Fasted Cardio

Article written by Amy Payne

To eat or not to eat: isn’t that always the question?  Well in the case of Fasted Cardio for fat loss, that is the question.  There has been much debate as to whether or not you will lose more fat while doing cardio fasted or performing cardio after consuming meal or 2 or 3.   

So what is Fasted Cardio, and what’s the point?  The idea behind fasted cardio  is, performing cardio in a fasted state prior to eating first thing in the morning, the calories you burn will be a greater percentage from fat, and lead to superior overall fat loss. So obviously, performing cardio after eating would be the flip side of the coin.  The drawback of  fasted cardio from several viewpoints is that your body is can be in a catabolic state after going all night without food and start breaking down hard earned muscle for energy when doing cardio prior to eating.  

In the Strength and Conditioning Journal, Brad Schoenfeld summarized data in a review of Fasted Cardio in a straight to the point no bullshit manner.  So now I know all you cardio queens and kings want the summary right? The green light to keep up your crazy cardio sessions running on no fuel.  Drum roll…Schoenfeld stated, fasting before exercise actually reduced the thermogenic response to exercise when compared to not fasting. What does this mean you ask?  This shows that eating before exercise actually enhances the calorie burning, (thermogenic) effect of exercise! 

In the International Journal of Sports Nutrition Exercise and Metabolism, Italian researchers took 80 healthy young males and put them through 2 separate workouts:

Workout A: 36 minutes of slow cardio at 65% maximum heart rate in the morning without eating 

Workout B: 36 minutes of slow cardio at 65% maximum heart rate in the morning AFTER a small meal 

Conclusion?  24-hours after the workout the participants had greater fat burning and calorie burning after consuming the small meal prior to the workout.  The scientists concluded that “fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable.”

Scoenfeld’s summary explained that Fasted Cardio indeed caused bigger release of free fatty acids than traditional forms of cardio. It does not, however, increase the rate of oxidation and thus, (drumroll) there is no significance difference in fat loss between traditional cardio and fasted cardio.  

Fasted, Non-Fasted, to each their own really, the bigger factor that people lose sight of is intensity of the workout.  This single factor is by far more important for fat loss than fasted or non-fasted cardio.  Bottom line if you can hold a conversation on the treadmill go faster!  If you look the same going into the gym as you do when you leave, push harder.  Try to incorporate HIIT training (High Intensity Interval Training) to your regular schedule a few times a week and see what happens.  Let’s be honest, cardio is a nasty 6 letter word, no one likes it.  However, I do believe it has its place in developing and maintaining an athlete’s overall condition.  


International Journal of Sports Nutrition Exercise and Metabolism (21:48-54, 2011).

Schoenfeld B. Does cardio after an overnight fast maximize fat loss? Strength and Conditioning Journal, 2011(33): 23-25. 

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