Fitness / Strength Training

Should I Really Do Fasted Cardio?

Our expert gives us the rundown.

Fasted cardio is a hot topic in the fitness community. Some people think it’s great for fat-burning and speeding up your metabolism and others say it’s a no-go. There are a lot of opinions out there so we spoke to Kelly Chase, an Aaptiv trainer and certified holistic health coach, to give us the answers once and for all.

A ‘Fasted State’ Defined

A fasted state means your body has completed digestion and absorbed all the nutrients from your last meal or snack. When people refer to fasted cardio, Chase explains, “This means training after not having eaten anything for several hours (four to six hours). Sometimes this can mean you haven’t eaten breakfast yet so your last meal was dinner the night before.”

Does fasted cardio speed up fat loss?

There is a belief that fasted cardio means you’ll burn fat quicker. According to Chase, while there is some truth to this, it isn’t as straightforward as it seems. “When we train fasted, our bodies are turning to other energy sources, like fat, after our glycogen stores are depleted and our insulin is low after not having food for eight to 12 hours,” she says. “So, yes, then you’re burning fat.”

But it’s important to look at how the body burns fat not only during a workout but also after it. In fact, according to Chase, eating prior to a workout means your body will burn more fat for longer throughout the day, especially if you fill up on carbohydrates.

If you want to burn fat, starting a regular exercise routine is a great way to do it—and Aaptiv can help. 

Will fasted cardio affect my energy levels?

A common concern about fasted cardio is that energy levels will fall. Chase does agree that this can happen. For those who work out in the morning like Chase does, your cortisol level tends to be higher. “This spike in cortisol provides you with the energy needed to do fasted training,” she says. If you’re not used to fasted cardio, your energy level can plummet at first. Until your body adapts, you may struggle with your usual training.

Will fasted cardio cause muscle catabolism?

Muscle catabolism means the breaking down of muscle tissue,” Chase says. There are concerns that fasted cardio will cause this to happen faster. But there is good news for those who enjoy fasted cardio and don’t want to sacrifice muscle growth or size. If you’re still meeting your macronutrient goals throughout the day, you can still build muscle mass success. “Training fasted can cause muscle catabolism if you’re not eating enough of the right foods … to sustain [it],” Chase cautions.

Looking to build muscle mass? Check out the strength workouts on Aaptiv

What if I don’t want to train fasted? What if I do?

“I think every individual is different and should experiment with what type of training works best … whether that’s ‘fasted’ or ‘fed’ training,” Chase says. If you prefer to train fasted, then do it. If you want to eat before a workout, then eat!”

Here are some of Chase’s favorite pre-workout snacks and meals:

If you’re a morning person, you’ll probably prefer a light snack. Chase recommends a half cup of oatmeal or a banana. She aims for “something quick and easily digestible.” Prefer to train later in the day or at night? Chase likes to eat 60-90 minutes before her workout. Have a quarter to a half cup of sweet potatoes with the protein of your choice. Cooked oatmeal is still a great option as well. She also adds a cup of dark leafy greens to each meal: “I believe vegetables should be consumed at almost every meal to really fuel our bodies with proper nutrients.”

Fitness Strength Training


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