Fasted Cardio

Fasting is a mysterious, terrifying subject for most people. Despite its purported health benefits, the idea of not eating for extended periods of time scares most people living in western society. Truth be told, it isn’t all that bad. It’s fairly easy for most people to block off a window or 12-16 hours a day without eating, allowing them to reap many of the rewards.

Throw in any type of physical activity while in a fasted state and you can pull in even more rewards.

What is Fasted Cardio?

Many people use the terms “Fasting” and “Intermittent Fasting” interchangeably, but they have distinct differences:

Fasting = Extended period of time without consuming many/any calories. Usually for religious or cleansing purposes. (Consuming under 500 calories in a 24 hour period can be considered a ‘traditional fast’ under most definitions).

Intermittent Fasting = Fasting for a specific period of time, on a regular schedule. Usually for dietary purposes. (Example: 8 hour eating window, 16 hours no calorie intake for days on end). If you want to learn more about IF, please check: here.

In today’s world, it is incredibly rare to find someone who is actively doing either of them, especially outside of the fitness or religious worlds. However, both, traditional fasting and intermittent fasting, are incredibly useful tools that shouldn’t be avoided during your fitness journey.

For those of us who are already active, adding in cardio while on a short duration fast can bring new challenges for you to overcome.

Calorie Deficits

While they are not the same, fasting and calorie deficits generally go hand in hand. In fact, a lot of people fast so that they can reach into a calorie deficit, and thus lose some extra weight/fat mass. Staying in the negative calorie arena has all sorts of benefits, from mental perks to physical changes in bodily makeup and function.

In order to be in a calorie deficit (also known as a cut), you need to know what you are eating, so you generally need to track your consumption. Calorie counting, while monotonous and irritating, works. In fact, it is pretty much *the* only proven way to lose weight without surgical means, other than just not eating. The formula is simple:

More calories in than out = Weight gain.
More calories out than in = Weight loss.

Usually, people working on a cut don’t go too far beyond a 500 calorie deficit below their maintenance level. Anything further for extended periods of time and you will start losing lean mass alongside fat mass. Staying within that range forces your body to use its energy stores to power your body without you feeling too sluggish.

Cardio on a calorie deficit is still going to provide you with some of the same benefits (and drawbacks) that you would from fasted cardio.

It Doesn’t Sound Like Fun

Truthfully, it can be pretty miserable the first few times you try cardio either in a somewhat fasted state or while on a prolonged calorie deficit.

At first, our bodies aren’t used to working hard without all the energy running through our bloodstreams brought about by digestion. Since we don’t have all the energy during a fast or while on a deficit we would on a full stomach, we probably won’t hit a PR. That’s OK, though. It’s part of the journey of learning about your own body and how it works.

Our bodies are amazing and they adapt pretty quickly, always learning how to function in different ways.

There are a ton of benefits to fasting in general, but when it comes to fasted cardio, or cardio on a deficit, a few pretty amazing things happen:

1. We Dip into Fat Stores Easier

Usually, during cardio we rely on glucose coursing through our veins to power our bodies. When the source of that glucose is taken away, or restricted, our body runs out. That causes our bodies to dip into our fat stores much quicker, and use what we have stored away instead.

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2. We Can Shatter Mental Barriers

You never really know how tough you are mentally until you hit a proverbial wall. Fasted cardio can put you at that wall pretty quickly. When you are feeling tired faster than normal, will you push through it? Or will you quit?

3. We Rise Stronger Once the Deficit/Fast is Over

Performing with sub-par levels of energy teaches your body how to do more with less. Once you are off of a deficit or fast, and back to a normal level of calorie consumption, your body will be supercharged. Your energy levels will skyrocket.

Won’t I Lose Lean Mass?

Not if you are eating correctly. A fasted state forces your body to use the energy stores it has on hand in the form, usually fat. Tapping into those stores causes you to essentially burn away your fat deposits because it has no other energy floating around at the time.

Now, the naysayers will tell you your body doesn’t discriminate and could tap into ANY fuel source (muscle included). That’s true, but if you are otherwise following a good diet with adequate protein, your impact will be minimal. Yes, that includes even while you are on a calorie deficit.

If you combine adequate protein with making sure that you stay no more than 500 calories below your maintenance calorie level, you can be almost guaranteed to keep an overwhelming percentage of your hard earned gains.


The idea of exercising while restricting calorie intake is a hotly debated topic, with various groups and organizations taking either side for or against it.

Obviously, if you are on a full water fast for days on end, you should not try to do much other than exist until you break that fast and return to somewhat normal eating. Doing anything else can put you in unnecessary risk.

Make sure that you check with a doctor before you jump into any fasting. Period. Some people simply cannot do it for medical reasons.

Let Us help You Out

At CONDITIONerd we are here to help you achieve better physical and mental health through exercise. Check out the plans we offer to our customers and see if you could benefit from working with our team. And if you have questions, you can always contact a CONDITIONerd team member

Personal trainers, like those found here, can help guide you on your pathway towards reaching your fitness goals, whether that is getting bigger, stronger, faster, more lean, or just generally feeling better.

We can get you setup with a periodized workout plan, supplement information, and advice on nutrition to help you reach your goals.

The only thing you need is some motivation and a willingness to change some old habits.

Get into contact with us to find out what membership is right for you. In a CONDITIONerd program, you’ll be surrounded by others who can help you to get where you want to be.

Generally, our clients start to see some pretty awesome changes in 2-3 months time, some sooner.

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