Should you fast before you workout?

Should you fast before you workout?


Fasted training is on the rise, with many people ditching their pre-workout meal and instead hitting up the gym on an empty stomach. But is it worth saving your avo on toast until after you’ve been to the gym or is it having a detrimental impact on our health? 

What is it? 

If you’ve not heard of fasted training before, it is when you train on a limited supply of carbohydrates. This means that rather than using carbohydrate stores for energy your body results to using fat. In theory, this then results in you burning more fat. 

Makes sense, but what does science have to say about fasted training? 

The Science 

A study conducted by the University of Bath revealed that fasting prior to working out did indeed result in favourable changes in fat tissue, in the sense that reliance on fat was increased and therefore more fat was burnt. 

However, don’t go giving up your pre-workout snack just yet, especially if you’re female. A study published in the Journal of the International Society of Sports Medicine revealed that there was very little difference in the body composition of those who fasted prior to their workout and those who didn’t.

 In fact, they argued it could actually have a detrimental impact on our health.

This is because our bodies need fuel to develop, grow and recover. Training fasted therefore means reducing that fuel, which could mean that it would take a lot longer to recover from your workout and slow down the growth of lean muscle mass. 

Why does this matter more if you’re female? 

It comes down to the hormone, cortisol (the stress hormone to you and me).

 If you’re a morning trainer pay attention! 

Overnight your body’s cortisol levels rise. Your morning bowl of cereal helps to bring it back to its normal level. If you skip this and head straight to the gym, your body continues to release cortisol. If your cortisol levels remain too high, you’re at risk of messing with your hormones

For guys, this isn’t too much of a problem. The result is an increase of testosterone, which helps to boost metabolism. 

For women, however, high cortisol levels can throw your menstrual cycle totally off and cause other health issues as a result. 

This is not to say never train fasted but if you do decide to train fasted, be aware that you’re unlikely to be able to perform as well as you do after a meal. 

Fasted training, therefore, might be something you do irregularly and not for every gym session. Before a fasted training session ensure that you are replenishing your body and giving it what it needs. 

Do you train in a fasted state or do you need your pre-workout meal to power you through? Let us know down in the comments. 


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