Should I eat peanut butter before a marathon? The Ultimate Runner's Guide

October 8, 2025 •

5 min read

According to a study cited by Elo Health, a small amount of peanut butter can be part of a pre-run meal when paired with a carbohydrate source at least 90 minutes to two hours beforehand. The question, should I eat peanut butter before a marathon? is nuanced, with the answer hinging on preparation, timing, and personal tolerance.

Quick Summary

This guide explores the benefits and risks of consuming peanut butter before a marathon. It emphasizes the importance of proper timing, small portion sizes, and combining it with carbohydrates for sustained energy. Successful fueling depends on testing a nutrition strategy during long training runs to ensure digestive comfort.

Key Points

Timing is Everything: Eat a small portion of peanut butter 1.5 to 2 hours before your marathon to allow for proper digestion.
Portion Control: Limit your serving to 1-2 tablespoons to avoid weighing down your stomach with too much fat.
Pair with Carbs: Always combine peanut butter with an easily digestible carbohydrate like a bagel, banana, or white toast for optimal energy absorption.
Test During Training: Practice your peanut butter fueling strategy during your long training runs to test your tolerance and perfect your routine.
Sustained Energy: The combination of fats and protein in peanut butter provides a steady release of energy that helps prevent mid-race crashes.
Choose Natural: Opt for natural peanut butter with minimal ingredients to reduce the risk of GI distress from added sugars or oils.
Know Your Limits: If you experience stomach upset during training, consider reducing the amount or avoiding peanut butter on race day entirely.

The question of whether or not to include peanut butter in your pre-marathon meal is one many runners face. It's a convenient, energy-dense food, but its high fat content also makes it a slow-digesting fuel source. For a successful race, the key lies not in a simple 'yes' or 'no', but in understanding the science of sports nutrition and applying it to your individual needs.

The Nutritional Benefits of Peanut Butter for Runners

Peanut butter, particularly natural versions with minimal added ingredients, offers several nutritional advantages for long-distance runners. It is a source of healthy monounsaturated and polyunsaturated fats, which play a beneficial role in an athlete's diet, including providing energy and essential fatty acids.

Sustained Energy: The combination of fats, protein, and carbohydrates helps stabilize blood sugar levels, providing a more sustained release of energy compared to simple sugars. This can help stave off hunger and prevent energy crashes during long runs.
Nutrient-Dense: Peanut butter contains more than 30 essential vitamins and minerals, including vitamin E (an antioxidant), magnesium (important for muscle function), and niacin (helps convert food to energy).
Satiety: The protein and fat content promote a feeling of fullness for a longer period, which can be useful on race day.

Potential Downsides and Risks on Race Day

Despite its benefits, peanut butter is not without risks, especially if consumed incorrectly before a high-intensity, long-duration event like a marathon. The primary concern is its high fat and fiber content, which can lead to digestive issues.

Slow Digestion: Fat and protein take significantly longer to digest than carbohydrates. Eating too much peanut butter or eating it too close to the race start can leave you with a feeling of heaviness or cause gastrointestinal (GI) distress, including cramps, bloating, and nausea.
Displacing Carbs: Marathon fueling is fundamentally about maximizing glycogen stores through carbohydrates. Over-relying on peanut butter can fill you up without providing the readily available energy your muscles need for the race, potentially compromising your carb-loading strategy.
Calorie Density: While beneficial for runners with high energy needs, the high calorie density means it's easy to consume too many calories from peanut butter, especially if you are not accustomed to it.

Timing and Portion Control are Critical

The most important factor for incorporating peanut butter into your race-day nutrition plan is timing. A small portion, typically 1-2 tablespoons, should be consumed at least 90 minutes to two hours before the race, always paired with a fast-digesting carbohydrate.

Race Week Peanut Butter Strategy


Phase	Timing Relative to Race	Rationale for Peanut Butter	Example Meal
Carb-Loading	2-3 Days Before	Can be included in moderate amounts to provide healthy fats and satiety, but prioritize carbs.	Whole-wheat toast with a thin layer of peanut butter and banana slices.
Night Before	12+ Hours Before	Best to avoid high-fat meals. A small amount is okay if your gut is accustomed to it, but stick to simple, tested foods.	Light pasta with marinara sauce and a lean protein source is a safer bet.
Race Morning	1.5-2 Hours Before	A small serving (1-2 tbsp) with simple carbs to top off glycogen and provide sustained energy.	Plain bagel or white toast with a small amount of peanut butter and jam or honey.

How to Test and Incorporate Peanut Butter

Never introduce a new food on race day. Your pre-race fueling strategy should be practiced and perfected during your long training runs. Here are some steps to ensure peanut butter works for you:

Test Early and Often: During your marathon training cycle, experiment with different amounts of peanut butter and various food pairings before your longest runs. Start with a small amount and observe how your stomach reacts.
Choose Natural Peanut Butter: Opt for natural versions with minimal ingredients (just peanuts and maybe salt) and no added sugars or oils. The added ingredients in processed peanut butter can sometimes increase the risk of GI issues.
Combine with Carbs: Peanut butter should not be eaten alone as a pre-race fuel. Its high fat content will slow carbohydrate absorption. Pair it with simple, easy-to-digest carbs like a banana, plain bagel, or white toast.
Listen to Your Body: Every runner's digestive system is different. Pay close attention to how you feel during your test runs. If you experience any discomfort, it might be a sign to reduce the portion size or relegate peanut butter to a post-race recovery food.

Conclusion

So, should you eat peanut butter before a marathon? The answer is a qualified yes, but only with strict conditions. A small amount, combined with an easily digestible carbohydrate and consumed at least 90 minutes before the race, can be an excellent source of sustained energy. However, it's not a replacement for proper carb-loading and should be carefully tested during your long training runs. For many runners, a small smear on a bagel with jam is the perfect compromise, providing flavor and a steady release of energy without causing digestive upset. Ultimately, the best race-day nutrition is a strategy that has been practiced and proven to work for you. For more insights on optimal fueling, consider checking out resources like Mayo Clinic Health System's article on healthy fats for runners.

Race Morning Peanut Butter Checklist

Timing: Consume at least 90-120 minutes before the race starts.
Portion Size: Stick to a small amount, no more than 1-2 tablespoons.
Pairing: Always combine with a simple carbohydrate like a plain bagel, white toast, or banana.
Product Choice: Use natural peanut butter with minimal added ingredients.
Test in Training: Never try this for the first time on race day. Practice during long training runs.
Listen to Your Gut: Pay attention to how your body reacts and adjust accordingly.

Recipes for Pre-Marathon Fueling

Classic Peanut Butter & Banana Toast

Ingredients: 1 slice white bread or a plain bagel, 1-2 tablespoons natural peanut butter, 1/2 banana sliced.
Instructions: Toast the bread or bagel. Spread with peanut butter and top with banana slices. Easy, delicious, and easy to digest when timed properly.

Pre-Race Peanut Butter Smoothie

Ingredients: 1/2 banana, 1 tablespoon peanut butter, 1/2 cup almond milk, 1-2 dates (for extra carbs).
Instructions: Blend all ingredients until smooth. A great option if you prefer liquid fuel that's easy to digest.

Peanut Butter & Jam Sandwich

Ingredients: 2 slices white bread, 1-2 tablespoons natural peanut butter, 1 tablespoon of your favorite jam (choose one with minimal additives).
Instructions: Combine the ingredients for a classic, carb-heavy pre-race snack that tastes great and fuels you well.

Frequently Asked Questions

Yes, a peanut butter and jelly sandwich can be an excellent pre-marathon meal. The bread and jelly provide the quick-absorbing carbohydrates needed for energy, while a small amount of peanut butter adds healthy fat and protein for sustained energy release. Be sure to test this during training and allow enough time for digestion, typically 90 minutes to two hours before the race.

Peanut butter is beneficial for pre-marathon fueling due to its energy-dense content, healthy fats, and protein. These components provide a slower, more sustained release of energy compared to simple carbs alone, helping to maintain stable blood sugar levels during a long endurance event.

A small portion of 1 to 2 tablespoons is recommended for a pre-race meal. This amount offers nutritional benefits without causing digestive discomfort from too much fat, and should always be paired with a carbohydrate source.

Consuming too much peanut butter too close to a marathon can lead to GI distress, including bloating, cramping, and nausea. Its high fat content makes it slow to digest, which can be problematic during intense exercise.

It is best to eat peanut butter at least 90 minutes to two hours before your race. This allows ample time for digestion and prevents feelings of heaviness or discomfort during the run.

Natural peanut butter, which typically contains only peanuts and salt, is a better choice. It avoids the added sugars, oils, and additives found in many regular peanut butter brands that can increase the risk of digestive issues on race day.

While some runners use peanut butter sandwiches or spreads during ultras for a flavor change, it is generally not recommended for a typical marathon. Its slow digestion can cause GI issues mid-run. Energy gels, chews, and sports drinks are more easily digestible and absorbed for quick fuel.

If peanut butter causes you digestive issues, alternatives include small amounts of other nut butters (like almond butter), or focusing on other easily digestible carb sources like oatmeal, bagels with honey, or bananas.