Carb loading doesn’t mean eating a mountain of pasta the night before your marathon. And it definitely doesn’t need to be complicated.
It’s simply a way to maximize your body’s stored energy before taking on 26.2 miles.
Knowing when to start, how many carbohydrates to eat, and which foods work best can help you arrive at the starting line ready to run.
Here’s a simple guide to carb loading for your next marathon.
What Is Carb Loading and Why Does It Matter?
Your body stores carbohydrates as glycogen in your muscles and liver. During endurance running, glycogen is an important source of energy.
As you run, those stores gradually become depleted. When glycogen availability gets too low, maintaining your pace becomes increasingly difficult.
Carb loading helps maximize glycogen stores before race day, potentially delaying fatigue and helping you maintain your effort longer.
The goal isn’t to eat as much food as possible. It’s to increase your carbohydrate intake while your training volume decreases during your marathon taper.
When Should You Start Carb Loading for a Marathon?
Start carb loading approximately 36–48 hours before your marathon.
For a Sunday morning race, that generally means starting Friday morning.
Some runners prefer beginning three days before the race, giving themselves more time to spread carbohydrates across meals and snacks.
You don’t need to carb load for an entire week, and you shouldn’t rely on one enormous pasta dinner the night before the race.
A couple of well-planned days can make a meaningful difference.
How Many Carbs Should You Eat Before a Marathon?
For marathon runners looking to maximize their glycogen stores, sports nutrition guidelines commonly recommend:
4.5–5.4 grams of carbohydrates per pound of body weight, per day, during the final 36–48 hours before the race.
This is a high-carbohydrate loading protocol, and the amount you need may depend on your training, experience, and digestive tolerance.
Marathon Carb Loading Chart by Body Weight
| Body Weight (lbs) | Carbs Per Day |
|---|---|
| 100 lbs | 455–545 g |
| 110 lbs | 500–600 g |
| 120 lbs | 545–655 g |
| 130 lbs | 590–710 g |
| 140 lbs | 635–760 g |
| 150 lbs | 680–815 g |
| 160 lbs | 725–870 g |
| 170 lbs | 770–925 g |
| 180 lbs | 815–980 g |
| 190 lbs | 860–1,035 g |
| 200 lbs | 905–1,090 g |
Daily carbohydrate targets are approximate and rounded to the nearest 5 grams.
Do You Really Need That Many Carbs?
Those numbers probably look surprisingly high. That’s because they are!
The recommendation above is intended to maximize glycogen storage, but some recreational runners may find it difficult to comfortably consume that amount.
A more manageable intake of approximately 3.6–4.5 grams per pound of body weight per day may be easier for some runners, although it may not maximize glycogen stores to the same extent.
The important thing is to find an approach you can tolerate, practice it before race weekend, and avoid trying to cram everything into one or two meals.
What Are the Best Foods for Carb Loading?
You don’t need expensive supplements or specialty foods to carb load successfully.
Some of the easiest carbohydrate-rich options include:
- Bagels and bread: Convenient, easy to portion, and generally low in fat.
- White rice and pasta: Great options for lunch and dinner.
- Potatoes: A versatile source of carbohydrates.
- Bananas and applesauce: Easy snacks that provide additional carbs.
- Pancakes and waffles: Good breakfast options with familiar toppings.
- Pretzels and crackers: Simple snacks throughout the day.
- Sports drinks and fruit juice: Liquid carbohydrates can make higher daily targets easier to reach.
- Honey, jam, and maple syrup: Easy ways to add carbohydrates to foods you’re already eating.
A Few Tips for Easier Carb Loading
Spread your carbohydrates across breakfast, lunch, dinner, snacks, and drinks instead of relying on a few very large meals.
If you’re prone to digestive issues, consider reducing high-fiber foods during the final day or two before your race.
You don’t need to eliminate protein or fat. Just make carbohydrates the priority.
And stick with foods you already know work well for your stomach.
What Should You Eat on Marathon Morning?
Your race-morning breakfast is another important part of your fueling strategy.
General sports nutrition recommendations suggest consuming approximately 0.45–1.8 grams of carbohydrates per pound of body weight in the 1–4 hours before exercise.
That’s a broad range covering different meal sizes and timing windows. It doesn’t mean you need to consume the upper end just an hour or two before the race.
A smaller meal may be appropriate when eating closer to the start, while a larger meal may work when you have more time to digest.
The best approach is to practice your breakfast before long runs and determine what works for you.
My Personal Go-To Marathon Breakfast
Personally, I keep my race-morning breakfast incredibly simple.
I don’t want anything complicated, and I definitely don’t want something that’s going to upset my stomach before running 26.2 miles.
My breakfast consists of:
- 1 large bagel
- 1 whole banana, sliced on top
- 1 tablespoon of raw honey, drizzled over everything
That’s it!
Depending on the size and brand of the bagel, this meal provides approximately 95–115 grams of carbohydrates.
I typically eat it about two hours before the race.
It’s easy to prepare, travels well, and most importantly, it’s something I know works for me.
Your ideal portions may be different based on your body weight, how long you have before the race, and what your stomach can comfortably handle.
My biggest advice: Don’t experiment with breakfast on race day.
Use your long runs to practice your race-morning meal, including how much you eat and how long before running you eat it.
Don’t Forget to Fuel During the Marathon
Carb loading helps maximize your stored energy, but it doesn’t eliminate the need to fuel during your marathon.
For long endurance events, many runners can benefit from consuming approximately 60–90 grams of carbohydrates per hour during the race.
However, higher carbohydrate intakes require practice. Some runners will need to begin with lower amounts and gradually train their digestive systems to tolerate more.
Common fueling options include:
- Energy gels
- Energy chews
- Sports drinks
- Other familiar, easily digested carbohydrate sources
Develop your fueling strategy during training so you know what works before race day.
Final Carb Loading Tips
1. Start early enough. Begin approximately 36–48 hours before your marathon rather than relying on one big dinner.
2. Spread out your carbohydrates. Multiple meals, snacks, and drinks can make your daily target easier to reach.
3. Keep foods familiar. Race weekend isn’t the time to experiment with new meals.
4. Be mindful of fiber. Reducing high-fiber foods may help minimize gastrointestinal discomfort.
5. Stay hydrated. Glycogen is stored with water, so a temporary increase in body weight during carb loading is normal.
6. Practice your race-day plan. Your long runs are the perfect opportunity to test your breakfast and during-run fueling.
The Bottom Line
Carb loading is one of the simplest ways to prepare your body for the demands of a marathon.
Start approximately two days before your race, prioritize carbohydrate-rich foods, spread your intake throughout the day, and stick with a familiar breakfast on race morning.
You don’t need a complicated nutrition plan. You need a plan that works for you.
You’ve already put in the hard work during training. Now give your body the fuel it needs to make the most of that training.
Train Like You Mean It.
Jon Wade | RRCA Certified Running Coach
Preparing for your next marathon? Explore my personalized running coaching and race training plans to help you train smarter, improve your performance, and arrive at the starting line ready to run.