The Complete Half Marathon Fueling Guide: What to Eat Before, During & After Your Run
If you’re training for a half marathon, you already know how much time, energy, and discipline it requires. The early mornings, the long runs on weekends, the stretching, the strength training — you’re doing all the right things.
But there’s one piece most runners overlook, and it’s often the deciding factor between a strong race and a miserable one: your fueling.
As a Running Dietitian and Run Coach, I work with hundreds of runners every year who are training harder than ever…but not fueling anywhere near enough to sustain their performance. And for most of them, the issues aren’t lack of commitment, it’s confusion. “Am I eating enough carbs?” “Should I carb load?” “Do I really need gels?” “Why do I bonk so early?”
Whether you’re stepping up to the start line for the first time or aiming for a brand-new PR, this guide will walk you through exactly what your body needs before, during, and after your half marathon so you can run strong, avoid GI issues, and recover like an athlete, even if you don’t feel like one yet.
And if you want personalized guidance tailored to your running schedule, your body, and your race goals, you can apply to work with me inside my 1:1 program, Nutrition for Runners.
Why Half Marathon Fueling Matters More Than You Realize
Most runners assume that if they train enough, their race day performance will take care of itself. But here’s the reality:
Your body can only store enough glycogen (your main energy source for running) to fuel you for 60–90 minutes at best.
A half marathon takes most runners 90–150 minutes, sometimes more. That means unless you’re fueling in a structured way leading up to your race, and during it, your body simply cannot keep up.
This is why mile 8, 9, or 10 often feels like hitting a brick wall. Fatigue skyrockets. Legs feel like concrete. Pace falls apart. Brain fog hits. You start questioning if you misjudged your fitness.
But here’s the thing…It’s not your fitness. It’s your fueling. And the good news is that fueling is fixable.
With the right plan, you will feel more energized, more confident, and more in control of your pacing, and that alone can completely transform your race-day experience.
What to Eat the Week Before Your Half Marathon
The week before your race sets the stage for everything. Think of it as laying the foundation for steady energy and consistent pacing. Your goal isn’t to “carb load like crazy” or eat huge amounts of food — it’s to gradually increase carbs, keep things simple, and avoid anything that disrupts digestion.
Carbs: Your Primary Fuel
Throughout the week, focus on including carbs at every meal and most snacks. You don’t need to suddenly triple your portions, but small additions go a long way.
Examples of easy carb add-ons:
A second slice of toast at breakfast
An extra half cup of rice or potatoes at lunch
A granola bar or fruit between meals
A sports drink with electrolytes
Aim for 5–7g of carbs per kg of body weight, but if numbers feel overwhelming, just focus on steadily increasing your intake.
Protein: Support Repair and Recovery
You don’t need more protein than usual, but you do need enough. Most runners feel best with 20–30g per meal to keep muscles supported as training peaks.
Hydration: Start Early
Proper hydration is one of the biggest predictors of race-day performance.
Instead of chugging water the night before your race, begin focusing on hydration throughout the entire week.
A simple goal: Pale yellow urine + electrolytes at least once per day.
What to Eat the Day Before Your Race
The day before your half marathon is all about keeping things easy, predictable, and gentle on your digestive system.
This is not the day to experiment with a new restaurant, new foods, or anything overly high in fiber or fat.
What Dinner Should Look Like
Aim for a plate that is:
Carb-forward
Lower in fiber
Moderate in protein
Low in fat
Examples of a pre-race dinner:
White rice with chicken and a simple sauce
Pasta with marinara and lean meat
Potatoes with grilled salmon
Rice noodles with tofu or shrimp
Avoid anything fried, creamy, spicy, or full of raw vegetables.
If your stomach tends to be sensitive, keep portions moderate and consider eating dinner a bit earlier than usual to give yourself more time to digest.
Race Morning: What to Eat Before You Run
Race morning fueling can make or break your performance.
Your goal is to top up your glycogen without upsetting your stomach — which is why practice matters. Ideally, you’ve tested your race breakfast during training.
3–4 Hours Before the Race
Aim for 75–100g of carbs + 15–25g protein.
Some great options:
A bagel with peanut butter + banana
Oatmeal topped with honey + Greek yogurt
Toast with jam + a protein shake
This meal is your main fuel source for the first half of the race.
1 Hour Before
This is where runners miss an easy win. Adding 20–30g of fast carbs boosts blood glucose and helps you start your race strong.
Good options for pre-race fuel:
A gel
A few chews
Applesauce pouch
Right Before You Start (10–15 Minutes)
Taking a gel right before you start is incredibly effective. It gives your body immediate, readily available fuel and delays fatigue.
Fueling During the Half Marathon
This is the part most runners resist, but also the part that makes the biggest difference.
You need 30–60g of carbs per hour to maintain your pace.
For a typical 2-hour race, that means 3–4 gels total.
Example Race Fueling Plan
If you’re running around 2 hours:
Start: 1 gel
30 min: 1 gel
60 min: 1 gel
90 min: 1 gel
If gels upset your stomach, use:
Chews
Sports drink
Waffles
Maple syrup packets
The most important part: don’t wait until you feel tired. Fuel early, and fuel regularly.
Hydration During the Race
Sip small amounts (~4 oz) every 15 minutes or whenever you hit aid stations.
Take electrolytes if the weather is hot or humid.
Avoid chugging water, as this can lead to cramps and GI distress.
What to Eat After Your Half Marathon
Recovery begins the moment you cross the finish line. To support your muscles, reduce soreness, and restore glycogen, you’ll want to eat within 30–45 minutes after your race.
Aim for:
20–30g protein
40–80g carbs
Fluids + electrolytes
Examples:
A smoothie
Chocolate milk and a banana
A bagel and eggs
A rice bowl with chicken or tofu
Your goal is to start the recovery process early so you can bounce back quickly.
Common Fueling Mistakes That Sabotage Half Marathon Performance
If you’ve ever struggled with:
Early race fatigue
Stomach problems
Inconsistent pacing
Cramps
Brain fog
Hitting the wall
Here are some common mistakes that might be sabotaging your performance:
Skipping carbs during the race
Not fueling early enough
Eating too little the week before
Trying new food the night before or morning of the race
Underhydrating
Ignoring electrolytes
Not practicing fueling during training
Most runners don’t have a training problem. They have a fueling problem — and once that piece is fixed, everything else feels easier.
Ready to Run Your Strongest Half Marathon Yet?
The earlier you practice your fueling strategy, the better you’ll perform on race day. Start this week — pick one long run and practice your pre-run meal, your mid-run fueling, and your hydration strategy.
Your PR is built on consistency, confidence, and energy, and fueling gives you all three.
Want a Personalized Half Marathon Fueling Plan?
If you’re tired of guessing what to eat, wondering how many gels you need, or feeling unsure about your nutrition — I can help!
Inside Nutrition for Runners, my 1:1 program, I create a customized, easy-to-follow fueling plan based on:
Your mileage
Your pace
Your training history
Your GI tolerance
Your race goals
I help you learn exactly what to eat, when to eat it, and how to fuel your long runs and race day with confidence.
If you want a plan that actually works for your body, apply here for Nutrition for Runners.