Carb-Load Correctly in 3 Easy Steps

sarah cuff Carb-Loading for Runners, Running Performance 5 Comments

If you are participating in an endurance event lasting longer than 90 minutes you stand to benefit from carb-loading and thereby increase your performance by 2-3%¹. The longer the event you’re signed up for, the more important it becomes to ensure your glycogen stores are full (and therefore you are fully carb-loaded). If you’re getting ready to run a half marathon (depending on your anticipated finish time), full marathon or ultra event, carb-loading could mean the difference between bonking and running strong the entire distance.

Let’s take a quick peak at the difference between trained runners who either don’t carb-load, carb-load incorrectly and who get it right. Then I’ll walk you through the 3 steps to carb-loading correctly.

No carb-loading. Let’s say for whatever reason you simply continue eating your normal food right up to race day (note: “normal” for most people is about 45% carbohydrates). Add to this, no real rest – you’re still running around doing errands as usual. You’d have enough glycogen in your liver (liver glycogen is very important because it helps keep blood sugar levels stable and it feeds the brain), to last you about 55 minutes; and enough in your muscles to last you about 70 to 90 minutes. If your race is longer than 1.5 hours, it’s likely you may bonk, especially if you are not taking in adequate gels to fuel you while out on the race course.

Carb-Loading Incorrectly. In this scenario let’s say you know you’re supposed to eat more carbs, so you load up on pasta, french fries, toast, pizza and other starchy foods. You will have more glycogen in your liver and muscles – somewhere between the numbers above and the numbers below, however because you ate more carbs but didn’t lower the amounts of fat and proteins you were taking in, you’ve actually ended up eating more calories overall in the past few days. Therefore you arrive at the start line feeling heavy and bloated. You may or may not have a good race.

Carb-Loading Correctly. Finally, let’s say you do everything right to the letter. You eat 7-10 grams of carb per kg of your body weight for 3 days OR you eat 10 grams carb per kg bodyweight for one day. You rest up the day before, kick the legs up and watch a movie, and relax. You’d have about enough glycogen in your liver to last you as long as 2 hours and 40 minutes; and enough in your muscles to last you as long as 3 to 4 hours. If your race is longer than 2.5 hours, you’ll still need to fuel on the run (to top up blood glucose and supplement the depleted liver glycogen). But you’ll have enough muscle glycogen to keep you going long past the usual 1.5-2 hours.

You can see now why you might want to get this carb-loading thing right. Here are the steps to follow to do so:

1. Calculate Your Numbers

In order to be properly “carb-loaded”, you’ll need to eat 7 to 10 grams of carbohydrate per kilogram of your bodyweight for each of the 3 days leading up to your race²; OR diligently consume 10 grams of carbohydrate per kilogram of your bodyweight for 1 day³ (the day before your race).

Take your bodyweight in kilograms (pounds divided by 2.2) and multiply by 7 and again by 10. For example, a 130lb runner is 59kg and would therefore need to consume between 413 grams carb to 590 grams carb for 3 days; OR 590 grams carb the day before race day.

2. Determine Strategy

You may find the numbers above appear extremely large and maybe even look a bit unrealistic. In fact, not many runners actually achieve them, even when they believe they are carb-loading. One 2011 study, looking at 257 marathoners, showed us only 12% managed at least 7g /kg (and indeed they outperformed those who ate less carb). Carb-loading does work, the trick is figuring out how… And part of that comes down to strategy.

Be sure to eat 3 meals and at least 2 if not 3 or more snacks per day. Eating every 2-3 hours is a good strategy to implement to ensure you’re getting all your allotted carbs in… If you miss a ‘feeding window’ chances are you won’t physically be able to stuff it all in later.

Additionally plan to drink a number of your carbs! It is practically impossible to eat all that’s required as whole food. Choose fresh pressed fruit and veggie juices, pure tart cherry juice, smoothies and shakes, coconut water and kombucha. Literally make a point to be sipping from one carb-rich beverage or another all day long and alongside snacks and meals.

3. Plan Your Menu

This step is key in ensuring that you eat your required number of carbohydrates without eating too many calories overall. Essentially all sources of fat and protein dense calories are removed or limited during the carb-loading period.

The foods you’ll want to reach for will be carb-rich with just a bit of fat and protein, such as:

  • Breakfast – big breakfast of oatmeal or granola with cinnamon, a few nuts/seeds and dried fruit, berries, banana; or a big fruit breakfast shake such as the Chocolate Cherry Berry Recovery Shake; or sprouted grain toast with a touch of nut butter, creamed honey, hemp hearts and sliced banana
  • Snacks – fruit (grapes, apples, mangos, melons, papaya, oranges, kiwis, bananas, etc); carrots/veggies and Mary’s crackers with Hummus; homemade Granola Bars; homemade Banana Bread; homemade Banana Muffins; homemade Power Cookies made with less nuts/seeds and more dried fruit; fruit smoothies; rice cakes with touch of nut butter and generous amount of creamed honey with hemp hearts
  • Lunches/Dinners – a good-sized serving of yams, potatoes, rice (or rice pasta), quinoa (or quinoa pasta), millet or lentils with some veggies and an optional small amount of protein (such as Hearty Rice Salad; quinoa salad with baked yams / potatoes / beets / carrots; Market Fresh Pizza sans cheese; and tomato pasta / tomato rice dishes)

In the 24 to 36 hours before your race begins, you may wish to choose ‘white’ versions of grains (ie. white rice) in order to avoid any extra fibre at all. Additionally, keep leafy greens to a minimum, and avoid/limit red meat, dairy, cream sauces and whole nuts. These foods take more time to fully and completely digest – you would not want any left in your system by the time you begin racing!

Please also keep in mind you should only be eating foods in your carb-loading period that your are familiar with – no new foods in the days leading up to race day!

Lastly, it should be noted that carb-loading does mean you may gain about 1-3 or more pounds in water weight as your glycogen stores fill up. It seems counterintuitive to toe the line a few pounds heavier but it is not fat so it won’t weight you down! For every gram of glycogen you store, approximately 2.7 grams of water is stored with it. This is actually great news as you begin racing, not only are your glycogen stores full but you are also essentially “pre-hydrated”. All the extra weight will be gone by the end of your race as you body burns through the glycogen and water.

Truth be told, carb-loading doesn’t stop the night before your race when you go to bed, what you consume the morning of your race is extremely important to the success of your race also – a topic explored in this post!

To deliciously healthy food and stronger faster running… Cheers,


Sarah Cuff, R.H.N.
Holistic Sports Nutritionist
Founder Eat 2 Run Sports Nutrition
CSNN Sports Nutrition Instructor
Better Bodies Club Nutritionist


1. Sports Medicine. Carbohydrate-Loading and Exercise Performance. 1997. ***Note: Increasing your performance by 2-3% equals dropping about 30 seconds for every 15 minutes you're out racing. For example, if you are trained to run a 4:07 marathon, you may instead achieve a 4:00 marathon with proper carb-loading; a 3:36 marathon would turn into a 3:30 marathon; or for the half marathon a 2:03:30 might become a 2:00; or a 1:45 into a 1:43; and so on.
2. Burke, Louise & Deakin, Vicki. Clinical Sports Nutrition, 4th ed, 2004, pp 306-308.
3. European Journal of Applied Physiology. Carbohydrate Loading in Human Muscle. 2002.

Comments 5

  1. Hi Sarah! So useful I can’t wait to start my carb load for Van Marathon! Can I just clarify – when you talk about eating 7-10g per kg for 3 days or 10 kg the day before – do you mean that you would eat 7-10g per kg every day for 3 days, or that you would eat 7-10g per kg in total over the 3 days?

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  2. Pingback: What to Eat on Race Morning | Eat 2 Run

  3. i randomly came across this on my carb loading google search…this speaks my language and am gonna follow all you said. thanks so much. I am in training for obstacle course races and need more energy 100% !!!

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