Should you add a fasted cardio workout?

Is it more effective to do a fasted cardio workout to burn more fat? Whether or not you should eat first thing in the morning before working out is a highly debated topic.

Some people believe that empty stomach cardio fastens their fat loss results whereas others say that it can hinder performance.

What is fasted cardio?

At the most basic level, fasted cardio is cardiovascular exercise without having eaten.

A fasted state is one in which you have completely digested and absorbed your last meal and your insulin levels are at a low or baseline level.

Most of the time a fasted workout occurs in the morning after not eating for the past six to 10 hours prior. 

The theory behind fasted cardio is to work at a level that’s less intense so that when glucose isn’t readily available, the body starts to break down stored fat for energy instead.

Fuel for your body

When you exercise, your body’s first fuel source is carbohydrates — after you eat carbs, your body has glucose (the building blocks of carbs) available in your bloodstream and muscles for energy. Long, intense cardio sessions burn through the available glucose and then start to burn stored energy.

What kind of cardio should you do?

Low to moderate intensity cardio such as incline walking, light cycling, stairmaster or a slow run are good options. You will find that steady-state cardio is one type of exercise that can help you burn fat.

Although steady-state cardio is a good choice to help you reach your weight loss goals, your body will only burn the fat during your workout and then go into regular operation mode for the rest of the day.

However, if you want a routine that will keep working for you all day, incorporate interval training or a high-intensity workout into your routine. Depending on the type of training you choose, this can mean adding in squats, lunges and jumping into your workout.

Exercises should be at a moderate or an intermediate level workout intensity. Do each exercise for 35-40 seconds with a 20-second rest period in between.

You also can adjust the intensity or speed of each exercise to increase the potential benefits by changing any workout into a treadmill HIIT workout. 

Benefits of fasted cardio workout

Are the benefits of fasted cardio worth rolling out of bed and knocking out your workout?

May increase fat burning

Fasted cardio has shown to increase the relative percentage of fat oxidation, meaning that more of the calories you burn during the workout comes from stored body fat.

Burn stored energy

The type and intensity of exercise has an impact on the way that your body chooses to fuel your workouts. The ideal conditions for fat burning includes not recently ingesting glucose and not working at a high intensity to break down muscle tissue.

Time saver

You can save time because you are basically waking up and going right to cardio. You don’t have to worry about fitting it into your day later on. Knocking it first thing in the morning can help get your day started and boost your mood for the rest of the day.

Leaving your cardio to the end of the day makes it easier to skip it.

Downsides to fasted cardio

Burn muscle not fat

Exercising on an empty stomach may hinder muscle-building. While practicing fasted cardio, your body may start a process known as gluconeogenesis which converts protein into fuel, meaning it is harder to use that protein to build muscle instead.

Impact type of workout

High-intensity workouts such as HIIT, CrossFit or boot camps will likely become considerably more challenging on an empty stomach than in a fed state. Such workouts require carbohydrates for fuel and energy, without them you could feel nauseous, weak, or tired.

You may not see any changes

You could be getting up early and doing a fasted morning workout a couple of times a week and not notice any changes. There’s no guarantee that it will work for you and if so, how your body reacts is as unique as you are.

Does it really work?

It depends. While some research studies support the idea that more fat is burned without carbohydrates in our system, it might be difficult to have enough energy for any cardio session.

However, in another study, there was very little difference between participants who performed fasted and fed cardio in their overall body composition.

What to eat after fasted cardio

It depends on the intensity and length of your training as well if you’ll be working out later in the day.

• If you performed a low to moderate intensity session in under an hour, have a meal containing an adequate amount of protein, at least 20 grams. Carbs are optional since you haven’t done much to deplete your glycogen stores. However, carbs are beneficial if you’ll be lifting weights later in the day.
• If you performed a HIIT cardio workout, you’ll want to eat protein and pair it with some fast-digesting carbs. This is especially important if you’ll be weight training later in the day.