To Break or Not to Breakfast | Should You Be Doing Fasted Cardio?

To break or not to breakfast? That is the question! For those of you not familiar, I’m talking about breakfast or fasted cardio. On the one hand, we have everyone’s favorite meal, hearty and prepping you for anything the day can throw at you. On the other hand, is fasted cardio, a debatable theory that states that you burn more fat if you work out before eating. Personally, I can’t work out with food in my stomach without hurling (pleasant picture, I know), so fasted cardio is the only way for me to go. Either way, I figured it would be best to research the matter just to make sure I wasn’t doing anything detrimental in the long term. While I can’t make a decision for all readers, I can provide you all with the facts that I have found.

Running in the country

What Is Fasted Cardio?

To put it simply, fasted cardio working out first thing in the morning before you’ve eaten. Since we’re talking facts here, the scientific definition is exercising at an optimum time for your body to burn fat because your insulin levels are low, causing your body to look towards fat stores for energy. Makes sense so far right? Now I know what it is. But what I really want to know is, does it work? On paper, it makes sense. But, as we all know, very few things in life are ever that simple. Fasted cardio is a highly researched and debated topic in the fitness and scientific world, and no conclusive decisions have been made. An important thing to note is the amount of calories you burn won’t change based on whether you’re in a fasted state or fed state; it’s where the calories are coming from that’s different. So far, these are all things that researchers can agree on.

So if that’s what researchers agree on, what don’t they agree on?

This is where it gets tricky, and you’re going to have to use your awesome internet detective skills to determine what’s best for you. I’ve done some research and boiled down the facts to non-scientific English, but this is just my interpretation, and it’s always best to do your own research.

Arguments In Favor Of Fasted Cardio

  • Carb intake reduces fat oxidation (this is just one study, but there are several others that support this claim). Therefore, you burn more fat on fasted cardio. True or not, I’m going to need all the opportunities I can get to burn fat.
  • If your body relies on food for energy and you don’t have any food in your stomach, your body will tap into stored energy (read: fat cells) to get you through your exercise (this is an inference I reached through common knowledge, no source, but I also couldn’t find anything refuting it, so it must be right…right?).
  • Fasted cardio can potentially increase the amount of carbohydrates your body can store. No, this doesn’t mean you can now eat all the pasta you want and not be affected. This allows you to increase your endurance for a big day (endurance runners, cyclists, etc.), in other words, carb-loading will mean more than just eating fettucini alfredo before your run, a la Michael Scott.
  • If you have a stubborn area of fat that won’t seem to go away (Hello, food baby. Am I right, ladies?!), fasted cardio could increase blood flow to those areas and could help out with that.

Healthy avocado, egg open sandwiches on a plate with colorful tomatoes against a rustic wood background

Arguments Against Fasted Cardio

But seriously, imagine how hungry you are in the morning. Now imagine how hungry you are after a workout. Now put those two together and you get a hangry little monster inside your stomach, this really should be the number one reason for someone to not do fasted cardio.

[RELATED POST: Healthy Meal Prep Ideas For Breakfast | Overnight Oats]

Wait, I’m Confused. So Should I Do It Or Not?

Don’t be confused! It’s really up to you. Try fasted cardio a few times and see how it makes you feel. You could research for days (trust me, it’s not fun, especially for a non-sciencey person like myself), but no definitive decision has been made or will be in the near future. If you work out in the morning, it’ll probably be easier to test out. If you don’t, maybe you should just read the one study that says you’re not missing out on much. Either way, the best things to help you become or stay healthy are a healthy diet and consistent exercise. Have you tried fasted cardio? Sound off in the comments on your thoughts on the topic!

TL, DR: Maybe you should do fasted cardio, maybe you shouldn’t. Maybe it’ll help you with your stubborn fat; maybe it will break down your muscle. Po-tay-toe, potah-toe. You can never go wrong with eating properly and exercising.

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Alyssa Carlos
Alyssa is a full-time defense consultant, part-time Soulcycle addict, and imaginary jeopardy champion. When she's not getting her spin class fix, she's finding new ways to workout so she can eat more, holding concerts in her car during traffic, and aspiring to be the next Anthony Bourdain. You can follow her food adventures at or on the following social media sites

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