Carbo Loading: Are you doing it right?

I thought I’d get this together for a good friend of mine Cris who is running the London marathon this weekend.  If you are reading this Cris… (or if you are anyone doing the London marathon this weekend)… good luck!  🙂  First off, here’s something I wrote before: Carb Loading

Carbo-loading can help you race without hitting the wall—as long as you do it right.  Most people know about carb loading or at least that you should eat carbs before you do a marathon, but some people think of it just as a big bowl of pasta the night before.  It’s not as simple as that.  Carbo loading is where you load up 2-4 days before the event, fueling your body to keep going over 3, 4, 5, 6 hours or longer, and hopefully preventing you from ‘hitting the wall.’

Most runners know they should eat pasta, rice, potatoes, or other high-carb foods before a half marathon, marathon or ultra marathon. After all, carbs are a great source of energy, and you need a lot of energy to cover 13.1 or 26.2 miles or beyond.

But many runners are far less clear on how many carbohydrates they should eat and when to start loading up. Many people don’t carbo-load properly. Runners train so hard and then because they don’t carb load before the event, they arrive with a huge handicap. 

Here’s what every runner needs to know about carbohydrates, so you can toe the line fully fueled and ready to go.

When you eat a bowl of spaghetti, most of the carbs are stored as glycogen in your muscles and liver. Glycogen is your body’s most easily accessible form of energy, but it’s not the only source. During a long run (+90 mins) you burn both glycogen and fat. But the latter is not as efficient, which means your body has to work harder to convert it into fuel.

When you run out of glycogen during a race you hit “the wall.” Your body has to slow down as it turns fat into energy. Proper carbo-loading—or filling your muscles to the brim with glycogen—won’t make you faster, but it will allow you to run your best and, if you race smartly, avoid the wall.

When I tried to Carbo load for the Lochaber Marathon, I probably did it all wrong.  I used rice and good food to carbo load, but I also chose things like mars bars and sweets.  These types of food are fine for on the run for instant energy, but not so good for carbo loading as they are quick release carbs.  You want to eat slow release carbs, the carbs that are healthy and good for you.

So, which carbs should you load up on? You could live on a diet of rice and oats, but runners don’t need to be so restrictive. Tortillas, oatmeal, bread, pancakes, waffles, bagels, yogurt, and juice are all easy-to-digest options. Many fruits are high in carbs but are also high in fiber—and too much can cause stomach trouble midrace. Bananas are a low-fibre choice. And you can peel apples, peaches, and pears to reduce their fiber content. You can also indulge in white bread and baked potatoes without the skin since both are easily digested.

Try to steer clear of high-fat foods—like creamy sauces, cheese, butter, and oils—as well as too much protein. Both nutrients fill you up faster than carbs and take longer to digest, she says. Pick jam—not butter—for your toast, tomato sauce in lieu of alfredo sauce on your pasta, and frozen yogurt instead of ice cream for dessert.

You can’t completely fill your muscles with glycogen from just one meal, which is why you should start carbo-loading two or three days before your race. Since you’re probably in the taper period and running very few miles, the glycogen will accumulate in your muscles. At this point, 85 to 95 percent of your calories should come from carbs. I’d recommends eating about four grams of carbs for every pound of body weight (for a 150 pound (10st 10) runner that’s 600 grams—or 2,400 calories—of carbs per day).

It’s important to keep in mind that you’re most likely not eating many more calories per day than you were during the thick of your training—it’s just that more of those calories are coming from carbs.

If you step on the scale while you’re carbo-loading, be prepared to see a number that’s at least four pounds more than your usual weight. The extra pounds mean you get a gold star for carbo-loading properly. With every gram of stored carbohydrate, you store an extra three grams of water.  That means your body will be hydrated and fueled as you start the race, ensuring you cross the finish feeling strong.

Even if you carbo-load properly, you still need to take in midrace fuel (such as sports drinks, gels and chews) to keep your energy level high through out the run. I take on a gel every 45 mins to an hour and recommend regular water consumption to keep going strong until the end.
A day of carbo-loading for a 150-pound runner

1 bagel with 2 tablespoons strawberry jam (71 g)
1 medium banana (27 g)
Fruit yogurt (41 g)
Half pint fresh orange juice (26 g)

Oats ‘n Honey
Granola Bars (29 g)
Half pint Gatorade (14 g)

1 large baked potato with 1/4 cup salsa (69 g)
1 sourdough roll (40 g)
Half pint chocolate milk (26 g)
1 large oatmeal cookie (56 g)

1 Clif Bar (42 g)
Half pint Gatorade (14 g)

1 chicken burrito with rice, corn salsa, and black beans (105 g)
50g nuts (50 g)



What to do before race day to ensure your tank is full:

6 WEEKS BEFORE: Practice loading
Two or three days prior to your longest run, start eating more carbs and less fat and protein. You’ll get a sense of what foods agree and disagree with your stomach.

1 WEEK BEFORE: Make a plan
A plan is especially important if you’re traveling to a race. Pack plenty of snacks, like sports bars, nutrigrain bars, muller rice, and crackers. Check menus online and make restaurant reservations.

2 OR 3 DAYS BEFORE: Switch to carbs
From now through your race, 85 to 95 percent of your diet should be carbs. Eat after taper runs. That is when muscles are primed to store glycogen.

NIGHT BEFORE: Don’t stuff yourself
Dinner should be relatively small but carb-heavy. Eat on the early side so you have lots of time to digest.

You want to wake up race day hungry—not full from the night before.

RACE MORNING: Have breakfast
Three hours before the start, eat 150 grams of carbs, like a bagel and yogurt or sports drink and porridge.


This entry was posted in Food, Marathon, Special Event, Ultramarathon. Bookmark the permalink.

5 Responses to Carbo Loading: Are you doing it right?

  1. Pingback: Carb Loading Explained |

  2. David says:

    Thanks for this.
    A very clear explanation.

  3. Pingback: So this is Christmas, and what have we done? | Lorn Pearson Trains…

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