4 Crucial Reasons To Think Twice About Eating Carbohydrates Before A Workout

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Nutrition, Podcast

This article is Part 1 of a two-part series from Ben Greenfield on the benefits of carbohydrate restriction during training. If you have questions or comments, please leave them below!

You roll out of bed and glance at your watch. You've got a 12 mile run on-tap for the day, and limited time to get it in. Do you lace up and head out without grabbing a banana, bagel or handful of sports gels, or do you make sure you have sugar to consume before and during the effort?

If you're a good little endurance athlete, you probably raised your hand and said “Eat!”.

But the entire basis for posing a question like this is based on the fact that multiple research studies have proven that several components of your aerobic fitness are enhanced when you train with low levels of storage carbohydrate or low levels of carbohydrate intake during the exercise session.

Sorry, Wheaties, but it's true: you don't actually have to be a carbaholic to be an endurance athlete.

Now don't get me wrong: there is absolutely no argument that high-carbohydrate intake before an endurance exercise session can postpone fatigue and improve performance. So it's no surprise that the “gold-standard” recommendation from most sports nutritionists is to consume a diet that provides high carbohydrate availability before and during exercise.

But how superior is a high-carbohydrate intake to the polar opposite: eating nothing at all?

A study in the 2010 Medicine and Science in Sports and Exercise Journal suggested the answer to this question when it coined the term “train low, compete high” in response to results that showed untrained individuals achieving better training adaptations and aerobic capacity after 10 weeks of training with low carbohydrate availability, compared to subjects who had high carbohydrate intake before and during exercise.

Another study in the Journal of Applied Physiology showed that trained individuals who performed twice a day training sessions without eating for 2 hours after the first session (thus depleting carbohydrate stores with the first session) experienced a better ability to store carbohydrate, use carbohydrate as energy, and burn fat – with no loss in performance compared to a group that only trained once per day and ate carbohydrates afterwards.

Yet another follow-up study in trained cyclists performed high intensity interval training with no carbohydrate intake showed improved fat utilization and an increase in the enzymes involved in energy metabolism, again, with no loss of performance.

Finally, current research shows that when carbohydrate stores are depleted by almost 50%, there is evidence that there is actually increased stimulus for enhanced enzyme activity in skeletal muscle, which is a good thing, since it means you can more efficiently produce energy from fuel.

And what about eating carbohydrate during training?

Despite the handy sports gel chamber enhanced water bottles on those fancy new bikes, and the tray for your sports gels on the gym's treadmill, as long as the training session is not performed in a carbohydrate depleted state, and does not exceed about 2 and a half hours, there is no evidence to show that avoiding carbohydrate during the session will reduce performance, and there is research that actually shows quite the contrary – no loss of performance!

Whether any of these benefits are due to decreased carbohydrate use or increased fat use is unclear, but there are obviously benefits to going low carbohydrate before and during training.

In summary, if you restrict carbohydrates before, during or after training you may:

#1: Increase activity of the biological mechanisms responsible for building and repairing lean muscle tissue.

#2: Increase ability to preserve and ration valuable carbohydrate stores.

#3: Increase fat utilization during exercise.

#4: Increase the activity of the enzymes responsible for metabolizing carbohydrates during high intensity exercise, such as racing.

In Part II of this series, which will be available at http://www.rockstartriathlete.com on Friday, February 4, you'll learn exactly what happens inside your body when you restrict carbohydrate intake, and get 5 instantly practical ways to cut carbohydrates in your training and racing, along with the advantages and disadvantages of each approach.

If you have questions or comments, please leave them below!

Ask Ben a Podcast Question

27 thoughts on “4 Crucial Reasons To Think Twice About Eating Carbohydrates Before A Workout

  1. Varun Sharma says:

    For loosing weight we have to avoid carbs. If we consume carbs there is no effect of that.

  2. Hi Ben,

    I am a strength Athlete and I wished to understand if I can have Carbs post workout after which is around one in afternoon. I restrict carbs until I train, so morning light stretches, coffee, cold shower, then hard workout at 10:00 am. Lunch by 1. So can I have carbs, here ? With my protein meal. Then I will have carbs in evening again right with protein meal ? Will that be a carb meal ? Will it be same if I only run next day and don’t lift then ?

    Thank you 🙏

  3. Dominic Dawson says:

    Hey Ben I’ve been following a keto plan, but now im starting track I have only been eating vegetables for my carbs, and fats have come from cocconut oil, butter, olive oil, and fatty meats, but now im trying to achieve a 5 min mile but want to keep insulin low and carbs low for all the benefits is there a way I can use carbs to achieve my goal with minimal amount of carbs as possible, when do you recommend me eat carbs ,and what type of carbs should I eat.

  4. Tommy says:

    I don't eat high card breakfast unless I'm going to be out 2 + hours straight, AND, if I'm going to be > 80% of MHR. So with out reading the articles, I believe it. Hey Ben, can you talk about this on your next podcast?

  5. Fatman says:

    Interesting article. I am still eating my oatmeal in the morning, about an hour before I train. Eating too much kills my energy, not eating anything does the same; a small bowl of oats prepared with milk and honey always does the trick.

  6. scott says:

    i just saw an ad. on t.v. for uncle ben's rice. it's suppose to have all the nutreients of brown rice but have the taste of white rice. do you know anything about that?

  7. IOWied says:

    So Ben, what about the recovery drink taken within 20 min after my typical 1hr workout? Should I leave the carb sources OUT of that protein drink? The wisdom I got from you has been 3:1 carb:protein blend in order to help muscle recovery and prevent catabolizing muscle?

  8. Bill R says:

    Way to go with the footnotes!! Keep us up to date and in line with our workouts. Science is what it is all about and Ben, you are on the cutting edge. Thanks for all you do.

  9. WalkDMC says:

    What about eating afterwards. I am reading Art De Vany's new book The New Evolution Diet. He says not to eat an hour after exercise to give fat burning and growth hormones time to act before eating and thus secreting more insulin.

    1. I'm trying to get Art on the podcast, so stay tuned!

  10. scott says:

    if you followed this plan what would you eat? what if you go longer than 2.5 hrs.?

    1. It's pretty simple. Just include a session or two a week where you exercise in a fasted or semifasted state, or just do a long workout where you fuel with fewer calories than you normally would. You can still eat carbs. It's not a "plan", just a strategy.

  11. Brad says:

    Ben great article. I have just started the Zone eating proscription and hearing about lower carb intake being beneficial for exercise alleviates some fears. Thank you for your services.

  12. ricky says:

    you know ben, without knowing any of this, that is how i dropped from 235lbs to 165lbs when i first started exercising. i always worked out early in the morning and never ate anything before heading out.

  13. Kelcey says:

    I'm so confused . . .

  14. Miguel says:

    But you said in your book Holistic fueling that we should eat carbohydrates before workouts….

    1. I'd be a pretty poor nutritionist if I didn't pay attention to research. And it is becoming clear that you don't need to to eat carbs before *every* workout.

  15. nedL says:

    Hey Ben, any way you can post the details of your sources?

    1. Akerstrom TC, Birk JB, Klein DK, et al. Oral glucose ingestion attenuates exercise-induced activation of 5'-AMP-activated protein kinase in human skeletal muscle. Biochem. Biophys. Res. Commun. 2006; 342:949–55.
      Akerstrom TC, Fischer CP, Plomgaard P, Thomsen C, van Hall G, Pedersen BK. Glucose ingestion during endurance training does not alter adaptation. J. Appl. Physiol. 2009; 106:1771–9.
      Arkinstall MJ, Tunstall RJ, Cameron-Smith D, Hawley JA. Regulation of metabolic genes in human skeletal muscle by short-term exercise and diet manipulation. Am. J. Physiol. Endocrinol. Metab. 2004; 287:E25–31.
      Baar K, McGee SL. Optimizing training adaptations by manipulating glycogen. Eur. J. Sport Sci. 2008; 8:97–106.
      Bergström J, Hermansen L, Hultman E, Saltin B. Diet, muscle glycogen and physical performance. Acta Physiol, Scand. 1967; 71:140–50.
      Burke LM. Fuelling strategies to optimise performance-training high or training low? Scand. J. Sports Med. Science. 2010; 20:11–21.
      Burke LM, Hawley JA. Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Med. Sci. Sports Exerc. 2002; 34:1492–8.
      Churchley EG, Coffey VG, Pedersen DJ, et al. Influence of preexercise muscle glycogen content on transcriptional activity of metabolic and myogenic genes in well-trained humans. J. Appl. Physiol. 2007; 102:1604–11.
      Cochran AJ, Little JP, Tarnopolsky MA, Gibala MJ. Carbohydrate feeding during recovery alters the skeletal muscle metabolic response to repeated sessions of high-intensity interval exercise in humans. J. Appl. Physiol. 2010; 108:628–36.
      Cox GR, Clark SA, Cox AJ, et al. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. J. Appl. Physiol. 2010; 109:126–34.
      Coyle EF, Coggan AR, Hemmert MK, Ivy JL. Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. J. Appl. Physiol. 1986; 61:165–72.
      Creer A, Gallagher P, Slivka D, Jemiolo B, Fink W, Trappe S. Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle. J. Appl. Physiol. 2005; 99:950–6.
      De Bock K, Derave W, Eijnde BO, et al. Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. J. Appl. Physiol. 2008; 104:1045–55.
      Garcia-Roves P, Huss JM, Han DH, et al. Raising plasma fatty acid concentration induces increased biogenesis of mitochondria in skeletal muscle. Proc. Natl. Acad. Sci. USA 2007; 104:10709–13.
      Hansen AK, Fischer CP, Plomgaard P, Andersen JL, Saltin B, Pedersen BK. Skeletal muscle adaptation: training twice every second day vs. training once daily. J. Appl. Physiol. 2005; 98:93–9.
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      Hulston CJ, Venables MC, Mann CH, et al. Training with Low Muscle Glycogen Enhances Fat Metabolism in Well-Trained Cyclists (published online ahead of print). Med. Sci. Sports Exerc. 2010.

      1. Keller C, Steensberg A, Pilegaard H, et al. Transcriptional activation of the IL-6 gene in human contracting skeletal muscle: influence of muscle glycogen content. FASEB J. 2001;
        Lee-Young RS, Palmer MJ, Linden KC, et al. Carbohydrate ingestion does not alter skeletal muscle AMPK signaling during exercise in humans. Am. J. Physiol. Endocrinol. Metab. 2006; 291:E566–73.
        Ljubicic V, Hood DA. Specific attenuation of protein kinase phosphorylation in muscle with a high mitochondrial content. Am. J. Physiol. Endocrinol. Metab. 2009; 297:E749–58.
        McBride A, Ghilagaber S, Nikolaev A, Hardie DG. The glycogen-binding domain on the AMPK β subunit allows the kinase to act as a glycogen sensor. Cell Metab. 2009; 9:23–34.
        Morton JP, Croft L, Bartlett JD, et al. Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal muscle. J. Appl. Physiol. 2009; 106:1513–21.
        Nybo L, Pedersen B, Christensen B, Aagaard P, Brandt N, Kiens B. Impact of carbohydrate supplementation during endurance training on glycogen storage and performance. Acta Physiol. 2009; 197:117–27.
        Onywera VO, Kiplamai FK, Tuitoek PJ, Boit MK, Pitsiladis YP. Food and macronutrient intake of elite Kenyan distance runners. Int. Journal Sport Nutr. Exerc. Metab. 2004; 14:709–19.
        Pilegaard H, Keller C, Steensberg A, et al. Influence of pre-exercise muscle glycogen content on exercise-induced transcriptional regulation of metabolic genes. J. Physiol. 2002; 541:261–71.
        Steinberg GR, Watt MJ, McGee SL, et al. Reduced glycogen availability is associated with increased AMPKalpha2 activity, nuclear AMPKalpha2 protein abundance, and GLUT4 mRNA expression in contracting human skeletal muscle. Appl. Physiol. Nutr. Metab. 2006; 31:302–12.
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        Watt MJ, Southgate RJ, Holmes AG, Febbraio MA. Suppression of plasma free fatty acids upregulates peroxisome proliferator-activated receptor (PPAR) alpha and delta and PPAR coactivator 1alpha in human skeletal muscle, but not lipid regulatory genes. J. Mol. Endocrinol. 2004; 33:533–44.
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        1. and the primary source: From Exercise and Sport Sciences Reviews

          Carbohydrate Availability and Training Adaptation: Effects on Cell Metabolism

  16. Aaron says:

    Makes sense. So, I have an 18 miler tomorrow with 10 at marathon pace. Should I consume anything before and/or during the run?

    1. Not advised. But what you could do is go the first HOUR without fuel OR if you plan on consuming 300 calories/hr in the marathon, consume 150-200/hr during this training run.

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