Fasted Cardio: Myth or Magic?

Today, we will be talking about a practice many of you may be familiar with.  Most people who have been around fitness or have been keeping up on the trends have probably at least run across the term “fasted cardio”. Is it good for me?  Should I be doing it?  Let’s start by taking a look at the term.

So, what is fasted cardio?

Starting with the first part of the term “fasted”, we know that this refers to being in a fasted state. Most of us know that to mean we have not eaten anything.  If you want to get really fancy, “fasted” technically means to willingly abstain from food or drink, so yeah, not eating.  The second part “cardio” is obviously referring to the action taking place, some sort of cardiovascular activity.  

When we add the two together, we are talking about performing a cardiovascular exercise while having nothing in our tummies.  

Why would we do this?

Supposedly, it helps you lose fat faster. The idea is your body will break down stored fat to power your workout instead of using food.  Technically true, but it’ also not correct.  When performed correctly, fasted cardio should not be very strenuous. Therefore, the need for the body to seek out stored energy is very low.  You probably aren’t going to break down more fat cells than doing normal cardiovascular work at the same intensity.  What fasted cardio does for you is allow for a preemptive strike at your metabolism. Getting a little extra calorie burn in during your day! 

If you are performing fasted cardio, most of the time it is being done early in the morning before your first meal.  Getting the metabolism revved up early and burning some extra calories is a great way to lose weight but not for the reasons you may think.  What fasted cardio really does for you is it allows you to consume the maximum number of calories while still losing fat.  When you put your body in an early calorie deficit, you have some wiggle room to consume a bit more food later. If you are performing fasted cardio in the morning, going about your day, then lifting in the afternoon or evening, you have a better chance burning more fat from your regular exercise program.  We can dive more into that science if you want, but let’s keep it simple for now!

Okay but should I do it?

Unfortunately, like most things in health and fitness, the answer is pretty unsatisfactory.  The real answer is kind of both good and bad.  To make it simpler, here are a few easy rules to follow:

  1. Fasted cardio should be performed at a relatively mild intensity if performed at all (think steady state cardio, brisk walk, maybe at an incline)
  2. Fasted cardio bouts should be relatively short. Try not to exceed 30 minutes.
  3. Fasted cardio may be appropriate if your main goal is body composition, improving the ratio between muscle and fat tissue.
  4. Fasted cardio is NOT advised for anyone who requires strength and/or power for their job or sport.

If you would like to start adding fasted cardio to your routine, I would advise converting it into more of a “semi-fasted cardio”. Consider consuming some BCAA’s and no more than 10-15 grams of simple carbs.  This would still put you in the necessary calorie deficit to potentially improve body composition. It may also ensure that the fasted cardio doesn’t turn catabolic, meaning eating away at that hard earned muscle! 

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