Fasted cardio, basically working out on a completely empty stomach, has taken over the fitness world. Even celebrities like J Lo have joined the fray, showing you how popular this training technique has become. The question now is, is fasted cardio the best type of cardio for weight loss? Is it safe? And what are the benefits of fasted cardio? We answer all these questions today and so much more.

What Is Fasted Cardio?

Fasted cardio means working out after not eating for a couple of hours. Typically, according to science, your body is in a fasted state after 8-10 hours of not eating. Naturally, for most people, fasted cardio would occur the first thing in the morning.

When exercising in a fasted state, your liver and muscle tissues are basically glycogen depleted. Glycogen is how your body stores carbohydrates and the body needs carbs to fuel the brain and high-intensity workout.

You’ve probably already done fasted cardio without even realizing it. If you woke up early and went for a quick morning jog without having anything to eat, that was fasted cardio. The top reason fasted cardio is catching on like wildfire is its versatility and free-ness.

It works for any type of workout, whether it’s on your yoga mat, treadmill, or peloton. We must state though, to enjoy the full benefits of fasted cardio, you must maintain proper nutrition, stress management, sleep, and rest.

Plus, it’s not a one-size-fits-all type of workout. Some people simply can’t work out without breaking the overnight fast with a nutritious breakfast. And that’s OK. The main aim of achieving your fitness goal is to find a routine that works for you, not torturing yourself, especially if something is not working for you.

That said, the following groups of people should avoid fasted cardio:

  • You have an eating disorder
  • You have diabetes
  • You are pregnant
  • You have low blood pressure
  • You’re a teenager or child
  • You have an adrenal-related medical condition, such as Addison’s disease

Is Fasted Cardio Safe?

For the most part, yes, you can safely incorporate short or moderate-length steady-state fasted cardio sessions into your workout routine. However, it may not be advisable for an extended period of time or engaging in high-intensity exercise.

You risk developing certain side effects like low blood sugar or dehydration, which can cause dizziness, lightheadedness, shaking, or even passing out.

What Are the Benefits of Fasted Cardio?

So, are there any benefits exercising on an empty stomach?

Fat Loss

Well, according to research, when your body is depleted of glycogen, it will look for alternative fuel sources. Within the first few minutes of starting a fasted workout, the percentage of fat you would burn is slightly higher.

A study published in the British Journal of Nutrition found that people who ran on a treadmill in a fasted state burned 20 percent more fat than those who ate.

Another study published in the Journal of Applied Physiology found that people who consistently trained in a fasted state for over the course of six weeks exhibited more endurance improvements than those who ate before working out.

But there’s a caveat. Training in this state will not only feel like extra work, your body may also break down muscle mass to provide the fuel needed for working out. Plus, some studies suggest there’s a very modest increase in the amount of fat burned as fuel.

Therefore, don’t let fasted cardio be the be-all and end-all when it comes to sustaining your fitness goals. Try incorporating other forms of workouts like resistance and strength training exercises. More importantly, maintain healthy nutrition and sleep.

Improved Performance

Endurance athletes may benefit more from fasted cardio in terms of performance. According to studies, training in a level two fasted state may help boost performance. Level two fasted state is when you’ve depleted your muscle glycogen stores and deliberately not replenishing them. An example is exercising the entire week and minimizing your carbohydrate intake during that time.

Most users fall into level one fasted cardio where the liver is low on glycogen, but the muscle glycogen stores are still decent. Cutting out carbs from your routine and engaging in high-intensity exercise should only be left to professionals.

For endurance athletes, training while muscles are glycogen depleted encourages the active muscle tissue to rely slightly more on fat and a little less on carbohydrates as the fuel source. This helps them preserve glycogen stores until after the race, giving them an edge over their competitors by allowing them to run faster for longer.


If you work out on an empty stomach, you save time that could otherwise be spent preparing, eating, and digesting a meal. For fasted cardio, all you need to do is get up, get dressed and get on with it.

However, efficiency shouldn’t be your main motivator. Health should come first.

Effective for People with Sensitive Stomach

For some people, working out after eating can feel uncomfortable. So, exercising before eating (hence, fasted cardio) can make them feel lighter and more agile. It’s also a great option for those with a sensitive stomach.

What to Eat After Fasted Cardio?

Like we mentioned earlier, it can have some side effects like lightheadedness and dizziness. The most important thing is to listen to your body and know when to stop. Make sure to drink plenty of water throughout the workout, as this may impact the way you feel.

The rewarding part about completing your fasted cardio is the food. Chances are you’ll be more hungry and ready to pound on any food that comes your way. But eating smarter is the way to go.

Your best meals are those rich in nutrients, with a balance of protein and carbohydrates. Think protein pancakes, Greek yogurt with overnight oats, eggs on toast, porridge, or cereal.


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