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Training While Fasted

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I’ve always trained in the morning after a big breakfast. My thought process was simple; I’d be providing high quality fuel for maximum muscle building. There is at least some degree of truth to my methodology.

Recently, however, I’ve found that my larger meals consisting of five whole eggs, a giant sweet potato and several cups of black, organic coffee have not led to my best workouts. I’ve actually been feeling somewhat sluggish during my sessions. On my recent road trip, I sprinted before breakfast and found my head to be clear and my body filled with ample energy. Additionally, I was likely burning fat more efficiently, according to a study reported in the New York Times:

For one, as has been known for some time, exercising in a fasted state (usually possible only before breakfast), coaxes the body to burn a greater percentage of fat for fuel during vigorous exercise, instead of relying primarily on carbohydrates. When you burn fat, you obviously don’t store it in your muscles. In “our study, only the fasted group demonstrated beneficial metabolic adaptations, which eventually may enhance oxidative fatty acid turnover,” said Peter Hespel, Ph.D., a professor in the Research Center for Exercise and Health at Catholic University Leuven in Belgium and senior author of the study.

If you’ve been following the blog, you’ve likely seen our posts devoted to the value of trial and error. It’s certainly the way I learn best and how I encourage folks I care about to learn about training. I’m putting the philosophy into practice on this one. Tomorrow, I’ll be running my sprints before breakfast.

I don’t necessarily have a specific plan in mind. This experiment came about simply from an anecdotal feeling of sluggishness. The research, however, suggests that I could experience better muscle development and recovery from my sessions. From a study published in the European Journal of Applied Physiology:

…training in the fasted state, compared with identical training with ample carbohydrate intake, facilitates post-exercise dephosphorylation of eEF2. This may contribute to rapid re-activation of muscle protein translation following endurance exercise.

Contrary to my concerns about my body not having enough fuel to fire in an optimal fashion, training in the morning while still fasted may lead to more power. From the Journal of Strength and Conditioning Research on a study on cyclists:

In addition to aerobic endurance and anaerobic capacity, high power-to-weight ratio (PWR) is important for cycling performance… exercising after fasting overnight can improve a cyclist’s PWR without compromising endurance cycling performance.

I don’t know if a study on endurance athletes will apply to my sprints, but it is worth finding out. I’m not going to put a time limit on my trial. If I don’t have ample energy, I’ll go back to my old style. That result would represent the error, and I will have learned something. If I’m feeling strong, perhaps I’ll stick with it.

To science,

Kap

  • iain

    A couple of months ago I switched to hitting the gym in the morning Monday to Thursday due to commitments at work and my rugby team. I never feel hungry when I wake up so I naturally begin training fasted. I have felt no decrease in strength or energy during my sessions (if anything I have progressed) and have lost a bit of body fat with the change (I also tightened up on my diet). But the biggest change I have found is that I no longer feel sluggish in the afternoon. Before my head would start to nod about 3 o’clock but now my energy levels stay high throughout the day, despite waking up an hour earlier. I am definitely converted!

  • Joey

    In my experienvce doing cardio in a fasted state is great for dropping BF. Like you posted research supports this theory. As for building muscle or trying to improve strength a fasted state is not optimal. Research supports this theory also. So I think it really depends on your personal goals as to which theory you should follow. I follow those principles when working with my clients and it has worked quite well. My 2 pennies.

  • Msquared

    I have always felt stronger when I have had food prior to a workout…. But usually with an hour or so gap.

    • Kara Jackman

      I’m big on the hour gap too especially before tennis matches and try to apply the same for daily workouts. I don’t workout in the morning, but I know I need to eat in the morning because I wake up really hungry. I also have questions about hormone levels and their contribution when it comes to women. Would hormone levels effect the ability to burn fat and/or build muscle using the fasting methodology?

      Do hormone levels affect how we burn fat/build muscle, overall? I am a small-framed woman and find it hard to lose body fat, so these are just some of my musings. Thanks for the blog, Kap.

      • Joey

        Hormones will always play a role in how the body functions physiologically. So yes hormone levels will affect fat loss and building muscle. I’m no expert by any means but I can tell that for instance if a male has low testosterone he will tend to have more body-fat and less muscle in general. If you are worried about hormone levels you can always have your HCP/Doc draw a CBC.

        • Kara Jackman

          thanks!

  • highaltitudegirl

    I find this to be true for myself and my workouts, so much better before eating. At least 3 hours seem to be best for my performance. Gabe; love your blog by the way!

  • bill

    Trial and error, or listening to your body seems to be a sound approach. I suspect it’s not a simple, generic issue. What you eat, how soon you exercise, what kind of exercise, your particular body…all might come into play. Keeping a journal would probably yield significant data. The increased awareness created from keeping a journal could have an effect! Focusing on the journey instead of the destination usually works out pretty good!

  • Lee

    I have become accustomed to always eating a good size breakfast before working out because I don’t like how empty my stomach and head feel without eating foods. One thing I did mess around with was juicing before cardio bouts and that gave me plenty of energy to run sprint after sprint and also I was able to do longer conditioning as well without any crash or muscle fatigue. I only juiced before cardio and always crushed the eggs and greens before weightlifting days. When my stomach is empty lifting I get fatigued and lightheaded so I always have to eat prior. Also the best part about juicing was I was able to save the pulp and turn around and blend that into my post workout shake. I was juicing everything from berries and beets to celery, kale, spinach and ginger root. It was definitely beneficial for me to push through those high intensity workouts without having to take any artificial pre workouts.

  • http://www.Kelebekfusion.com Kelebek Beyaz

    It really depends on your body (speaking scientifically). I have a few friends who will only work out in a fasted state. I cannot do this as I have hypoglycemia (my blood sugar is the lowest in the morning) and when I have tried it, I passed out both times. I find if I have a small breakfast, I can get in my normal workout and even teach a two hour dance workshop. I feel very focused.
    As a scientist and reader of your blog, I am a big fan of trial and error. So again, it depends on your body, goals, and what works for you.
    Kelebek

    • http://kaplifestyle.com/ Stephanie St Amour

      So true, Kelebek.

  • Matthew D.

    My best workouts (since getting BACK at it) were this summer. I’d meet my buddy at the gym around 7:30-8 on an empty stomach. I always attributed this to just “being fresh.” My worst workouts have come since school started. 5:30 after a full day of class and practices led to feeling fatigue. Then there was the 5:00 AM workout where I actually dozed off on the flat bench between sets. Summer come quick, my friend.