A diet for ultra marathoners requires more than just long miles; it requires a well-planned approach that supports endurance, recovery, and overall health if you want to smash your A-goal. As an evidence-based sports dietitian, I’ve helped many ultra-endurance athletes meet the unique nutritional demands of this sport. This guide covers everything from fueling to hydration and micronutrient needs, so you can fuel smarter and run stronger.

Why Nutrition is So Important for Ultra Marathoners

Ultra marathoners face distinct physical challenges that set them apart from other endurance athletes. Running for hours—sometimes days—puts stress on the body’s energy stores, muscles, and hydration levels. A well-planned diet can make all the difference in your performance, helping you:

• Sustain Energy: Long-duration runs require a steady source of fuel to avoid energy crashes.
  
• Speed Up Recovery: Proper nutrition helps repair muscle damage and replenishes glycogen stores.
  
• Prevent Injury: A balanced diet with enough vitamins, minerals, and macronutrients supports joint health and reduces the risk of overuse injuries.
  
• Boost Immune Health: Intense training can weaken the immune system, so nutrient-dense foods can help maintain it.

Carbohydrates: The Primary Fuel Source for Ultra Marathoners

Carbohydrates are crucial for ultra marathoners like you because they are the most efficient source of energy during endurance activities. 

Here’s how to structure carb intake:

Types of Carbohydrates

• Complex Carbohydrates: These include whole grains like oats, quinoa, and sweet potatoes. They provide a slower energy release, making them perfect for meals leading up to long runs.
  
• Simple Carbohydrates: Foods like bananas, dates, and sports drinks offer quick energy, making them ideal during long runs and for immediate pre-run snacks.

Carbohydrate Intake Guidelines

• Daily Intake: Aim for about 5-7 grams of carbohydrates per kilogram of body weight on training days, increasing to 8-12 grams per kilogram during peak training.
  
• Pre-Run Fueling: Eat a carb-rich meal about 3-4 hours before a long run. Examples include oatmeal with berries or a bagel with peanut butter and honey.
  
• During the Run: Consume 30-60 grams of carbs per hour during runs over 90 minutes. Gels, chews, and dried fruits are great options.
  
• Post-Run Recovery: To replenish glycogen, aim for a 3:1 ratio of carbs to protein within 30 minutes post-run. A smoothie with banana, berries, and protein powder works well.

Protein for Recovery and Muscle Repair

Protein helps ultra marathoners repair muscle damage, reduce soreness, and support recovery between training sessions.

Key Protein Tips for Ultra Marathoners

• Daily Intake: Aim for 1.2-2.0 grams of protein per kilogram of body weight daily, depending on training load.
  
• Post-Run Recovery: Include 15-25 grams of protein in your post-run meal to kickstart muscle repair.
  
• Timing Matters: Spread protein intake throughout the day to support muscle recovery and reduce soreness.

High-Protein Food Options

• Eggs: A complete protein source with essential amino acids.
  
• Greek Yogurt: High in protein and contains probiotics for gut health.
  
• Lentils and Beans: Plant-based options packed with fiber, iron, and protein.
  
• Lean Meats and Fish: Chicken, turkey, and salmon are protein-rich options that support recovery.

Healthy Fats for Long-Lasting Energy

Fats are essential for ultra marathoners, especially during longer runs when glycogen stores begin to deplete. They provide a slow-burning energy source that supports endurance.

How to Include Healthy Fats in Your Diet

• Avocados: High in monounsaturated fats and potassium, beneficial for muscle function.
  
• Nuts and Seeds: Almonds, walnuts, and chia seeds offer omega-3s and fiber, which aid in digestion and inflammation reduction.
  
• Olive Oil: Anti-inflammatory and heart-healthy, ideal for cooking or drizzling over vegetables.
  
• Nut Butters: Calorie-dense and portable, nut butters are a great snack during ultra events.

When to Consume Fats

• Before Long Runs: Include a small amount of fat, like almond butter on toast, in your pre-run meal to support satiety and provide long-lasting energy.
  
• During Training: If your run lasts several hours, foods with healthy fats like energy bars made from nuts and seeds can help maintain energy levels without causing gastrointestinal discomfort.

Hydration and Electrolytes: The Key to Endurance

Ultra marathoners often run in varying weather conditions, making hydration and electrolyte balance essential.

Hydration Tips for Ultra Marathoners

• Pre-Hydration: Start hydrating the day before a long run by drinking plenty of water and including hydrating foods like watermelon and cucumber.
  
• During the Run: Aim to drink about 400-800 ml of water per hour, depending on sweat rate and temperature. Add electrolytes to your water if you’re sweating heavily.
  
• Post-Run Hydration: Rehydrate with water and an electrolyte drink to replenish lost sodium, potassium, and magnesium.

Key Electrolytes and Food Sources

• Sodium: Found in pickles, olives, and salted snacks. Replenishes what’s lost in sweat.
  
• Potassium: Bananas, potatoes, and coconut water are high in potassium, which aids in muscle function.
  
• Magnesium: Found in leafy greens, nuts, and seeds, magnesium helps prevent cramps.

Micronutrients for Immune Health and Recovery

Long training hours can deplete your body’s micronutrient reserves. Incorporate these essential vitamins and minerals to support endurance and recovery:

Key Micronutrients for Ultra Marathoners

• Iron: Crucial for oxygen transport to muscles. Sources include spinach, lean meats, and fortified cereals.
  
• Vitamin D: Supports bone health and immunity. Get it from sun exposure, fortified dairy, or supplements if needed.
  
• Calcium: Essential for bone health, found in dairy, fortified plant milks, and leafy greens.
  
• B Vitamins: Aid in energy metabolism. Sources include eggs, whole grains, and legumes.

Micronutrient Boosting Foods

• Spinach: Rich in iron, calcium, and magnesium.
  
• Oranges and Citrus Fruits: High in vitamin C, which supports immune health and aids iron absorption.
  
• Nuts and Seeds: Almonds, chia seeds, and flaxseeds are packed with micronutrients like magnesium, iron, and vitamin E.

Common Nutrition Mistakes and How to Avoid Them

Proper nutrition can be tricky, especially when balancing intense training demands. Here are some common pitfalls and tips to stay on track:

• Underestimating Caloric Needs: Ultra marathoners require more calories than typical endurance athletes. Under-fueling can lead to energy crashes and fatigue.
  
• Skipping Electrolytes: Don’t rely on water alone. Add electrolyte-rich foods or drinks to maintain sodium and potassium levels.
  
• Ignoring Recovery Nutrition: Delaying post-run nutrition can hinder recovery. Aim for a protein-rich snack within 30 minutes.
  
• Trying New Foods on Race Day: Stick to a tried-and-tested diet on race day to avoid GI issues.

Proper nutrition is the foundation of ultra running performance. By planning your diet to include carbohydrates, protein, healthy fats, and essential micronutrients, you can optimize endurance, recovery, and overall health. Experiment with these tips during training to find what works best for you.

Get the Endurance Sports Nutrition Guide Bundle today for more tips on how to manage your nutrition as an ultra marathoner.