provide an easily absorbed fuel source.

Marshmallows are primarily composed of simple sugars like sucrose and corn syrup, making them a dense source of carbohydrates. This composition means they can be broken down and absorbed quickly, providing a rapid energy boost. For some runners, this makes them an attractive, no-frills alternative to expensive gels and chews. However, this simplicity is also their biggest drawback, as they contain virtually no electrolytes, vitamins, or minerals that traditional sports nutrition is fortified with.

Strategic Timing and Consumption

The timing of your carbohydrate intake is critical. Eating simple sugars right before a short run can cause a rapid spike and subsequent crash in blood sugar, leading to premature fatigue. Marshmallows should be reserved for fueling during a long, sustained effort, not as a pre-run snack. Here is a guide on how to integrate them safely:

During a run: For efforts over 90 minutes, aim to consume 30-60 grams of carbohydrates per hour. With one marshmallow containing roughly 6 grams of carbohydrates, you would need to consume 5 to 10 marshmallows per hour. Start with a small amount and test your tolerance during training. Dehydrated marshmallows might be a more convenient option for mid-run consumption.
Practice, Don't Guess: Never try a new fueling strategy on race day. Use your long training runs to experiment with marshmallows. Test how they affect your energy levels and digestive system. Some runners may experience GI distress from the pure sugar content.
Hydration is Key: Because marshmallows are pure sugar, they do not replace the need for electrolytes. Be sure to use a sports drink or an electrolyte tablet with your water to maintain proper hydration and mineral balance.

Potential Downsides and Considerations

While the appeal of using simple, inexpensive fuel is understandable, marshmallows come with several potential downsides for runners:

Digestive Discomfort: A high concentration of simple sugars can draw water into your intestines, leading to bloating, cramping, and other gastrointestinal issues. The chewiness can also be difficult to manage while breathing heavily during a run.
Nutrient Deficiency: Unlike fortified sports products, marshmallows lack the sodium, potassium, and other electrolytes lost through sweat. Relying solely on them could lead to an electrolyte imbalance, impacting muscle function and overall performance.
Taste Fatigue: The intense sweetness can become cloying over time, leading to taste fatigue and an aversion to your fuel source during a long event. This can be a major hurdle for athletes in ultramarathons and other prolonged races.
Inconvenience: Eating a single marshmallow on the run is easy, but consuming enough to meet hourly carbohydrate needs (up to 10 marshmallows) is less practical than a single gel or chew. The stickiness also presents a handling challenge.

Comparison Table: Marshmallows vs. Energy Gels


Feature	Marshmallows	Energy Gels
Primary Carbohydrate	Simple sugars (sucrose, corn syrup)	Simple sugars (maltodextrin, fructose, glucose)
Energy Absorption	Very fast due to simple sugars	Very fast, some with advanced absorption methods
Nutrient Content	Negligible electrolytes, vitamins, or minerals	Often fortified with key electrolytes (sodium, potassium)
Cost per Serving	Very low	Moderate to high
Taste	Sweet, often becomes cloying over time	Wide variety of flavors, often less intense
Convenience	Can be sticky and require frequent consumption	Single-serving packets are easy to carry and consume
Digestive Risk	Potential for GI distress from pure sugar	Lower risk with tailored carb combinations

Conclusion: A Novelty, Not a Staple

While marshmallows can serve as an emergency or occasional source of quick carbohydrates for experienced endurance runners, they are not a complete fueling solution. Their high glycemic index and lack of electrolytes make them an unconventional choice, best suited for athletes who have tested them thoroughly and understand their limitations. For most runners, especially beginners, traditional sports nutrition products are the safer, more reliable option. They provide a balanced mix of carbohydrates and electrolytes and are specifically designed for easy digestion and consumption during intense activity. The best approach is to experiment with a variety of fuel sources during your training to see what works best for your body, saving the marshmallow for a celebratory treat rather than a primary fuel source.

When to reach for a marshmallow

As an emergency boost: A few marshmallows can provide a quick jolt of sugar if you suddenly feel your energy flagging toward the end of a long run.
On very long, slow efforts: During an ultramarathon or an exceptionally long training run, the novelty of a different texture and flavor can provide a psychological lift when taste fatigue sets in.
For low-intensity, longer runs: On days when you're not pushing the pace, a few marshmallows can provide simple carbs without the digestive burden of a high-intensity effort.
During a carb-loading phase (for some): As part of a carbohydrate-loading strategy before a race, consuming low-fiber, high-carb foods like marshmallows can help maximize glycogen stores, though it's best to test this in training.

Ultimately, while the internet lore of marshmallows as running fuel is fun, smart runners prioritize a well-rounded nutrition strategy over a singular, unconventional food item.

A Final Word of Advice

If you choose to experiment with marshmallows for running, remember to hydrate consistently with an electrolyte-containing beverage. This prevents the primary pitfalls of using pure sugar for fuel. Listen to your body and adjust your fueling plan based on its feedback.

The best alternatives to marshmallows

For runners seeking a balanced, reliable fuel source, many alternatives offer a better nutritional profile and easier digestion:

Energy Gels: Provide a concentrated dose of carbohydrates and often include electrolytes, designed for rapid absorption.
Energy Chews: Similar to gels but in a solid, chewable format, with a variety of carb blends and electrolytes.
Dried Fruit: A more natural source of simple sugars, along with some fiber and nutrients. Dates and raisins are popular choices.
Sports Drinks: Combine carbohydrates and electrolytes in liquid form for easy intake and hydration.
Homemade Rice Cakes: A whole-food option for solid carbs during longer efforts, often made with rice, sugar, and sometimes savory additions.

Frequently Asked Questions

Marshmallows can provide simple carbohydrates for energy during long runs, but they cannot fully replace energy gels. Gels are often fortified with electrolytes, which marshmallows lack, and are designed for easier digestion during strenuous activity.

Before a run, it is best to have a mix of simple and complex carbs one to two hours beforehand for sustained energy. Simple carbs like those in marshmallows are best used during a long run for an immediate energy boost, not before.

To carry marshmallows on a run, you can use a small plastic bag or a resealable container to prevent them from getting sticky. Some runners find dehydrated mini-marshmallows to be a more convenient option for mid-run consumption.

Eating marshmallows can cause a sugar crash if consumed at the wrong time, such as right before a run. However, when consumed strategically during a sustained, long run, the body utilizes the sugar quickly and the effect is more of a rapid energy boost than a crash.

The primary benefit of marshmallows for runners is a readily available source of simple carbohydrates for quick energy during exercise. They offer no significant nutritional benefits like vitamins, minerals, or fiber.

Compared to alternatives like energy gels, chews, or dried fruit, marshmallows are cheaper and offer a change in texture. However, they lack electrolytes and other nutrients found in most sports-specific nutrition products and can be harder to consume and digest.

New runners should start with conventional, tested sports nutrition products like gels, chews, or sports drinks. Using marshmallows is an unconventional method best reserved for experienced endurance athletes who have a solid understanding of their fueling needs and gastrointestinal sensitivities.