Marathon Nutrition Guide: Complete Fueling Strategy for Training and Race Day

Why Marathon Nutrition Makes or Breaks Your Race

You've put in months of training. You've logged hundreds of miles. You're physically ready.

Then mile 20 hits, and your legs feel like concrete. Your pace plummets. You're bonking.

The culprit? Not your training—it's your fueling strategy.

The truth: Marathon nutrition is as important as your training plan. Your body can store about 90-120 minutes of glycogen. A marathon takes 3-6 hours. The math doesn't work without proper fueling.

This guide covers:

• Daily nutrition during marathon training
• Pre-race fueling (week before and race morning)
• In-race nutrition strategy (what, when, how much)
• Post-race recovery nutrition
• Common mistakes and how to avoid them

Understanding Marathon Energy Demands

What Your Body Burns During a Marathon

Energy sources your body uses:

1. Glycogen (stored carbs): Primary fuel, limited supply (90-120 min worth)
2. Fat: Unlimited supply, but slower to convert to energy
3. Protein: Emergency backup (you don't want to get here)

The problem: Your glycogen stores deplete around mile 18-20. If you haven't fueled properly, you hit "the wall"—sudden, severe fatigue where your pace crashes.

The solution: Train your gut to process fuel while running, and execute a race-day fueling plan.

Daily Nutrition During Marathon Training

Macronutrient Breakdown for Marathoners

Carbohydrates: 55-65% of daily calories

• Why: Primary fuel for running
• Sources: Whole grains, rice, pasta, potatoes, fruits, oats
• Timing: Especially important pre-run and post-run

Protein: 15-20% of daily calories

• Why: Muscle repair and recovery
• Sources: Lean meats, fish, eggs, legumes, Greek yogurt, tofu
• Target: 0.5-0.7g per pound of body weight (75-105g for a 150lb runner)

Fats: 20-30% of daily calories

• Why: Essential for hormone production, vitamin absorption, sustained energy
• Sources: Avocados, nuts, olive oil, fatty fish, seeds

Fueling Around Training Runs

Pre-Run Nutrition

Easy runs (< 60 min):

• Minimal pre-fueling needed
• Coffee + banana or small snack if running in AM

Long runs (90+ min):

• 2-3 hours before: Carb-rich meal with moderate protein, low fat/fiber
• Examples:
  • Oatmeal with banana and honey
  • Bagel with peanut butter
  • Toast with jam and scrambled eggs
  • Rice with chicken

30 min before: Optional small snack (banana, energy bar, gel)

During-Run Fueling (Training Runs)

Runs under 90 minutes: Water only, no fuel needed

Runs 90-120 minutes:

• Start fueling at 45-60 min
• 30-45g carbs per hour
• Practice with gels, chews, or sports drinks

Runs 2+ hours:

• 60g carbs per hour (some athletes tolerate up to 90g)
• Start fueling at 30-45 min
• Fuel every 30-45 min throughout

Critical: Use long runs to practice your race-day fueling strategy

Post-Run Nutrition

Within 30 minutes: Carbs + protein (3:1 or 4:1 ratio)

• Chocolate milk
• Smoothie with banana, protein powder, berries
• Recovery shake
• Bagel with nut butter

Within 2 hours: Full meal with carbs, protein, vegetables

Hydration During Training

Daily baseline: Half your body weight in ounces (150lb = 75oz daily)

Pre-run: 16-20oz in the 2 hours before running

During run:

• 4-8oz every 15-20 min
• More in hot/humid conditions
• Include electrolytes on runs 60+ min

Post-run: 16-24oz per pound of body weight lost (weigh yourself before/after)

Hydration check: Urine should be pale yellow (not clear, not dark)

Pre-Race Nutrition Strategy

The Week Before Your Marathon

3-7 Days Out: Normal Eating + Hydration Focus

Don't: Drastically change your diet Do:

• Maintain regular eating patterns
• Increase hydration gradually
• Reduce fiber slightly (prevent GI issues)
• Cut alcohol (dehydrating, disrupts sleep)

2-3 Days Out: Carb Loading

What it is: Increasing carb intake to maximize glycogen stores

How much: Increase to 65-70% of calories from carbs (8-12g per kg body weight)

What to eat:

• White rice, pasta, bread (lower fiber for easier digestion)
• Potatoes, sweet potatoes
• Bananas, applesauce
• Pretzels, bagels
• Sports drinks

What to reduce:

• Fiber (can cause GI distress)
• Fats (slows digestion)
• Protein (no need to increase)
• New/unfamiliar foods

Sample carb-loading day:

• Breakfast: Pancakes with syrup, banana, orange juice
• Snack: Bagel with honey
• Lunch: White rice bowl with chicken, low-fiber veggies
• Snack: Pretzels, sports drink
• Dinner: Pasta with marinara, white bread
• Snack: Applesauce, crackers

Myth busting: Carb loading doesn't mean eating massive amounts. Increase carbs by reducing fats/protein, not by overeating.

Race Morning Nutrition

Timing: Eat 2-3 hours before race start

What to eat: Familiar, easily digestible, carb-rich

• 1-4g carbs per kg body weight (150-600 calories for most runners)
• Minimal fat, fiber, protein

Classic race morning meals:

• Bagel with honey or jam
• Oatmeal with banana and maple syrup
• White toast with peanut butter and banana
• Rice cakes with almond butter
• Granola bar + banana

Coffee: If you normally drink it, have it (aids performance). If not, don't start now.

30-45 min before start: Optional gel or small snack

Hydration: 16-20oz water, finish 45 min before start

In-Race Fueling Strategy

The Golden Rule

Never try anything new on race day. Every gel, chew, and drink should be tested in training.

How Much to Fuel

Target carb intake: 30-60g per hour (most runners), up to 90g for advanced athletes

Why it matters:

• Too little = bonking, hitting the wall
• Too much = GI distress, cramping, nausea

What 30-60g looks like:

• 1 gel = ~25g carbs
• 1 serving chews (6 pieces) = ~24g
• 16oz sports drink = ~14-28g
• 1 energy bar = ~20-40g

Fueling Timeline

Mile 0-5: Water only

• Your glycogen stores are full
• Stomach is still adjusting to running
• Sip water at aid stations

Mile 6-10: Start fueling

• First gel or chews around mile 6-7
• Alternate water and sports drink at aid stations
• Establish your fueling rhythm

Mile 11-20: Maintain consistent fueling

• Gel or chews every 4-5 miles (45-60 min)
• Water or sports drink at every aid station
• Don't skip fueling even if you feel good

Mile 21-26.2: Push through

• Final gel at mile 21-22
• Water at every remaining aid station
• Mental focus—your fueling work is done

Sample Race Fueling Plans

Plan A: Gels + Water (Simple)

• Mile 7: Gel + water
• Mile 12: Gel + water
• Mile 17: Gel + water
• Mile 22: Gel + water
• Every other aid station: Water
• Total: ~100g carbs

Plan B: Gels + Sports Drink (Moderate)

• Mile 6: Gel
• Mile 11: Gel
• Mile 16: Gel
• Mile 21: Gel
• Every aid station: Sports drink
• Total: ~120g carbs

Plan C: Mixed Sources (Advanced)

• Mile 5: Sports drink
• Mile 8: Energy chews
• Mile 12: Gel
• Mile 16: Energy chews
• Mile 20: Gel
• Every aid station: Alternating water/sports drink
• Total: ~140g carbs

Hydration During the Race

General rule: 4-8oz every 15-20 min (roughly every aid station)

Don't: Chug large amounts at once Do: Small, frequent sips

Hot/humid conditions: Increase intake, include electrolytes

Signs you're dehydrated:

• Dark urine
• Dizziness
• Muscle cramps
• Headache

Signs you're overhydrated (rare but dangerous):

• Bloating
• Nausea
• Confusion
• Swelling in hands/feet

Electrolytes: The Missing Piece

Why Electrolytes Matter

What they are: Sodium, potassium, magnesium, calcium

Why you need them:

• Muscle contraction
• Nerve function
• Fluid balance
• Prevent cramping

Sweat loss: Runners lose 500-1,000mg sodium per hour through sweat

How to Get Electrolytes

Sports drinks: 100-200mg sodium per 8oz

Gels: Some contain 30-100mg sodium (check labels)

Salt tablets: 200-400mg per tablet

Electrolyte drink mixes: 300-500mg per serving

Real food (later miles if your stomach can handle):

• Pretzels
• Salted potatoes
• Pickle juice

Recommendation: Aim for 300-600mg sodium per hour in addition to carbs

Post-Race Recovery Nutrition

Immediate Post-Race (0-30 min)

Priority: Start recovery process

What to consume:

• 20-30g protein
• 60-90g carbs
• 16-24oz fluid

Easy options:

• Chocolate milk (classic for a reason)
• Recovery shake
• Banana + protein bar
• Sports drink + protein shake

Why it matters: 30-minute window for optimal muscle glycogen replenishment

Next 24 Hours

Focus: Replenish glycogen, repair muscle damage, rehydrate

Meals: High-quality carbs + protein

• Breakfast: Pancakes, eggs, fruit
• Lunch: Rice bowl with protein and veggies
• Dinner: Pasta with meat sauce, salad
• Snacks: Greek yogurt, fruit, nuts, smoothies

Hydration: Continue drinking—urine should be pale yellow

Anti-inflammatory foods:

• Berries
• Leafy greens
• Fatty fish (salmon)
• Turmeric
• Tart cherry juice (reduces muscle soreness)

Common Nutrition Mistakes

1. Not Practicing Fueling in Training

Mistake: "I'll figure out fueling on race day"

Why it fails: Your gut needs training too. New fuel sources can cause cramping, nausea, diarrhea.

Fix: Practice exact race-day fueling during long runs (16+ miles)

2. Trying New Foods Race Week

Mistake: Carb loading with unfamiliar foods, trying a new pre-race breakfast

Why it fails: GI distress, unpredictable reactions

Fix: Stick to tried-and-true foods. Race week is not the time to experiment.

3. Underfueling in Training

Mistake: Not fueling on long runs to "save calories" or "train the body to burn fat"

Why it fails:

• Increases injury risk
• Impairs recovery
• Doesn't replicate race conditions
• Can lead to RED-S (Relative Energy Deficiency in Sport)

Fix: Fuel all runs over 90 minutes

4. Overdrinking or Underdrinking

Mistake: Chugging water at every aid station OR skipping hydration entirely

Why it fails:

• Overdrinking = hyponatremia (dangerous)
• Underdrinking = dehydration, performance decline

Fix: Stick to 4-8oz every 15-20 min, adjust for conditions

5. Ignoring Electrolytes

Mistake: Only drinking water during marathon

Why it fails: Dilutes blood sodium, increases cramp risk

Fix: Consume 300-600mg sodium/hour via sports drinks, gels, or salt tablets

6. Eating Too Much Fat/Fiber Pre-Race

Mistake: Big breakfast with bacon, eggs, avocado, and whole grain toast

Why it fails: Slow digestion can cause GI distress during race

Fix: Keep pre-race meals high-carb, low-fat, low-fiber

7. Skipping Post-Race Nutrition

Mistake: "I'm too tired/nauseous to eat"

Why it fails: Delays recovery, increases soreness, extends fatigue

Fix: Force down something simple (chocolate milk, smoothie) within 30 min

Special Considerations

Running in Heat

• Increase fluid intake by 25-50%
• Prioritize electrolytes (higher sweat losses)
• Consider ice/cold sponges at aid stations
• Pre-hydrate aggressively

Running in Cold

• Still need to fuel (same energy demands)
• Hydration still critical (cold air is dry)
• Warm pre-race meal may be comforting
• Easier to carry gels (less sticky)

Vegetarian/Vegan Marathoners

Protein sources:

• Legumes, tofu, tempeh, seitan
• Quinoa, nutritional yeast
• Plant-based protein powders

Iron: More critical for plant-based athletes

• Dark leafy greens, lentils, fortified cereals
• Pair with vitamin C for absorption

B12: Supplement required for vegans

GI-Sensitive Runners

Strategies:

• Reduce fiber 48 hours before race
• Avoid dairy if lactose intolerant
• Test multiple fuel brands (some are gentler)
• Consider real food (bananas, rice cakes) instead of gels
• Stay upright (don't bend over) when consuming fuel

Fueling Products: What Works

Energy Gels

Pros: Portable, easy to carry, predictable carbs Cons: Some find texture/taste unpleasant

Popular brands: GU, Maurten, SIS, Huma, Spring Energy

Tip: Take with water, not sports drink (too much sugar at once)

Energy Chews

Pros: Easy to consume, less messy than gels Cons: Requires chewing (harder when breathing hard)

Popular brands: Clif Bloks, GU Chews, Skratch Chews

Sports Drinks

Pros: Hydration + carbs + electrolytes in one Cons: Heavier to carry, aid stations may not have your preferred brand

Popular brands: Gatorade Endurance, Maurten, Skratch Labs, Tailwind

Real Food

Pros: Some runners tolerate better than gels Cons: Harder to digest, less portable

Options: Bananas, dates, rice cakes with honey, boiled potatoes with salt

DIY Fuel

Homemade sports drink:

• 32oz water
• 2-3 tbsp maple syrup or honey
• 1/4 tsp salt
• Squeeze of lemon

How kovaa Optimizes Marathon Fueling

Marathon training isn't just about mileage—it's about preparing your entire system, including your gut.

kovaa helps by:

• Fueling reminders during long runs at optimal intervals
• Nutrition guidance tailored to your training plan
• Tracking what works so you refine your race-day strategy
• Recovery metrics (HRV, sleep) to ensure you're fueling adequately
• Race-day fueling calculator based on your goal pace and conditions

The platform ensures your fueling strategy is as dialed in as your training plan.

Your Marathon Nutrition Checklist

Training Phase

• Practice fueling on all runs 90+ minutes
• Test multiple gel/chew brands
• Establish hydration needs (weigh before/after long runs)
• Identify any GI triggers
• Finalize your race fueling plan

Race Week

• Carb load 2-3 days before (not the night before)
• Reduce fiber and fats
• Stay hydrated consistently
• Pack race-day fuel (gels, chews, etc.)
• Plan race morning meal

Race Morning

• Eat 2-3 hours before start
• Sip water, finish 45 min before
• Coffee if you normally drink it
• Optional gel 30 min before start

During Race

• Start fueling at mile 6-8
• Consume 30-60g carbs per hour
• Fuel every 45-60 min
• Sip water/sports drink at every aid station
• Don't skip fueling even when feeling good

Post-Race

• Consume carbs + protein within 30 min
• Rehydrate aggressively
• Eat full meal within 2 hours
• Continue recovery nutrition for 24-48 hours

Final Thoughts

Your training gets you to the start line. Your fueling gets you to the finish.

Marathon nutrition isn't complicated, but it requires:

• Planning: Know what you'll eat and when
• Practice: Test everything in training
• Execution: Stick to your plan even when adrenaline says otherwise

The runners who nail their fueling:

• Avoid bonking
• Maintain pace through mile 20+
• Finish strong
• Recover faster

The runners who wing it:

• Hit the wall
• Suffer through the final miles
• Miss their goal time
• Take longer to recover

Respect the distance. Fuel properly. Finish strong.

Download kovaa for personalized marathon training plans with integrated fueling guidance that adapts to your progress.