Fasted cardio was made popular in 1999 by American trainer, Bill Phillips. Bill claimed that a body in a fasted state has depleted glycogen (simplified carbohydrate) stores. As a result, the primary fuel for a workout would be fat.
Furthermore, the lower levels or insulin that are associated with fasted cardio are optimal for fat metabolism (Edinburgh RM et al. 2020).
This sounds exciting. It seems as though we can maintain the same calorie allowance, undergo to same exercise routine but shake off extra belly fat. It sounds too good to be true because it is.
All macro-nutrients have the same chemical structure – Carbon, Oxygen and Hydrogen. Protein also contains Nitrogen.
If we undergo a fasted cardio session which metabolizes fat, our body is lightly to metabolize glycogen later. What I’m trying to say is that your efforts will be canceled out (Horowitz JF. et al, 1999).
I suppose you’re thinking that this is a justification of a low carb diet. After all, if there’s little carbohydrate available, the body will continue to burn fat. Primo D et al. (2019) showed that there is no additional benefit in a low carbohydrate diet as far as body composition is concerned.
Read the following article to learn more about low carbohydrate diets.
A Case for Fasted Cardio
My regular readers will know that to lose weight, we must simply remain in a calorie deficit. However, there are circumstances where you may benefit from fasted cardio. If you don’t have much time in the day for exercise, maybe a quick workout before breakfast is your best option.
As I’ve stated in my article Healthy Breakfast Eating and Weight Loss, fasted cardio may also be beneficial for type 2 diabetics who struggle with postprandial insulinemia. A long term intervention involving exercise before breakfast may very well increase insulin sensitivity and improve glycimic control (Hansen D. et al, 2017).
The Final Word
If you don’t consume breakfast before exercise, it’s probably not going to benefit your body composition. In fact, you may not get the most out of your workout. Without fuel, you may reduce the intensity of your training.
On the other hand, this method may save you time or be an optimal strategy if you’re a type 2 diabetic.