Guest Post: Carb Loading – The Truths And Myths Of Loading Carbohydrates Before An Endurance Race

The following post comes from the hugely talented Cara Haley from and An excellent read for both endurance athletes and bodybuilders seeking to manipulate their carbohydrates before a strenuous session, the article will no doubt be of interest…Enjoy!

If you are a runner, you have probably heard and are doing your carb loading before a marathon or another endurance race, but the question is – are you doing it properly?

Carbohydrate loading is crucial for the proper preparation for any endurance running test, but it is important to understand what it actually should consist of so that you make sure that your body has been properly fueled to complete the marathon or other race you are preparing for.

Car loading is not just eating a big pasta dish on the night before the race, it is more of a lengthier and systematic carb loading practice which you should practice for a few weeks while preparing for a marathon or ultra-marathon. This is important so that your muscles get maximum glycogen storage so necessary for the race.


Carb loading methods

Carb loading has been found to be effective only if you are preparing to take part in an endurance event which is longer than 90 minutes, including: triathlons, marathons and ultra-marathons because studies show that the body muscles loose the stored glycogen in about 90 minutes or soon after that when racing or other endurance exercising. This means that if you are preparing for a 5k or 10k run, carb loading is not effective for your performance at all, and can actually lead to the stiffening of your muscles and a lowered performance.

Method #1 – The long taper plan

If you choose to follow a long taper plan, the last hard training session should end 3 weeks before the race. In the final 2 weeks you should taper your training. While at it, your body does not need added calories, because you will not be burning as much calories during the taper period. Just keep eating 3-5 grams of carbs for every pound of your body weight, and make sure you reduce the intake of fat, because your body will not be requiring as much energy as during the hard training period. The added carbs will help build up the muscle glycogen storage necessary for an endurance race of 90 or more minutes.

Method #2 – The 6 day carb loading plan

This protocol includes adding some glycogen depleting exercising on the 6th day before the race or endurance event, such as adding very intense sprinting to your training if you are running a marathon or ultra-marathon. In the first 3 days of these last 6 days before a competition, you should continue eating your normal diet of 2-3 grams of carbs per pound and do tapered training. In the last 3 days prior to the race, as you reduce the training, you should begin consuming more carbohydrates (about 4.5 grams per pound of your weight) and reduce the fat intake.

Method #2 The rapid carb loading

This is suitable if you have more competitions planned for the year, or haven’t had the proper training to fully prepare for your race, and really need those last weeks of training to improve your fitness and performance. This goes for runners who do not need to taper before endurance runs too. This method involves a 24 hour carb loading preparation and managing to store up that glycogen in the muscles for 24 hours to be ready for the endurance event. This is done by doing some glycogen depleting exercises 24 hours before the race, and right after that begin consuming higher quantities of carbohydrates (5 or 6 grams per pound). This should continue throughout the day before the competition. This means that a runner who weighs 150 pounds should intake 750 grams of carbohydrates (3,000 calories worth) for the day and to do that the intake of proteins and fats must be reduced to a minimum.


Tips for the best personal results

Here are some tips on finding the ultimate carbohydrate loading plan to follow before running a marathon or other endurance run and getting the best personal results while at it:

  • Remember that the carb loading plan you follow should be in accordance to the type of race or endurance event you are preparing for. The number of other events which you will be participating in during the year is also important.
  • Whichever method you choose to get your muscles ready for an endurance race via carb loading, remember that you should be careful when doing so, because there are some risks of developing intestinal problems and constipation if you rapidly increase the carbohydrate load. Adding some fiber rich foods during the period can help promote your bowel movements, but you must find the right balance and be careful not to eat too much of these because this can lead to the opposite problem – diarrhea.
  • Also, protein helps the synthesis of glycogen, and is also a great secondary fuel reserve, so remember to eat proteins as well in the days and weeks before a race.
  • Keep in mind, that it is normal that you gain some weight during your carb loading (about 2-4 pounds), but don’t worry because this is water weight. Boosting the storage of glycogen in the muscles leads to an increase of the storage of three times more water in the body too. You may feel like your muscles are heavier on the day of the race, but throughout the race, your body will use up both the glycogen and the water storage, so don’t worry.


  • As for the type of carbs to eat while carb loading make sure you choose carbohydrate-dense foods and drinks, such as sports drinks, gels and juices. Also, don’t forget to consume a sufficient amount of whole grains which will compensate for all the sugar you are consuming during the carb load.
  • Please, do not try to make up for not getting sufficient carb loading by eating a heavy meal on the night before the race though. This will make you feel uncomfortable and full and will hinder your performance.
  • Eat your last large meal earlier on the day before the race.
  • Also, make sure that you prepare and consume sufficient amounts of fluids and energy sources during the race or endurance event itself to stay properly fueled until the finish line.


About the author: Cara is coffee lover, running addict and all about healthy food. She writes about her running and fitness journey on her blogs and


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