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Fasted Cardio: Why You SHOULD Be Doing It To Lose Fat Faster

by Jeremy Ethier - May 12, 2019

Should you do fasted cardio to lose fat faster? How do you do it for the best results? Find out the answers and more in this article.

If you want to lose fat as fast as possible, then it’s often wise to include some form of cardio in your routine to speed up the process.

But, to lose fat even faster, many suggest performing your cardio on an empty stomach.
fasted cardio benefits
Or in other words “fasted cardio” often first thing in the morning.

And this is something I’ll often personally do as well especially as I get leaner.


Well, let’s start out by discussing what fasted cardio is in the first place.

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What Is Fasted Cardio?

Simply put - fasted cardio is any cardio session that's performed after a long period without ingesting any food. For example, after waking up first thing in the morning you'd be in a "fasted state" since you have yet to eat anything.

This is when your insulin levels have dropped to quite a low level, which has various implications on fasted cardio and its effect on the body.

How Does Fasted Cardio Work?

Let's start by covering why exactly fasted cardio got so popular in the first place and clear up some of the common misconceptions people have around it.

The basic theory with fasted cardio being superior for fat loss is the fact that research has shown that :

When exercising in a fasted state your body preferentially burns more fat for energy since your insulin and glycogen levels are low during this period.

Whereas when you eat before you exercise, your body tends to preferentially uses more carbs and less fat as energy when compared to fasted cardio.
what is fasted cardio
And this is mainly what led people to believe that performing your cardio in a fasted state would speed up fat loss to an even greater degree. Enabling you to get a six pack in the fastest way possible, right?

The Truth About Fasted Cardio

Now although it’s true that you burn more fat during a fasted cardio session...

...it’s vital that you take into consideration the post exercise period and what happens to your body after the session.

Because research has shown that although you may have preferentially burned more fat during the fasted cardio session...

...your body eventually compensates for this by burning more carbohydrates for the rest of the day.
benefits of fasted cardio
So by the end of it, you’ve essentially burned the same amount of fat as you would have had you eaten before your cardio.

And this was proven in a recent 2017 systematic review and meta-analysis on the topic.

The researchers found that performing cardio in a fasted state had no superior fat loss effect when compared to performing cardio in a fed state.

As it’s the calorie deficit at the end of the day that’s the overriding factor.

And although as I’ve stated in the past, fasted cardio may be particularly beneficial for burning stubborn fat...
...this is only applicable to very lean individuals and has yet to be proven in human studies.

So why exactly is it that I’d actually recommend trying out fasted cardio?

Well, for a couple reasons.

How Fasted Cardio May Help You Lose Fat Faster

Although fasted cardio doesn't provide any magical direct benefits to losing fat faster...

...there are various indirect benefits of fasted cardio that make it worthwhile for you to at least try out.

Fasted Cardio Benefit #1: It Makes It Easier To Eat At a Calorie Deficit

First off, it often makes it easier to eat at a calorie deficit.

By skipping your pre-cardio meal, or breakfast, your day’s eating window will now be shortened as a result.

This can make it easier when dieting since your meals are now closer to each other in the day.
fasted cardio workout
I find that this alone helps a lot in terms of appetite suppression and preventing excessive snacking throughout the day. And for many, these subtle changes will actually lead to a lower daily calorie intake.

Multiple papers have proven this as well.

For example, a recent 2019 study from the Journal of Nutrition compared the daily calorie intake in healthy male subjects who performed their cardio either in a fasted state or with breakfast prior to their session.

They found that the fasted cardio group ate on average 400 calories less than the fed cardio group!
empty stomach cardio study
This enabled the fasted group to achieve a calorie deficit by the end of the day which the fed group failed to do. And this alone, if repeated daily, would on average lead to almost a 1b of extra fat loss every week.

Fasted Cardio Benefit #2: It Can Be More Practical

Another great benefit of fasted cardio is that for many people it’s just more practical to do.

Getting it done first thing in the morning can not only help get your day started and boost your mood and productivity for the rest of the day. But I find that it helps with consistency as well.

As leaving your cardio for later on in the day makes it more likely that you’ll find some excuse to skip it and push it off to the next day.

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How To Do Fasted Cardio

Now as for what your fasted cardio routine should look like, although this will vary for everyone, I’d suggest sticking with the following general guidelines:

  • Stick to mostly low to moderate intensity cardio. Incline walking, light cycling, stairmaster, and so on are all good examples.
  • High intensity cardio sessions and interval training is fine as well but should be used sparingly. This is because fasted HIIT workouts cause more muscle damage, deplete your muscle glycogen to a greater extent, and can negatively affect your weight lifting workouts if you’ll be training later on in the day
  • Keep your fasted cardio workouts less than an hour long. This just helps prevent any potential muscle breakdown from occurring and prevents your performance from being negatively affected. Which research shows begins to occur in sessions lasting over an hour.

What To Eat After Fasted Cardio 

Now as for what to eat after your fasted cardio workout...

It will depend on the intensity and duration of your training as well as whether you'll be working out again later on in the day.

  • If you performed a low to moderate intensity session that was under an hour long, simply have a meal or shake containing adequate protein (at least ~20g) afterwards. Carbs are optional but not needed since you haven't done much to deplete your glycogen stores. However they can be beneficial if you will be lifting weights later on in the day in order boost your glycogen stores. Post-workout meal timing is not crucial in this case.
  • If you performed an intense HIIT cardio workout, then in this case you'll want to again ingest adequate protein afterwards but pair that with some fast digesting carbs (at least ~30-40g). This is especially important if you'll be lifting weights later on in the day, since you'll want to ensure your muscle glycogen levels are topped off during that workout. Timing is also more important in this case and the meal should be eaten within an hour or two following your workout.

The Takeaway For Fasted Cardio

To sum the article up, here are the main points to keep in mind:

Although fasted cardio doesn’t seem to provide any magical fat loss effect, it may be beneficial for you for the reasons previously discussed.

But all in all, you need to choose what you’ll be most consistent with and adhere to week after week.

Because at the end of the day, getting the work done and consistently achieving a calorie deficit through your fat loss diet and training is what’s most important.

 How To Incorporate This Into Your Routine

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Fasted Cardio: Why You SHOULD Be Doing It To Lose Fat Faster