Marathon Carbohydrate Loading

SpaghettiOk, so you have a Marathon coming up.  You have trained for the past 14-18 weeks, put in the long runs, and now it is time to race. Everyone knows to “carbo-load” right?  So the night before a race you’re going to go out and eat a big plate of spaghetti, right?


Although that is what I did the first few races, I now know now how wrong that is.  Most endurance athletes make that same mistake and their performance suffers because of it.   Carbo-loading is mainly for endurance events longer than 90 minutes.  Carbo-loading when done effectively is the best way to prepare for that endurance event.

Your body stores carbohydrates (as glycogen) in the muscles and liver to be used later.  Without carbo-loading, your body stores only enough fuel to last for about 90 minutes of exercising.  After that you will “hit the wall,” or “bonk”; no matter what you call it, it will not be pleasant.  Carbo-loading also helps you hydrate for your race.  For every gram of carbohydrate you store, three grams of water attach to it.  So if you carbo-load effectively, you will gain around five pounds.  But not to worry, it is water weight and fuel that you will use up during the race.

So how do you carbohydrate load effectively?  For a 150-pound person, eat 560g – 700g per day for 2-3 days.  To reach that goal, it isn’t necessary to radically increase your calories, just simply increase the proportion of carbs on your plate.  Eat little and often to get enough carbohydrates. Instead of three super-sized meals, eat three regular-sized meals and add three snacks between meals.  Eating 560g of carbohydrates can be tough, so if you find it too much, instead of eating every day 560g build up to it.  Eat 3gx (your weight in lbs) the first day, 3.5gx (your weight in lbs) the second day, then 4g times your weight in lbs the third day.  So in the example above, a 150lb person eat 450g the first day, 525g the second day, and 600 grams the third day.  When you carbo load, don’t just eat everything you see.  Eat foods high in carbohydrates, like Potato’s (sweet potato is best), Rice, bread and of course noodles. When you break out your calories for the three days leading up to the race, try to eat 70% – 80% carbohydrates.  Remember, don’t just stuff yourself.

Here is the plan that I use:

  • Breakfast:
  • 1 bagel with 2 tablespoons strawberry jam (71 g)
  • 1 medium banana (27 g)
  • 8 ounces fruit yogurt (41 g)
  • 8 ounces orange juice (26 g)
  • Total 165 g
  • Morning Snack:
  • 2 Nature Valley Oats ‘n Honey Granola Bars (29 g)
  • 8 ounces Gatorade (14 g)
  • 1 scoop Karbragous  (40 g)
  • Total 83 g
  • Lunch:
  • Large baked sweet potato with ¼ cup of salsa (69 g)
  • 1 sourdough roll (40 g)
  • 8 ounces chocolate milk (26 g)
  • Total 135
  • Afternoon snack:
  • 1 Clif Bar (42 g)
  • 8 ounces Gatorade (14 g)
  • 1 scoop Karbragous  (40 g)
  • Total 96 g
  • Dinner:
  • 1 chicken burrito with rice, corn, and black beans (105 g)
  • 1 scoop Karbragous  (40 g)
  • 1 scoop Generation Ucan (20 g)
  • Total 165

Add that up and you have 644 grams of carbohydrates.  Honestly, I never get that much, but it is just a guide.  I don’t eat the exact foods but use the numbers to help.  I do drink the Karbragous and Ucan that much is for sure.  Everything else is on the table, just fill in the numbers.  So now you know how to properly carbo-load.  You will still need to refuel during a marathon using UCAN, GU or sports drink.  Remember never try a new fuel in a race, use what you have been training with. But with proper carbo-loading, you are sure to reach your potential and hit that PR goal instead of the wall.


About Coach Bill

I am a 48 year old runner. Three years ago I ran my first half marathon and have not looked back since. I am married, have two grown son's. I work at Toyota motor manufacturing Texas building Tundra's and Tacoma's as a skilled team leader in the press department.
This entry was posted in Advanced Runner, Beginner Runner, Marathon Training, Nutrition, Running Coach, Uncategorized and tagged , , , , , . Bookmark the permalink.

2 Responses to Marathon Carbohydrate Loading

  1. Laurel says:

    Great post! It’s funny how many misconceptions about carbo-loading there are. Many people view it as just eating more than normal and don’t understand the science behind it.

    • Coach Bill says:

      Thanks, we all have to learn. I am amazed when I go to a race and talk with other runners how little they know about eating to fuel your body. They will train hard, run in the rain, do track workouts, plan for 4 months and work hard, then goof it all up three days before a race.

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