Woman shows the benefits of fasted cardio

Fasted cardio benefits

5 min read


07 Sep 2023

Grab your cheat sheet

  1. What is fasted cardio?
  2. Does working out on an empty stomach promote fat loss?
  3. What effect does fasted cardio have on muscle mass?
  4. I really want to do fasted cardio but I’m struggling with my energy levels?
  5. Should I try fasted cardio workouts?

If you’ve been working out for a while and aren’t seeing the results you would like, you may have started looking into ways to squeeze more juice out of your workouts.

Fasted cardio is commonly recommended as a way to torch fat and help you shed the pounds.

So what is fasted cardio, exactly? And does it really increase fat loss?

Let’s find out.

What is fasted cardio? 

Fasted cardio workouts involve taking part in cardiovascular exercise (running, cycling, HIIT etc.) on an empty stomach or after an extended period of fasting. 

Sounds tough? It can be. But as we all know, losing weight is never an easy process. 

Most people do their fasted cardio first thing in the morning. We naturally fast while we sleep, so this doesn’t require us to do any additional fasting before their workout.

Don’t have time for morning workouts? You can do fasted cardio at other times of the day, but you’ll have to skip meals to ensure you’ve fasted your body for several hours beforehand. 

If you’re on an intermittent fasting diet, you can perform your cardio workouts towards the end of your fast.

Does working out on an empty stomach promote fat loss?

The theory behind fasted cardio is that you’re basically exercising while your body has depleted its glycogen stores. 

During the night, your body uses up its glycogen stores for energy. So when you wake up, your glycogen levels are lower.

Woman running on road to get cardio

Glycogen is our body's go-to energy source when we exercise without fasting. If we don’t have any glycogen, our body may use our fat stores as an energy source instead. So, many believe that fasted cardio can increase our daily fat burn.

But, others argue that overall we still burn the same amount of fat throughout the day. 

We’re more likely to use our glycogen stores later in the day, and will make less use of our fat stores. Some studies suggest that completing cardio in a fasted state has no significant benefit over completing it in a fed state.

So, what does work?

The only way to make sure that you lose weight is to create a calorie deficit: you have to burn more calories than you eat.

A healthy diet and keeping active throughout the day by walking more and getting up from your desk regularly is the key to consistent and sustainable weight loss.

The benefits of fasted cardio

Many people love working out first thing and don't simply do it to burn fat. Here are some of the other benefits fasted cardio:

  • Some people report a heightened mental focus during fasted workouts
  • Exercising first thing can help you feel energized the day ahead
  • You’ll feel a sense of accomplishment for having already done your workout which can really boost your mood
  • After work, you can just kick back on the couch, knowing you have already got your workout in. And, relax
  • Is fasted cardio safe?

On the whole, waking up and heading out for a job of hopping on the stair-master is perfectly safe for mostly healthy adults, as long as you drink plenty of water before and during the workout. Being hydrated is vital for exercise at all times of the day.

Pure water for good hydration

But, some people do experience dizziness or sluggishness working out before their breakfast. 

So, it’s good to question the quality of your workout. If you feel that your energy levels are too low to perform at your best, then having some food before your workout will likely improve your overall health and fitness in the long run.

You’re at a heightened risk of having low blood sugar during a fasted cardio workout—so it isn't recommended for anyone with diabetes or any other conditions that affect their blood sugar levels.

What effect does fasted cardio have on muscle mass?

Those of you who are trying to tone up or build muscle may be worried about the effects of fasted cardio on your muscle mass. 

During exercise, a process called muscle catabolism can take place.  This is where your body burns muscle protein to help fuel your workout. 

The best way to avoid muscle catabolism is to ensure you’ve eaten a good balanced meal with both carbohydrates and protein a few hours before exercising.

Fasted cardio can put you at greater risk of muscle catabolism. You’ll still lose weight, but unfortunately some of that weight could be muscle. 

Muscle mass has a big impact on your overall body composition and having more of it can help you keep burning fat even when you aren't exercising.

Prolonged or high intensity fasted cardio sessions put you at a higher risk of muscle catabolism. 

FYI: If your goal is purely to build muscle, we wouldn’t recommend fasted cardio at all. If your goal is weight loss and you find fasted cardio is really working for you, here are some things you can do to help prevent muscle loss:

  • Opt for a shorter activity e.g. 30 minutes rather than an hour
  • Avoid high-intensity workouts
  • Eat a healthy dinner the evening before with plenty of carbohydrates and protein
  • Eat a nutritious, healthy breakfast right after your workout
  • Get plenty of protein throughout the day

I really want to do fasted cardio but I’m struggling with my energy levels?

If you’re struggling with your energy levels or feel you aren’t making the most of your workout at any time of the day, we do have a great product that can help you smash your workout goals: PhenQ

Most weight loss pills target only one element of your weight loss, but PhenQ has it all. 

Two of its benefits include: 

  • Helping you burn stubborn fat
  • Maximizing your energy levels

This body-boosting double-threat ensures that your fasted cardio sessions really pack a punch.

Should I try fast cardio?

Ultimately, the most effective approach to exercise is to do it at a time that fits in with your schedule—and when you can be consistent. 

If you struggle with time or motivation first thing in the morning but enjoy sweating off the day at 6pm, then stick to evening exercise.

If you enjoy plenty of space and time to relax at the end of the day, give morning or lunchtime exercise a go.

Level up your workouts with PhenQ

Whenever you exercise, PhenQ is your perfect diet and workout buddy. It will help you feel full of energy for all your workouts, and reduces hunger and cravings throughout the day.