A Practical Guide to the Carbo Load (aka, why I love the taper)

By Jeff Knight

If you’re like me, the taper drives you crazy. Phantom injuries, heavy legs, nightmares of waking up to the sound of the starting gun on race day (!) and a paralyzing feel that you are magically out of shape. But, BUT, there is one bright spot among all this. No, its not getting to wake up at 5:00AM instead of 4:40AM (that’s nice too) instead, its these two words: carbo load.

zazzle.com (fun to say, goofy shirts)

zazzle.com (fun to say, goofy shirts)

Yes, I admit, I have – what will undoubtedly be the cause of an actual soft spot if I quit running – a soft spot for carbohydrates. Imagine the scene from American Beauty where the girl is covered in rose petals. I imagine that as bagels instead of rose petals. Or think Scrooge McDuck swimming through a vault full of pasta. Thats me. This, while typically a nemesis of training, I’ve found has served me well for one week of the training cycle.

And while the skeptics out there may call carbo loading a product of the evil grain lobby, I disagree. I believe carbo loading has some real value and that’s what we’ll cover today. I’ll break down why we should carbo load, give some historical context, talk about current methods and provide a practical guideline. So grab a potato and read on.


Before we take this as a hall pass to stuff our faces with croissants, lets understand why we stuff our faces with croissants.  Just like a car engine, our bodies use fuel when we run. However, we are more like a hybrid car in that we use a mix of fuel sources. The two main fuel sources we use when running are carbohydrates and fats. And while there is some interesting talk of high, HIGH-fat diets being the new silver bullet for endurance running, currently, the most important fuel source for marathoners or half marathoners is carbohydrates.  (On an unrelated note, if you ever want me to get on my soap box, ask me about low carb diets for runners.)

Why are carbs so important? Lets look at a graph…

….Stay with me!!…

….its just one graph…and maybe a table but one graph for now! Silly picture will come later.

Relationship between running pace and fuel usage.

Relationship between running pace and fuel usage (numbers and such are hypothetical and simply represent the relationship).

The above graph shows the relationship between the type of fuel we use when exercising and the pace at which we exercise. As you can see, the distribution between fats (green line) and carbs (orange line) are opposite. If we start with a walk, we use primarily fat. As we speed up to an easy-paced run, we sill use primarily fat but a little more carbs. Then as we get to marathon pace or half marathon pace, the two lines cross and we find ourselves using more carbohydrates than fats. We can continue this all the way to a 400-meter sprint where we use virtually zero fat as fuel.

“as we get to marathon pace or half marathon pace, the two lines cross and we find ourselves using more carbohydrates than fats.”

“So what?” you might ask, we use more carbohydrates than fats when racing. Well, carbohydrates are stored in limited supply in the body. Normally we carry enough around to run ~16 miles at MGP. A la, “the wall” at 16 miles. This means fuel and NOT fitness is going to prevent us from reaching a goal.  That sucks! (This is in comparison to fat, which we store enough fuel to run like 1,600 miles.) But, BUT, what’s even more crazy is under a normal diet, we only keep our glycogen fuel tanks full to 90%! And, the good news is we can do something to store more carbohydrates than we normally do. We can do something to fill the fuel tanks that final 10% and that is carbo loading.

To summarize, the crux is carbohydrates are the most important fuel source during the race and we don’t store enough under normal conditions to sustain race pace beyond ~16 miles. Then the question becomes, how can we store more fuel than normal? How do we store enough fuel that, in combination with gels/chews, that fuel doesn’t limit our race performance?  How can we go into the race with the fuel tanks topped off instead of leaving them at our normal point of 90% full?


(I like this stuff which means you have to suffer through it with me – XOXO) Back in the 1960s, some grad students were sitting around bored. (I’m assuming) They were probably runners or cyclists and they had some equipment to look at how much carbohydrates they could store in the muscle (e.g., a muscle biopsy).  They also knew that if you worked out really hard, ate a lot of bread that you’d have more carbohydrates stored in your muscles than normal. Knowing that carbs were an important fuel, they did what any bored grad student would do, they started screwing around with the best ways to maximize carbohydrate storage. One of these guys was names Ahlborg and so this went on to be called the Ahlborg method.

The Ahlborg method went like this. About a week out from your key race, you run yourself to pieces. Think a monster track workout (maybe 6x1M at 10k pace). After that workout, they would essentially starve themselves with an Adkin’s Diet (2010, yall!). After starving for a few days, they would do ANOTHER monster workout except this time, they would go carb-crazy post workout. Then over the next few days until their race, they would eat and eat and eat every carb in site. The end result was the fuel tanks would be at 100% entering the race. Moving those tanks from the normal 90% full up to the now, topped-out 100% is called supercompensation.

See any problems with this? How about two huge workouts the week of your race? How about a low-carb diet the week of your race? We also know how important carbs are to recovery (chocolate milk, anyone?) and not having that after the first workout?

Basically, runners would feel like shit for three days in the final week before their A-race and they would sometimes get hurt from the low-carb diet. How is that for the final week of the taper?? Super good for the head, right?!?!



Fortunately there are some new methods that are almost just as good as the Ahlborg method when it comes to storing carbs and far superior when it comes to not being a mental wreck on race week (think sobbing, fetal position, dark corner).

Thankfully, in the 1980s, some even more bored grad students got tired of feeling like shit on race week. They found out that you can get the tanks to 100% without the supercompensation effect.  These guys basically found that if you just do your normal diet (50% carbs) up till the final 3 days before your race and then stuffed your face with every carb in site, you could fill the tanks up to just about the same level as Ahlborg and Co. “What type of running did the do?”, you might ask. Basically what we would do for a taper. A basic drop in mileage each day with all runs at a moderate pace.

Man, thats like so simple. Like, why the hell didn’t we do that in the first place? That said, everything was a little more gritty when it came to endurance sports in the 60s.

1960 Rome Olympics - Marathon (no Hokas in that one)

1960 Rome Olympics – Marathon (no Hokas in that one)

Anyways, thank goodness for these guys. They should get an award.  Like maybe we should name the method after them!

Nah…lets just call it the Non-depletion Method (not my choice!). Poor guys.

Anyways, there are still some practical problems with the Non-depletion Method:

  1. Carbs make you bloated. Everytime you store carbs you store water. Carbs love water. Thats just their chemistry. While this water isn’t bad from the perspective of race-day hydration but it does make you feel like a fatty.
  2. Along the same lines, no one likes to feel like a fatty the day before a race.
  3. If you typically don’t eat a ton of carbs, carbo loading may cause stomach issues on race day if you don’t provide time to normalize.

As a result, here is the method I like for carboloading

T-7 Days T-6 Days T-5 Days T-4 Days T-3 Days T-2 Days T-1 Days Race Day
Mixed Diet Mixed Diet High-carb Diet High-carb Diet High-carb Diet High-carb Diet Carb-heavy breakfast, normal diet the rest of the day. Eat food that makes you feel fast. Is that smoke from my shoes?

**The running portion of this method is your normal, taper-week running. 

First off, if you skipped my asterisks (never skip the asterisks!), this method does not require you to do anything different with your running. Just run like normal. Next, up until 5 days from race-day, just eat a normal, mixed diet. The mixed diet is a roughly a 50/50 mix of carbs to fat+protein.  I define this as normal because thats probably true for most folks. On any given day, a distance runner is probably going to derive half of the calories in their diet from carbs while the other half comes from a blend of fat and protein. Running isn’t a strict science so lets not go crazy here either. Ballpark 50/50.

Next, starting 5 days from race day, ramp up that carb intake. At this point your want to derive 70% or more of your daily calorie intake from carbs! Yep, its time to feel like a fatty. A grumpy-cat, fatty.


(au.news.yahoo.com) Cat pictures help you get up-votes on reddit

Keep eating every delicious, beautiful carb until T-1 day. Finally, on the day before the race, you should taper off of the carbs and start eating like normal. Maybe do a late breakfast/brunch with pancakes or french toast but from there on out, eat what you like. Whether thats salad, grilled chicken (protein) or maybe even rice. Whatever it is, I strongly encourage you to normalize that day before the race.

I believe this method will help you top the tanks off to 100% 36-48 hours out while allowing you to keep those tanks and get your normal diet into place when it matter most. Plus, plus, this may help give you a little wiggle room if you don’t quit nail that 70% number on all 4 days. In otherwords, say you travel 2 days from your race and you don’t quite get 70% of your calories from carbs, no worries, you’ve been nailing it your other days.


Now a rebuttal to a question that wasn’t even asked. If you take gels on race day, carboloading may be considered a safety net. In fact, some exercise physiologists would argue carbloading is pointless if you take gels on race day but, as a coach, I disagree. While we gel on race day, most of us don’t take in near enough fuel to fully support the effort.  The recommended fuel intake during a marathon is 1-1.2 g/min…so 60 to 70 g of carbs per hour. If one gel is 25-28g of carbs, you’d need 2+ gels per hour or two gels and gatorade per hour. Who does that out there?

This is why I believe a combination of carboloading and gels are the best way to ensure you do not bonk on race day. (If you don’t gel, then carboloading is KEY!!)


That whole 70% carbs thing is confusing. Sure there are apps and stuff but I have I also have an easier method.

Math. First off you need your weight. Get on scale but before you do it flip it over and flip the switch to the unit that all the rest of the world (except Madagascar) uses, KG. If you have a discriminatory scale, you’ll probably want to Dogpile “how many kG are in [insert weight in lbs] lbs”. Or if you’re really old school, you’ll take your weight and divide by 2.2.


From there, the goal is to get 8-10 g of carbs/kg of bodyweight. Meaning, if you weight 50 kg, you would need 400-500 g of carbs that day.  Lets check my math, assume 4 calories per gram of carbs. That makes 1,600 to 2,000 calories from carbs. If you normally eat 2700 calories per day, that would mean you’d get you 60-75% of your calories from carbs. Not bad. This is much easier for me because all you need to do is look at the back of packages and boxes. Or yahoo “how many g or carbs are in [insert item]?”

Be aware though. This is a lot of carbs. Like a lot. Here is an after-hours text message from one Chris McClung.


This is a sampling of after-hours texts between Rogue Employees #supercool

If you mess this part up its because you totally estimate how many carbs you are taking in so below I’ll give you an example diet as well as some ideas for getting some bonus carbs in.


For this example, lets take person that weighs 150lbs (male or female), thats 68kg. According to the conversion of 8-10 g of carbs/kg of bodyweight, that person would want to ingest between 550-650g of carbs per day during the carbo-loading phase.

Lets see how that might break down:


  • Cinnamon Raisin Bagel – 55g Carbs
  • Honey (1 tbls) – 17g
  • Taco Deli – Black bean, avocado, pico – 30g
  • Smoothie – 55g
  • Coffee with cream and honey – 10g

Mid-morning snack 

  • Skratch (16oz) – 20g
  • Muffin – 50g
  • Apple – 19g
  • Honey Peanut Butter – 8g


  • Stir-fry (a la White Chicken and Broccoli from Zen) w/ extra rice – 75g
  • Melon (1.5C) – 22g
  • Picky Bar – 28g

Afternoon snack 

  • Fruit, Plain yogurt, Honey and Granola – 42g
  • Coffee with cream and honey – 10g
  • Skratch (16oz) – 20g


  • Pasta with veggies and sauce – 55g
  • Garlic Bread (2 slices) – 15g
  • Strawberries (1C) – 12g

Post-dinner snack 

  • Two slices Toast – 18g
  • Jelly (2 tbls) – 30g

Grand Total: ~591g Carbs

Whew! I’m stuffed!  So whats the theme here?  To me, its a few fold.

  1. Eat sweet and eat often – think fruit, honey and grain everywhere. Smoothies are particularly nice because they are so dense. Snacks between every meal are key!
  2. Drink it – Skratch, Sports drinks (beware of 0 calorie!) or Juice. Also, add honey to coffee or tea even if you don’t normally.
  3. High quality – While processed grains (white rice, white bread) are more dense, you can get by with the whole grain types. Also, notice you could add soda, cake, donuts or other low-quality stuff in there but you don’t have to. Keep that in mind!
  4. Cook it and pack it! – Eating this much takes planning.

When its all said and done, race day will be here and you will be prepared to rock and roll. And, if you are like me (e.g., carboholic), this is the best part of the training cycle (outside of the neurosis), so grab a fork and chowdown with the same tenacity as you hit those miles.

headshotJeff Knight is the head of all things training at Rogue Running. He loves to use “his scientific background” as an excuse to make everyone run as many hills as possible. He also coaches Team Rogue el Jefe, where they run a lot of hills.  You can reach him with and and all questions at jeffknight@roguerunning.com


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