If you've ever wanted to lose body fat but didn't quite understand how to approach it, I'm sure at one point or another you've gone straight to Google to figure out how to get the job done. Upon searching time and time again, you may have learned about certain forms of cardio such as steady-state cardio, high intensity interval training, as well as fasted cardio.
Many humans have a tendency to take the short and easy route a lot of the time. It's relatively painless, and requires very little effort, comparatively. In this article, I want to discuss the potential (keyword: potential) benefits of fasted cardio, as well as the consequences if not executed correctly.
SO YOU WANT TO LOSE FAT FAST
Don't we all? Hitting any sort of goal in an extremely short amount of time would be great, but that's just not how the world works, nor do our bodies. Losing fat is a slow process that needs to be done with consistent macronutrient tracking, clean eating, and patience. But, there HAS to be a way to speed it up, right? Well, yes and no. There are a lot of factors that go into fat loss during cardio sessions such as prior food intake, current well-being, genetics, etc.
There are rumors out there that fasted cardio can actually help you target fat loss quicker because the body is in a fasted state after you've slept, thus it has no choice but to use stored fat. This is true, BUT only under certain circumstances as well as precautionary measures that must be taken in order to avoid the one thing we don't want: using muscle tissue as fuel.
FIRST, SOME SIMPLE SCIENCE (kind of)
In order to transition into the necessary steps to almost guarantee fat loss, allow me to quickly discuss how our bodies operate under these conditions. Believe it or not, our bodies are much smarter than we think they are. They can adjust to certain environmental and behavioral situations without us even realizing it. It's quite fascinating. So what does that mean for fitness? Well, it means that our bodies are quick to enter survival mode (where it wants to hold on to a certain amount of fat), so at a certain point it will hold on to body fat and start using muscle tissue as fuel. When performing fasted cardio, our goal is to trick the body into thinking that it's not in survival mode, and it's free to use whatever fat stores it has for fuel.
SO HOW DO WE TRICK THE BODY?
When you wake, your body has nothing to work with. It's been feeding off of practically nothing for the past 6-8 hours. So, we must give our body something in order for it to feel like it's not in survival mode so it will utilize fat stores. Did you catch that? "Fasted" cardio that works isn't actually fasted cardio. Sure, your body has less to work with because you haven't eaten as many calories, but it must have some sort of carbohydrate to work with. This is because the intensity of the training can outweigh the body's ability to utilize fat stores as fuel. So at some point during the fasted cardio session, your body says away with the fat and on to the muscle.
There are studies performed that say those who perform cardio on an empty stomach are more prone to loss of muscle tissue over time compared to those who consume carbohydrates before their training sessions. Not good, because we want to conserve as much muscle tissue as possible. Anyway, we must fuel the body before cardio. Some good examples are carbohydrate protein shakes, fruits, and at the very least, branch chain amino acids.
If you want to maximize fat loss over a period of time, stick to fed, high intensity interval cardio sessions. If cardio fits into your schedule best in the morning, then do it. Just make sure you fuel up with a fast digesting carbohydrate beforehand. If cardio works better for your schedule in the afternoon, great. You will burn fat either way. There are no significant studies that say fasted cardio can significantly increase body fat loss. All we do know is that there is a chance that our bodies can use muscle tissue as fuel after a certain amount of time. So what's the tangible takeaway? Do what works for you. Track your body fat and your lean body mass over time and see where your plan takes you. If you do choose to do cardio immediately after waking, I do suggest getting some fast fuel in your system such as a fruit, carbohydrate protein shake, or branch chain amino acids.
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Thanks for reading!
Blomstrand, Eva, and Bengt Saltin. “Effect of Muscle Glycogen on Glucose, Lactate and Amino Acid Metabolism During Exercise and Recovery in Human Subjects.” The Journal of Physiology 514.1 (1999): 293–302. Web.