The Best Diet for Long Distance Runners: Fueling for Performance

October 20, 2025 •

4 min read

According to sports nutrition research, muscle glycogen is the primary energy source for endurance exercise, and depleted stores are directly linked to fatigue. This makes implementing the best diet for long distance runners a crucial strategy for maximizing performance and endurance, whether you're tackling a marathon or an ultramarathon.

Quick Summary

This guide provides a comprehensive breakdown of the nutritional strategies essential for long distance runners. It details the critical roles of carbohydrates, protein, and fats, and outlines effective plans for fueling before, during, and after runs. Practical advice on hydration, electrolyte balance, and avoiding common dietary mistakes is also covered to help runners optimize their performance and recovery.

Key Points

Prioritize Carbohydrates: Carbs are the primary fuel source for endurance running, so intake should be aligned with training volume to keep glycogen stores full and prevent fatigue.
Time Your Intake: Fuel 2-4 hours before a run with complex carbs, use simple carbs during runs over 60-90 minutes, and consume a carb-protein mix within 30-60 minutes post-run for optimal recovery.
Emphasize Quality Protein: Consistent protein intake from lean sources like fish, poultry, eggs, and legumes supports muscle repair and adaptation.
Stay Hydrated and Balanced: Maintain daily hydration and use electrolytes for runs over an hour or in hot conditions. Avoid over-drinking plain water, which can lead to dangerously low sodium levels.
Train Your Gut: Practice your fueling and hydration strategy during training runs to avoid stomach issues on race day and optimize your body's ability to process fuel while running.
Don't Fear Healthy Fats: Incorporate healthy fats from sources like avocado and nuts for sustained energy and vitamin absorption, but avoid high-fat meals right before a run.
Include Micronutrients: Ensure adequate intake of iron, calcium, and antioxidants from a varied diet to support bone health, immune function, and overall performance.

Macronutrients: The Foundation of a Runner's Diet

A balanced intake of carbohydrates, protein, and fats is vital for long-distance runners to sustain energy, repair muscles, and maintain health.

Carbohydrates: The Runner's Primary Fuel

Carbohydrates are the body's main energy source during running, stored as glycogen. Sufficient glycogen prevents 'hitting the wall' in events over 90 minutes. A runner's carbohydrate needs are high and depend on training intensity and volume. Complex carbs provide steady energy for daily meals, while simple carbs offer quick energy before, during, or immediately after a run for rapid replenishment.

Examples:

Complex: Oatmeal, whole-grain pasta, brown rice, sweet potatoes.
Simple: Sports drinks, gels, bananas, white bread.

Protein: For Muscle Repair and Recovery

Protein is crucial for repairing muscle damage from intense exercise. Aim for 20-30 grams of protein per meal or snack, spread throughout the day.

Lean protein sources:

Fish, poultry, lean meats
Eggs, dairy
Lentils, chickpeas, tofu

Fats: A Concentrated Energy Source

Healthy fats provide sustained energy for low-to-moderate intensity exercise and aid vitamin absorption. Focus on unsaturated fats, avoiding high-fat meals right before a run.

Healthy fat options:

Avocado, nuts, seeds
Olive oil, fatty fish

Timing Your Nutrition: Before, During, and After

Strategic timing of food intake is key and varies with run duration and intensity.

Pre-Run Fueling

2-4 hours before: A carbohydrate-focused meal with moderate protein and low fiber/fat. Example: Bagel with peanut butter and a banana.
30-60 minutes before: A small, easily digestible carb snack. Example: Banana or sports drink.

Fueling During a Run

For runs over 60-90 minutes, consume carbohydrates to prevent energy depletion. Aim for 30-60 grams of carbs per hour, potentially more for ultra-endurance. Sources include gels, chews, or sports drinks. Practice your strategy during training to avoid stomach issues.

Post-Run Recovery

Refuel within 30-60 minutes after a hard run with a 3:1 or 4:1 carbohydrate-to-protein ratio. Examples: Chocolate milk or a protein smoothie.

Hydration and Electrolytes: Non-Negotiable Elements

Dehydration harms performance and can cause fatigue and cramps. Drink water consistently, checking urine color. For runs over an hour, sports drinks or electrolytes replace lost salts. Avoid over-hydration with plain water, which can lead to hyponatremia; drink to thirst and ensure electrolyte balance.

Comparison Table: Common Runner's Diet Myths vs. Facts


Feature	Myth	Fact
Carb-Loading	Massive pasta night before race is enough.	Starts 2-3 days prior with increased carbs and reduced mileage for events > 90 mins. Test in training.
Protein	Shakes needed after every run.	Post-run meal with 3:1 carb-protein ratio is effective; spread protein intake.
Fat	All fat is bad.	Healthy fats provide sustained energy and aid vitamin absorption; include in daily meals, not right before running.
Hydration	Drink maximum water before a race.	Over-drinking can cause hyponatremia. Drink consistently leading up to race day and follow a tested strategy.
Fueling Strategy	Only matters on race day.	Consistent practice in training is essential for performance and avoiding stomach issues during race.

Training Your Gut to Tolerate Race Fuel

Just like physical training, your digestive system needs to adapt to race-day fueling. Practice your planned nutrition and hydration during training runs. This helps your gut become more efficient at digesting food while running, reducing the risk of gastrointestinal issues like cramping or diarrhea during a race. Experiment with different types of fuel to find what works best.

The Role of Micronutrients

Vitamins and minerals are vital for runner health and performance. Key micronutrients include:

Iron: Carries oxygen to muscles; runners are at risk of deficiency. Sources: lean meat, lentils, beans.
Calcium & Vitamin D: Crucial for bone health, reducing stress fracture risk. Sources: dairy, fortified plant milks.
Antioxidants: Combat training-induced oxidative stress. Sources: fruits, vegetables.
Electrolytes (Sodium, Potassium, Magnesium): Lost in sweat; crucial for muscle function and fluid balance. Replenish with sports drinks or salty snacks.

A Sample Day of Eating for an Endurance Runner

Breakfast (Pre-run): Oatmeal with milk, banana, nuts.
During a Long Run: Gels and sports drink every 30-45 minutes.
Post-Run Snack (within 30-60 min): Chocolate milk or a smoothie.
Lunch: Salad with grilled chicken, quinoa, vegetables.
Afternoon Snack: Apple slices with peanut butter.
Dinner: Whole-grain pasta with lean meat/lentil sauce, side salad.
Evening Snack: Cottage cheese with fruit.

Conclusion: Personalization is Paramount

The best diet for long distance runners is built on nutrient-dense carbohydrates, adequate protein, healthy fats, and proper hydration with electrolytes. However, success hinges on personalization and practice. Test fueling strategies during training, listen to your body, and adjust intake based on training volume to optimize performance and reach your goals.

Visit Sports Dietitians Australia for more detailed sports nutrition guidelines.

Frequently Asked Questions

Two to four hours before a long run, consume a carbohydrate-rich, low-fiber, and low-fat meal that you have practiced with during training. Examples include oatmeal with a banana, a bagel with peanut butter, or toast with honey.

Yes, for any run lasting over 90 minutes, including a marathon, you need to consume carbohydrates during the race to prevent muscle glycogen depletion and maintain energy levels. Aim for 30-60 grams of carbohydrates per hour.

Consume a snack or meal with a 3:1 or 4:1 carbohydrate-to-protein ratio within 30-60 minutes after finishing. This replenishes glycogen stores and aids muscle repair. Options include chocolate milk, a smoothie, or a turkey sandwich.

Carb-loading is beneficial for endurance events lasting over 90 minutes. It involves increasing your carbohydrate intake 2-3 days before the race to maximize muscle glycogen stores, which can improve performance and endurance.

Hydration is extremely important. Losing just 1% of body weight in fluid can decrease performance. Drink water consistently, and for runs over an hour, use sports drinks or electrolytes to replace lost salts.

Most experts do not recommend a very low-carb or ketogenic diet for long distance runners, as carbohydrates are the primary fuel for endurance. Inadequate carbohydrate intake can negatively impact performance, recovery, and overall health.

Vegan runners can get sufficient protein from sources like legumes (beans, lentils), tofu, soy products, nuts, seeds, and whole grains. Combining these sources throughout the day ensures intake of all essential amino acids.

Gastrointestinal distress can be caused by various factors, including the type and timing of food and fluid intake. High-fiber, high-fat, or spicy foods before a run can be problematic. Test all fueling strategies during training to find what works for you and avoid issues on race day.