7 Carb Loading Mistakes to Avoid for Your Next Marathon

In the lead up to a race, one of the first questions I get is “will you have pasta the night before the race?” Because it’s all about the carb loading, right??

For years, we’ve heard of nothing but the glorious days of carb loading for marathon day. Mounds of bagels, beautiful plates of pasta and let’s not pretend we shun the cookies.

Not any more.

After my first few races, I realized that for the most part carb loading before a race left me feeling groggy, bloated, and lethargic.

It turns out this is a rather common feeling among many runners, but they don’t realize that the cause is the carb loading myths, which we’ve passed around from runner to runner.

Not to mention that 1 plate of pasta isn’t carbo-loading.

After personal experimentation, research, and yes using my willing athletes as test subjects too, I’ve found that avoiding these carb loading mistakes can make for a much better race day.

In this article, you’ll learn what exactly is carb loading, how to card load correctly and the 7 common mistakes endurance athletes make when carbo loading.

What is Carb Loading?

First for those new to the concept, here is what carbohydrate loading is:

Carbohydrate loading is a strategy involving changes to training and nutrition that can maximize muscle glycogen (carbohydrate) stores prior to endurance competition.

It was invented in the 1960s by a British runner, Ron Hill, who then went on to win a gold medal in the European Athletics Championship. He had a strong finish in the final six miles, the point at which many runners experience the phenomenon known as ‘hitting the wall’.

It’s very common to experience this feeling when your glycogen stores are depleted, and your physical performance starts to nosedive.

While running, the body relies on two forms of carbs for fuel.

1. The first is dietary carbs, namely the ones you eat just before the race.
2. The second is to store glycogen.

The main purpose of carb-loading is to train your body to store as much glycogen as possible, so you have energy on reserve for endurance events.

This is why endurance athletes believe that by loading the muscles with glycogen, they can prevent ‘hitting the wall’ and thus allow us to run at our desired pace for a longer duration.

Why is Carb Loading So Popular?

Carb loading has the potential to improve performance by 2-3%. For a 2 hour half marathon that is an improvement of roughly 2.4 to 3.6 minutes or nearly 7 minutes for a 4-hour marathon.

AHHH now we see why people are so excited to try this.

A 2 to 3-minute change in time is the difference between making that sub 2 hour half marathon goal and being just over it once again.

Unfortunately, most of us don’t fully understand what carbohydrate loading is and our well-intentioned pasta dinner leaves us with a 2% decrease in performance instead!

Too much too read?? I’ve got a video saying it all too:

Common Carb Loading Mistakes to Avoid

As any great sports nutritionist will tell you the value of doing carbohydrate loading before a marathon is high, but only when you’ve done it correctly.

And when you have trained your body to appropriately use carbohydrates.

And when you know your body! (i.e. slight difference for running after menopause!)

In other words, it’s easy to just use this time to eat more carbs and not actually see benefits.

1. Skipping Carb Depletion Phase

This is the one area that many folks never hear about because we want to get straight to the part about eating!

If you’ve been consistently eating a high-carbohydrate diet, you won’t see the benefits of carb loading as much.

If you want all the benefits that come with carbo loading, you need to systematically go through the carb depletion phase to reap all the benefits!

Here is the process on how to carb load correctly as described by The Complete Nutrition Guide for Triathletes by Dr Jamie Cooper, an assistant professor of sports nutrition:

Phase One: Seven days before the event do a long or strenuous workout that will deplete your body of glucose.

Phase Two: For the next 3 days maintain a lower carb diet of 35-50% of total calories

Phase Three: For the final 2 days before the race increase your carbohydrate intake by switching to 75% of calories from carbohydrates, while dramatically decreasing overall work volume (the other 25% is largely protein).

In terms of grams, it’s recommended to consume approximately 3.5 to 5.5 grams of carbohydrates for every pound of body weight.

To convert this into kilos, this is approximately 8 to 12 grams of carbs for every kilogram of body weight.

2. Not Picking the Right Carbs

We’ve heard it a million times “not all carbs are created equal” and yet somehow in the lead up to race week we toss aside our normally good habits for junk food carbs.

Taper crazies, race day nerves and emotions are running high, which is part of what leads us to sugary treats.

Do your best to save those as a post race refuel (along side that green smoothie). Think of race week as your time for the best optimal nutrition.

This is your chance to give your body all of the nutrients it needs to repair from the training cycle and fill your muscles with fuel that will get you to the finish line.

Best food for carb loading: fruits such as bananas, oranges, white rice, grapes, vegetables such as potatoes, squash, sweet potatoes and whole grains. And yes this is the one time that my Sports Nutritionist friends recommend fruit juices.

Especially on that final day when you’re aiming for up to 75% carbs and may not be feeling like downing a ton of food.

A huge pasta dinner only works for a few folks…sorry!

Though it does seem that eating a lot of bagels works for some, if you aren’t used to a high volume of bread it may not be the right choice.

The one caveat here is if you have trouble with high-fiber foods causing you to experience runners diarrhea, then it’s best to steer clear of them. Examples of high-carb foods that are also high in fiber include:

• Beans
• Lentils
• Chickpeas
• Green peas
• Broccoli

Instead, look for options like sourdough bread with honey or sweet potatoes which are lower in fiber. Sourdough also has the benefit of aiding digestion!

Did you know carb-depletion is required to make carbo-loading effective?! Learn more >> Click To Tweet

3. Carb Loading Unnecessarily

If you’re doing a 5K or 10K, stop green lighting a week of carb-binging.

If you’re doing a race that will take you longer than 90 minutes, then you can start to add in extra carbs per the above process.

Additionally, very few runners are training on a true low carb diet, with the exception of my CrossFit Endurance friends. In their case, adding in some sweet potatoes during race week is enough to stock glycogen stores.

👉Try these energy ball recipes for some treats that will give you energy pre, during or post race>>

4. Carb Loading Too Long.

Carbohydrate loading needs only to be done for about 2 days prior to the race, not 7.

The entire process is up to 2 weeks long. But the part which we hear about so much…yup only 48 hours or so.

👉Checkout this guide to what to eat before a marathon. Ideas for the last few days and night before dinner.

Who doesn’t want a week of morning bagels and afternoon granola bowls? In reality, we only need a couple of days after the depletion mentioned in mistake #1 to optimally fuel muscles.

However, in those 2 days you do need to ensure you’re getting the recommended 75% of calories from carbohydrates to see the effects.

5. Freaking Out at Weight Gain.

Carbs make you retain water…this is actually a blessing on race day to help you prevent dehydration!

Just remember you’ll be losing most of that water. If you’ve been loading on good carbs you haven’t put on any actual fat in those 2 short days. No matter what the scale might tell you.

If you’re going to undertake carbohydrate loading, then do it all the way. Don’t let the scale stop you from getting race day results. Unless of course you’re ignoring mistake number 2 and gorging on pre-race cookies.

6. Skipping Your Last Carbo Load Opportunity

Nerves result in stomach issues for a lot of runners/triathletes, so they try to skip out or skimp on race morning fuel.

You must give your muscles this last boost of glucose to help you prevent energy lulls, mood swings and obviously fatigue.

When you eat a meal high in sugar it releases insulin, which tells the body to start storing glucose for later because it has sugar available for energy at that moment.

Your 2 days of carbo-loading is now being stored in your muscles instead of freely available when you start the race.

Aim for 1-3 grams (depending on how far in advance you eat) of high quality carbs, low fat and low fiber – oatmeal with banana or yogurt w/ fruit if you can stomach it.

👉Read more on the best fuel pre-race meal for digestion and performance>>

7. Loading with a Pasta Dinner

As noted earlier, one large meal of carbohydrates is NOT carbo-loading and for many people has the opposite effect of what they desire.

If you haven’t been following the depletion, taper and refueling method described in the first step then you are more likely to experience a sugar crash, which could leave you with night sweats (hmm that sleepless night might not just be nerves).

And a race morning feeling lethargic and tired as your body continues working to balance your blood-sugar.

There’s nothing wrong with the pasta before running, but maybe not 2 servings, plus bread and a slice of cake.

A smaller meal (with some protein) is going to digest easier, allowing you to sleep better and wake up ready to get in that last bit of fuel.

Here are more examples on what to eat the night before a long race.

Why you should skip the pre-race pasta dinner #runchat Click To Tweet

Having gathered all of this information, I will still say that as with all racing techniques, I think it’s personal.

You have to find out what works best for you!

I personally love eating veggies the day before a race even though everyone says not to…and I don’t drink 10oz of water every before a meal because that makes me want to hurl.

But if you are considering carbo-loading now you have more info to get the most out of it!

If your focus is getting to racing weight then checkout the book Racing Weight by Matt Fitzgerald which also talks about fueling and the impact of carbs.

Have you ever tried carbohydrate loading?

What was your experience?

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