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Does fasted cardio burn fat?

July 21, 2019

To build and tone muscle, you need a combination of resistance training and cardiovascular exercise. Resistance training takes care of the development of lean muscle mass (or massive gains) and positively impacts the metabolism while cardio helps to keep the body and organs healthy/fit and can be used as a tool to increase the number of calories burned to allow for the hard gained muscle to show through. This duo is how you achieve your ideal body composition.

What is fasted cardio?

Fasted cardio is performing a cardiovascular exercise on an empty stomach, usually done first thing in the morning as this is the only time you have had an empty stomach for a number of hours. In terms of the exercise being done, it’s exactly the same as your normal cardiovascular routine but you’re doing it on an empty stomach. You may find it harder than your normal routine as you do not have the food in your system to provide you with the vital energy needed to complete the workout.

Fasted cardio has become a method for improving one's physique because it forces the body to use fat instead of carbs for fuel. Yeah, that sounds great and it is but like everything else, there are pros and cons. Let’s discuss the pros and cons of fasted cardio.

Pro: Increased Fat Burn

Although just mentioned, increased fat burn is the reason why people turn to fasted cardio. When you wake up, the amount of stored carbs (glycogen) in the body is low since stores are used to keep glucose-dependent organs running as you sleep. As you may know, carbohydrates are the body’s primary source of fuel while the second is fat. Because little carbs are present to fuel physical activity first thing in the morning, the body taps into its secondary source.

Con: You May Burn Muscle

When the body is forced to tap into other fuel sources to conserve carbohydrate stores, you run the risk of burning muscle. Despite conflicting studies, researchers have found that fasted cardio significantly increases muscle breakdown. You know how we discussed fat being the secondary source of fuel? Well, muscle, or protein, comes third which isn’t what you want. If there aren’t enough fat stores readily available, the body will convert protein or break down muscle to provide energy. Lean mass takes work to build so you don’t want to force the body into a catabolic state.

Pro: Increased Nutrient Absorption

After fasted cardio, the body is hungry and muscles need to replenish glycogen stores since they’ve been running on an empty tank. A high protein meal should be consumed to kick-start the recovery process and the body could also do with some healthy fats to again replenish the body’s stores. Due to the high need for fuel, nutrients are better absorbed.

Con: Compromised Performance

With fasted cardio, there are limited carbohydrates present to fuel your efforts meaning you’re likely to work at a lower intensity. Although fat is the secondary source of energy, the process of converting fat to energy is slower than the mobilization of carbohydrates for fuel, meaning you will not be able to work at the same intensity as you would be able to when using carbohydrates as the primary source of energy.

Conclusion

Overall, fasted cardio is a method that could be incorporated into your training regime, but the impact it has on fat loss isn’t as significant as some may think. It is more of a short-term solution for those looking to burn extra fat during a bout of exercise instead of increasing their ability to burn fat. This is why those preparing for a fitness competition turn to fasted cardio rather than athletes with sights on long-term goals. A study in the Journal of the International Society of Sports Medicine that explored the body composition changes of fasted vs. non-fasted cardio training found no significant changes between the two groups of women in the study; and this concluded that diet is the key to fat loss and that training fasted/ not fasted has no major effect on body composition.