How many calories do you need to run a marathon?

October 31, 2025 •

4 min read

Typically, a runner burns around 100 calories per mile during a marathon, totaling over 2,600 calories. However, the exact number of how many calories do you need to run a marathon varies widely depending on individual factors like weight, running speed, and metabolism.

Quick Summary

Calorie expenditure in a marathon is unique to each runner, affected by weight, pace, and efficiency. Effective fueling requires careful planning and consistent intake during the race to avoid energy depletion.

Key Points

General Estimate: Expect to burn at least 2,600 calories during a marathon, based on the average of 100 calories per mile.
Personalized Calculation: Factors like your body weight and running speed significantly influence your exact calorie expenditure.
Race-Day Fueling: Aim to consume 200–300 calories (30–60g of carbs) per hour during the race to prevent 'hitting the wall'.
Pre-Race Carb-Loading: Maximize your glycogen stores by increasing your intake of complex carbohydrates in the 24-48 hours before the race.
Trial Your Fueling: Never try a new fueling or hydration product on race day; practice and perfect your strategy during training runs.
Replenish and Recover: Immediately after the race, consume a mix of carbohydrates and protein to replenish glycogen and aid muscle repair.

The Calorie Equation: More Than a Simple Number

While the average calorie burn for a marathon is often stated as exceeding 2,600, this is only a general estimate. Personal energy requirements are determined by a more complex equation with several key variables. Understanding these factors is the first step toward creating an effective fueling strategy to prevent 'hitting the wall,' which is the state of total glycogen depletion.

Factors Influencing Calorie Burn

Body Weight: Heavier runners expend more energy to move their body over the 26.2-mile distance. For example, a 185-pound person burns significantly more calories than a 125-pound person running at the same speed.
Running Pace: Increased speed results in higher caloric expenditure per hour. Higher intensity requires more energy, leading to a greater hourly calorie expenditure. However, this is balanced by a shorter race time, so total calories might not change as dramatically as the hourly rate.
Running Efficiency: Experienced runners often develop better running economy, meaning they use less energy to maintain a given pace. Beginners, conversely, may burn more calories due to less efficient mechanics.
Metabolism: Basal metabolic rate (BMR) and individual metabolic function play a role. Some people naturally burn calories faster than others.

Calculating Your Marathon Calorie Needs

For a more personalized estimate, you can move beyond the standard 100-calories-per-mile rule. One method is to use a MET (Metabolic Equivalent of Task) formula, which factors in your weight and speed. Alternatively, a simpler calculation involves using your weight and duration.

General Calculation Guide

Calorie Burn: Use the average of 100 calories per mile, which for a marathon (26.2 miles) equates to 2,620 calories burned. Use this as a baseline.
Total Calorie Needs: For endurance athletes, daily calorie intake can range from 2,000 to 7,000 calories, depending on training volume and intensity. A runner doing 2-3 hours of intense running per day may need 25-30 calories per pound of bodyweight.

Example: A 150-pound (68kg) runner in heavy training might need 4,500 calories a day to maintain weight and fuel workouts.

Fueling Strategy: Ingesting Calories During the Race

It is crucial that all the calories burned are not replaced during the race. The body's absorption capacity is limited, typically allowing for 60-90 grams of carbohydrates (240-360 calories) per hour. The goal is not to match expenditure but to consume enough fuel to keep glycogen stores from running out completely.

Marathon Fueling Options Compared


Fuel Type	Calories (Approx.)	Carbohydrates (Approx.)	Speed of Absorption	Best Used For
Energy Gels	80-120 kcal per gel	20-30g per gel	Fast	Quick, concentrated energy boost during the run
Sports Drinks	80-120 kcal per 16 oz	20-30g per 16 oz	Moderate	Hydration and fuel replacement, less dense than gels
Energy Chews/Blocks	30-50 kcal per block	8-12g per block	Moderate	Easily portioned, sustained energy source
Whole Foods (e.g., Banana)	100-110 kcal per banana	25-30g per banana	Slower	Steady energy, but can cause stomach upset in some runners

How to Avoid 'Hitting the Wall'

To prevent bonking, start consuming calories early in the race. Experts recommend starting within the first 30-60 minutes and continuing to consume fuel every 30-40 minutes. Practicing this during long training runs is essential to allow your digestive system to adapt and to find what works best for you.

Race-Day Nutrition: The Full Picture

Fueling a marathon is not just about what you consume during the race; it's a multi-day process.

Pre-Race Fueling

Carb-Loading: In the 24-48 hours before the race, increase your intake of complex, easily digestible carbohydrates like pasta, rice, and whole-grain bread to maximize your muscle glycogen stores.
Race-Day Breakfast: A meal 2-3 hours before the race is crucial. Focus on carbohydrates and a small amount of protein, while avoiding high-fiber and high-fat foods that can cause GI distress. Porridge, bagels with peanut butter, or bananas are classic options.

Post-Race Recovery

Immediately after finishing, your body needs to start repairing and recovering. Within 30 minutes, consume 200-300 calories of carbohydrates and protein to replenish glycogen and repair muscle tissue. A 3:1 or 4:1 carb-to-protein ratio is often recommended. Good options include chocolate milk, a recovery shake, or a banana with peanut butter.

Conclusion: Personalize Your Approach

There is no single answer to how many calories do you need to run a marathon. The average of 2,600 is a good reference, but needs are influenced by physiology, weight, and pace. Successful marathon runners practice and refine their fueling strategy during training, ensuring they start the race with fully loaded glycogen stores and replenish consistently on the course to avoid energy depletion and finish strong. For more guidance on race-day hydration, read additional expert advice at Runner's World.

Disclaimer: For personalized medical and nutrition advice, consult with a registered dietitian or sports medicine professional.

Frequently Asked Questions

Your body has a limited capacity to absorb carbohydrates and process energy during intense exercise. Trying to ingest thousands of calories mid-race would overwhelm your digestive system and cause significant gastrointestinal distress.

Hitting the wall, or 'bonking,' is a sudden and severe loss of energy that occurs when your body's glycogen stores are nearly or fully depleted. It results in extreme fatigue and can make it difficult or impossible to continue running.

Most runners aim for 30-60 grams of carbohydrates per hour. With many gels containing 20-30 grams of carbs, this means consuming one or two gels per hour, in addition to other sources. Experienced runners may consume up to 90g of carbs per hour.

Yes, carb-loading is recommended for endurance events like marathons. It involves consuming high amounts of carbohydrates in the days before the race to maximize your muscle and liver glycogen stores, giving you more energy at the start line.

Have a high-carbohydrate, low-fiber, and low-fat meal 2-3 hours before the race. Good options include oatmeal, a plain bagel with a little peanut butter, or bananas. Avoid anything new to prevent stomach upset.

Experts recommend consuming a snack with a mix of carbohydrates and protein within 30 minutes of finishing. This helps replenish depleted glycogen stores and aids in muscle repair. After this immediate window, continue consuming nutritious meals.

Experts advise against very low-carb or keto diets for distance runners. Carbohydrates are the body's primary and most efficient fuel source for endurance running, and restricting them can significantly impact performance and recovery.

Yes, your running pace directly affects calorie burn. Running at a faster pace requires more energy and burns more calories per minute than running slower. However, this is partially offset by finishing the race faster, so the total calories burned is more influenced by weight and total duration.