How to Carbo-Load without Eating any Carbs


According to a study published in the Journal of Physiology, it is possible to reap some of the athletic performance rewards of a carbo-load without actually eating any carbs.

The Science

Previous studies have shown that the presence of carbs in your mouth activates regions of the brain that can improve athletic performance.

The primary aim of this study was to see how “rinsing the mouth with solutions containing glucose and maltodextrin, disguised with artificial sweetener, would affect exercise performance”.

The secondary aim was to identify those regions of the brain activated by the sugars and artificial sweetener. A functional MRI (fMRI) machine was used to map the brain.

The Test

Prior to completing a cycling time trial, the eight volunteers rinsed their mouth out with a solution of glucose or maltodextrin or a placebo solution containing the artificial sweetener saccharin.

After the rinse, they hopped on their bikes and pedaled as hard and as fast as their legs could go.


  • In study 1A, test subjects “completed a cycle time trial significantly faster when rinsing their mouths with a 6.4% glucose solution compared with a placebo containing saccharin.”
  • The corresponding fMRI study (1B) revealed that oral exposure to glucose activated reward-related brain regions, including the anterior cingulate cortex and striatum, which were unresponsive to saccharin.
  • In study 2A, cyclists who rinsed with the maltodextrin solution once again outperformed their saccharin-swilling brethren.
  • The second neuroimaging study (2B) “compared the cortical response to oral maltodextrin and glucose, revealing a similar pattern of brain activation in response to the two carbohydrate solutions, including areas of the insula/frontal operculum, orbitofrontal cortex and striatum”.


The results suggest that the improvement in exercise performance caused by the carbo-rinse may be due to the activation of brain regions believed to be involved in reward and motor control.

The findings also suggest that there may be a class of so far unidentified oral receptors that respond to carbohydrate independently of those for sweetness.

What does this mean to you?

  • One of the primary benefits of cardio-vascular training is that fat is the primary choice of fuel.
  • This is why cardio training is one of the most popular weight loss tools.
  • However, a lot of trainees hurt their own cause by carbing up prior to a cardio session.
  • Carbo-loading before a cardio session impairs the use of body-fat as fuel.
  • It shifts you from being a fat-burner to a carb-burner
  • However, because of this study, you can have the best of both worlds. The performance boosting effect of carbs combined with optimum fat burning.



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Journal of Physiology


  1. Fascinating study. I wish they had included a third group that consumed both solutions for comparison. I suspect the group that actually drank the solution would outperform the rinsers, but it would be nice to see where they fell on the spectrum.

    It’s worth pointing out that carbo loading is only necessary if you’re going really long and hard – i.e. if you’re a manner of endurance athlete. It drives me crazy when average-joe-who-wants-to-lose-weight starts using tactics from distance athletes and wondering why it doesn’t work.

  2. Today at the gym, I saw Mr. Cardio pedaling away in his fat burning zone sucking back a large bottle of Gatorade…BTW, it was Blue flavor, my favorite.

  3. What was the “carb rinse”? I’m starting to train for my first tri and I would like to know the actual ingredients for it. I apologize if this seems like a dumb question but I just want some info. And depending on my tri distance, would you even recommend something like this for a sprint tri? Thanks for reading,
    Guy trying to be healthy

  4. I would assume though that pretty soon your body would become wise to what your doing and would stop working on a ‘fat burning’ level, would infact slow down or you’d become irrationally hungry. Similar effects have been shown have they not when testing the difference between diet and full sugar drinks: the body thinks its getting sugar, it realises pretty soon that it has not had sugar, the cravings for sugar come back and with force.

    So maybe whilst this could be a short term idea to try, you’d better beware of the come-back-cravings!

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