Cardio Workout | Fasted v Unfasted


Fasted Cardio vs Non-Fasted Cardio

First and foremost, let’s introduce fasted cardio and ensure we are on the right track when we are discussing it. Many people will post on social media that they are doing a fasted cardio session yet using BCAA’s, Caffeine and Carnitine. This would defeat the object of doing something fasted and is often looked upon as being ‘semi-fasted’. However, there really isn’t any such thing as being semi fasted as you have either not consumed anything or you have.


Usually, people keep fasted training to aerobic workouts due to resistance training requiring much more energy which would be provided through nutrients consumed in the diet. It is mainly used in the attempt to lose body fat and this is a method that has been proven to be a difficult solution to fat loss, not impossible, difficult.

“In otherwise healthy normal weight males, running for an hour on a treadmill at 70% VO2 max compared to either fasted or after a standardised test meal (30% daily energy intake and mostly carbohydrate) noted that fed exercise suppressed appetite to a greater degree than fasted (both more effective than control) but there were no significant differences in whole-day food intake.”

Why Should I Fast?

Fat loss is based on a calorific deficit and therefore doing a fasted cardio session in which will actually increase hunger compared to that of a non-fasted session. This would make dieting much more difficult. If you are focused on a calorie deficit then you are to make life much harder when trying to resist over-eating as appetite suppression would not be as effective.

There are however arguments for fasted cardio sessions, although there are not many physical advantages, there are phycological benefits. The simple fact of someone simply feeling great in the morning after their low-intensity cardio session where they can mentally prepare for the day and feel as though they are in a better frame of mind when it comes to their health and fitness goals.

cardio training

The Truth

The real answer to this question is that if you enjoy doing fasted aerobic sessions and you feel it offers an advantage to the way you train and diet then by all means go ahead and do it, however if you are someone that is only doing it because you have been told it is the only way forward with fat loss then I can assure you that the pain you suffer waking up and being hungry through a sweaty and boring cardio session isn’t actually necessary and doing cardio either after breakfast or after your workout later in the day will make no physiological difference.

If you are looking for a strength increase, fasted training simply will not cut it, you are much more likely to improve your strength by being fed and then going into your resistance workout.

In a sub-maximal exercise, there may be no differences at all between fasted and fed training. During maximal exercise attempts (which may include intense resistance training or high-intensity interval training) being fed with carbohydrates appears to be more beneficial than fasted training for the purpose of enhancing adaptations to training.

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Faye Reid

Faye Reid

Writer and expert

Faye has a MSc in Sport Physiology and Nutrition, and puts her passion into practice as goal attack for her netball team, and in competitive event riding. She enjoys a pun, and in her spare time loves dog walking and eating out.