Fasted Cardio: What is it and How Does It Work?

Joe DynesBlog, Health & Wellbeing

fasted cardio feature

If you enjoy exercising before the sun rises or you are too busy to eat before heading to the gym, chances are you will have completed some fasted cardio. It is an exercise technique gaining many plaudits for the additional benefits that it can bring to your workout and this post will delve into how it works and whether or not science backs it up.

But, I here you ask, what is it?

The simple answer to this question is, “exercising when the body is in a fasted state,” and evidence from the British Journal of Nutrition shows that this type of exercise can burn up to 20% more fat than fed exercise.

When the body is in this fasted state and we exercise, we benefit from an increase in lipolysis (the process of burning fat). This is because body has no choice but to tap into stored sources of energy, such as fat molecules, to fuel the muscles and generate force as it cannot use any recently consumed energy.

In order to achieve this extra fat burn the body must be in a fasted state. However, this state doesn’t simply come when your stomach feels empty, as it takes around 8 hours of no eating for the body to enter into a fast.

This means exercise is being done when the body’s insulin level is at its low, baseline level and food is no longer being processed. This is an extremely important part of the theory as one of insulin’s vital roles relates to fat storage. Insulin inhibits the breakdown of fat and stimulates the creation of body fat, therefore, exercising while levels of this hormone are low means more fat can be broken down and used as fuel.

However, there is evidence to suggest that fasted cardio doesn’t work and that at best it delivers results that are comparable to fed cardio. One study in the International Journal of Sport Nutrition and Exercise Metabolism concluded that exercising in a fasted state does not increase fat loss and even recommends a light meal prior to exercise. Sadly, the body cannot be tricked into burning one type of fuel, namely fat, during a workout as energy systems in the body are a complex and dynamic system that depend on a wide range of variables.

“When the body is in this fasted state and we exercise, we benefit from an increase in lipolysis (the process of burning fat)”

Another question to ask is, can you push as hard during a workout when you haven’t eaten compared to when you have? High intensity training will not only burn more calories during your workout, it will also cause more calories to be burnt post workout and lead to a greater calorie deficit which in turn will lead to weight loss.

The important thing to take away from this post is that new health and fitness trends will always appear but one thing will not change – there is no magic formula or short cut to reaching your goals and success relies entirely upon hard work and taking care of the simple things such as pushing as hard as you can during training sessions, accompanying this with the correct nutrition and good levels of sleep.

Keep pushing,
Joe D

Joe Dynes

Personal Trainer at PGPT
With a varied sporting background that includes basketball, rugby and cross-country to name just a few, Joe’s passion for sport and exercise progressed him naturally from participant to trainer. Experience coaching CrossFit underpins Joe’s training style that focuses heavily on impeccable technique whilst still delivering interesting and highly varied sessions that will bring it your very best and help you achieve your goals.

Favourite film: Jarhead
Favourite food: Panang Curry

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