Is Fasted Cardio Better For Fat Loss?


Does doing cardio on an empty stomach help you lose more fat? Is it better to go running on an empty stomach first thing in the morning, or later in the day? Is fasted cardio a myth? Let’s look at the facts and the evidence.

You’ve probably heard it before that fasted cardio, or exercising on an empty stomach in the morning, is much better for fat loss compared to exercising after eating?

Roll out of bed, haul on your sports gear, grab your trainers then hit the pavement before breakfast. Some claim, thisfar better for dropping those pounds compared to exercising later in the day.

But does it really make a difference in the grand scheme of things? Are there any benefits? Should you always train on an empty stomach? Doesn’t fasted cardio burn muscle? Let’s look at the facts.

Does Doing Cardio On An Empty Stomach Help You Lose More Fat?

Does Doing Cardio On An Empty Stomach Help You Lose More Fat?

The logic is that if you exercise on an empty stomach, you take advantage of low glycogen levels.

Glycogen is how carbohydrate is stored in your body. It’s mainly found in your muscle. A little is stored in your liver and an even smaller amount is floating around in your bloodstream.

The theory behind doing fasted cardio in the morning is that instead of using the stored carbohydrate (glycogen) as fuel, your body taps into your fat reserves instead.

Although this may seem plausible, the science actually shows that it doesn’t really matter if you exercise on an empty stomach or not.

The science actually shows that it doesn’t really matter if you exercise on an empty stomach or not. Click To Tweet

One study in overweight and obese woman showed that the impact on body composition and glycaemic control wasn’t significantly different between the fed and fasted groups.

Another in the Journal of the International Society of Sports Nutrition recruited 20, healthy females and split them into two groups. One group did fasted cardio for 3 hours per week, the other exercised after eating. The result? Both groups lost weight but there were no significant differences between the two groups either.

The researchers concluded:

…those seeking to lose body fat conceivably can choose to train either before or after eating based on preference.

When it comes to fat loss, physiologically, it always boils down to calories in versus calories out. It’s not dependant on what time of day you exercise, or if you do your cardio fasted or not. Because…

300 calories is 300 calories

Let’s imagine one day you decided to head out for a run at 6am on an empty stomach and burn 300 calories. The next day you do the same run, burn 300 calories but this time it was after work. On both days, when you go to bed, you’ve still burned 300 calories, regardless of what time you exercised. Make sense?

Your body doesn’t know, or really care, what time of day you decided to train. The main thing is to pick a time and type of exercise that you enjoy. You should also follow a routine that you can consistently stick to.

Also, it’s important to note that fat loss doesn’t just happen when you hit the gym or go for a run. There are 24 hours in a day when you can lose fat.

There are 24 hours in a day when you can lose fat. Click To Tweet

Your diet plays a the largest role in body composition and to get leaner you need to be in a calorie deficit which can be done through increasing calorie expenditure or decreasing energy input.

Does Fasted Cardio Burn Muscle?

Does Fasted Cardio Burn Muscle?

A moderate bout of fasted cardio in the morning before eating is unlikely to cause you to waste away.

One study did show that muscle can be used during exercise for fuel to a greater extent in fasted training compared to fed training. However, the results weren’t that dramatic and for most people, fasted cardio isn’t going to eat away all your hard work in the weights room.

Therefore, it probably isn’t something to worry about too much unless you’re going to the extreme and training for hours on end in a fasted state. That, probably isn’t a good idea!

Should I Eat Before Morning Cardio?

It’s really down to you but if you have the time to let the food digest, it’s probably a good idea.

With our online coaching clients, if they exercise later in the day, we usually recommend they eat a snack or meal 2-3 hours before exercising. It should contain a small amount of protein and some quality carbohydrates (here are some high protein meal ideas).

The carbohydrates before exercising can top-up your glycogen and actually increase training intensity. This can be beneficial and one study showed that eating some carbs before training actually increased fat loss.

Some folks drink green tea before training with the hope of increasing fat loss. Unfortunately, this isn’t going to do anything for you either.

[Related: Can Green Tea Actually Help You Lose Weight]

Are There Any Real Benefits Of Fasted Cardio?

Are There Any Real Benefits Of Fasted Cardio?

Tthere aren’t any significant physiological benefits of fasted cardio or running on an empty stomach in the morning, but that doesn’t mean that you shouldn’t do it.

Preference is the most important thing when it comes to choosing what time you train.

Some people simply prefer training on an empty stomach because they don’t like the feeling of food churning around in their tummy, but that’s their choice.

For others, they much prefer training later in the day with some more fuel in their system. The choice is yours!

The Round Up

A post shared by Scott Baptie (@scottbaptie) on

The evidence shows that fasted cardio doesn’t increase fat loss compared to exercising after eating or later in the day. Although popular in bodybuilding circles, working out on empty stomach in the morning isn’t something you need to be doing! It’s entirely up to you when you decide to workout. The best time is whenever it fits your routine, lifestyle and preferences.

Fasted Cardio, Is Better For Fat Loss & Burning Fat?

Scott is the owner and founder of Food For Fitness. He is a fat loss coach, speaker and fitness writer with a masters (MSc) degree in Applied Sports Nutrition.