Fasted Cardio: Does It Actually Burn More Fat? - Jake Langham

Fasted cardio has been a topic in the fitness world forever.

The basic idea is simple: train before breakfast, when you haven't eaten overnight, and your body will rely more heavily on stored fat for energy.

And there's some truth to that.

But there's an important distinction between burning more fat during a workout and losing more body fat over time.

So, does fasted cardio burn more fat?

Yes — during the workout, generally.

When you exercise after an overnight fast, your body tends to use a greater proportion of fat for fuel than it does when you've eaten beforehand.

Research has also shown that repeated fasted endurance training can increase some of the enzymes involved in fat metabolism.

So the "fat burning" part isn't a myth.

The important question is whether that translates into greater fat loss over time.

Burning fat isn't the same as losing fat

Your body is constantly using and storing energy throughout the day.

If you burn more fat during your morning cardio, that doesn't automatically mean you've lost more body fat by the end of the day.

Your body can adjust its fuel use later. You might use a little more carbohydrate and less fat later in the day, for example.

Think of it this way:

Fasted cardio can change which fuel you use during the workout. It doesn't automatically change how much body fat you lose over time.

A study by Schoenfeld and colleagues compared fasted and fed cardio during a calorie-restricted diet. Both groups lost body fat, but there was no significant difference in fat loss between them.

So what actually causes fat loss?

Ultimately, you need to consistently use more energy than you consume over time.

When your body doesn't get all the energy it needs from food, it has to draw on stored energy.

Some of that stored energy comes from body fat.

That's what drives fat loss.

Your diet, total activity, resistance training, protein intake and consistency all matter far more than whether your cardio was performed fasted.

So is fasted cardio pointless?

No.

If you enjoy doing 30–60 minutes of easy or moderate cardio before breakfast and you feel good doing it, go for it.

There's nothing wrong with it, and there are some legitimate metabolic adaptations associated with exercising with lower carbohydrate availability.

Where it gets more interesting is when the session becomes much harder.

A 30–60 minute easy or moderate cardio session is very different from a 45-minute hybrid-style conditioning session involving running, sleds, ergs, burpees, carries, lunges, and repeated hard efforts.

As intensity increases, carbohydrate becomes increasingly important for producing high levels of work.

If the goal of that session is to perform well, rather than simply accumulate some easy cardio, fuelling beforehand may make more sense.

So, where does that leave us?

Fasted cardio can increase fat oxidation during the workout.

That doesn't mean it automatically produces more fat loss.

If you enjoy fasted cardio and it works well for you, there's no reason to avoid it.

For 30–60 minutes of easy or moderate cardio, training before breakfast can be a perfectly practical option.

For harder hybrid conditioning sessions, fuelling beforehand may help you maintain performance and produce higher-quality work.

Ultimately, fasted or fed is simply another individual training preference. Choose the approach that fits your goals, your session and what allows you to train consistently and perform well.

Fasted cardio isn't magic, and it isn't pointless. It's simply an option.

Read The Shoenfeld Study Here.