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What is Fasted Cardio & Is it Good for Weight Loss?


What is fasted cardio?


Fasted cardio means doing cardio workouts on an empty stomach, when your body is in a fasted state. For most people, this means first thing in the morning before breakfast, unless you practice intermittent fasting. Fasted cardio is popular with people who want to lose weight. It might tap into glycogen stores, but does it actually burn more fat than regular fed cardio?


Will fasted cardio burn more fat?


Fasted cardio is a topic that fascinates researchers, too. In 2014, a big study was published in the journal of the International Society of Sports Nutrition which looked at changes in body composition after four weeks of fed cardio or fasted cardio during a hypo caloric diet.


This study found that body composition changes were similar in the fed and fasted cardio groups (if calories were the same), and advised that people should choose to do cardio “based on preference”.


Is fasted cardio better than fed cardio?


Two years later, a systematic review and meta-analysis was published in the British Journal of Nutrition. This research looked at the effect of fasted and fed cardio on fat and carbohydrate metabolism (not just fat loss) and concluded that “aerobic exercises performed in the fasted state induces higher fat oxidation”.


What are the benefits of fasted cardio?


Research suggests that fasted exercise can lead to higher levels of fat oxidation during exercise, but this is not the same as fat loss. If fat loss is your goal, what are the perceivable benefits of fasted cardio?


Get it done early


Doing cardio first thing in the morning is a great way to start the day! And if you’re on a fat loss programme that stipulates you have to tick the cardio box, why not get it done early?


Save time


Fasted cardio might even save you time, because you can get up and get it done before your morning shower rather than having to fit in cardio at lunch or after work.


Habit stacking


Have you ever noticed that good decisions follow on from each other? This is called habit stacking. If you start the day with a fasted workout, you are more likely to choose healthier meals and activities throughout the day.


Mental motivation


Getting cardio done early feels great and will leave you with a sense of accomplishment which will motivate you to follow the rest of your fat loss plan.


Placebo effect


Sure, researchers don’t think fasted cardio leads to greater fat loss. But thousands of gym goers and bodybuilders all over the world would disagree. There’s no harm in it, so if it makes you feel good then go for it.


How long should you do fasted cardio for?


There is no time limit to fasted cardio, although common sense tells us it’s not smart to go and run a half marathon without eating anything pre workout. The risks of doing long fasted cardio sessions include muscle breakdown (catabolism), low blood sugar, and low energy levels. Since one of the big benefits of fasted cardio is time efficiency, aim to keep your fasted cardio sessions to 30 minutes. And don’t forget to eat a high protein meal with some carbohydrates post workout.


What are examples of fasted cardio?


What is the best kind of fasted cardio to do? Is HIIT or LISS better for fasted cardio? There are no right or wrong ways to do fasted cardio. Just as the research says, it comes down to preference, and this includes choosing cardio that fits your schedule. Here are 5 convenient types of fasted cardio you could do in the morning:


Fast walking – yes, walking is legit cardio and probably one of the easiest things to do in the morning. Drink some water, pop your earbuds in, and head out to get some fresh air.


Running – if you enjoy running, head out for 20-30 minutes at moderate intensity after drinking some water. What could be easier?


A workout class – booking into a 6am circuit class or CrossFit WOD is a great way to get your fasted cardio done. For higher intensity exercise, you could drink some BCAA to buffer muscle breakdown.


Indoor cycling – head to the gym or jump onto your own bike (if you have a turbo trainer) and bang out 30 minutes of steady state or intervals in the morning.


Erg/rowing – fasted cardio on the rowing machine is an easy way to focus on the numbers without needing to navigate any hazards of the outside world, especially during Winter weather.


Should I do fasted cardio every day?


Yes, you can do fasted cardio every day if you want to. After all, a lot of people go for a walk in the morning before breakfast. But do you have to? There’s no evidence that doing fasted cardio will accelerate your fat loss result when you’re dieting. It’s really important to balance sleep, energy, and motivation. If you find that fasted cardio energises you and help you make healthier choices during the day, stick to it. But if daily fasted cardio leaves you feeling exhausted, switch up your schedule so you get more rest.

Nicola is a specialist freelance copywriter for the fitness industry @thefitwriter