Fasted Cardio: Why it Works

If you’re a fitness junkie, chances are you’ve heard the term fasted cardio. Fasted cardio is the act of competing your cardiovascular exercise in the morning and on an empty stomach.

Can early morning fasted cardio help you lose fat faster than other cardio methods?

The answer is yes.



The basic idea behind cardio on an empty stomach is that your body will be more likely to use its own fat stores as fuel instead of the food you just ate. This idea is simplified and a little misleading. Fasted cardio will help you burn more fat during your workouts, but the reason for why it works is a bit more complex.



First thing in the morning, after you’ve been fasting all night, your body’s natural hormones have the perfect profile to burn fat. After a good night’s rest, you have all of the following working for you:

  • Low Insulin Levels: After not eating for the last 8+ hours, our insulin levels are very low. This is good because fat cannot be mobilized in the presence of high insulin levels. With low insulin levels, your body is better able to release and transport fat to be oxidized.
  • Low Blood Sugar: Some people might think this is a bad thing, and it can be – if it ends up impairing your workout performance. However, if it doesn’t, low blood sugar forces your body to draw on fat reserves because there is not enough glucose to power your workout.
  • Higher Growth Hormone Levels: Your growth hormone (GH) levels will be higher while you are sleeping. All throughout the night your body is pulsing out GH. Come morning time, your levels will be lower, but they will be higher than at other times during the day. Growth hormone and insulin are antagonists. When one is high, the other is low. Since your insulin levels are low upon waking, your GH levels are higher. Growth hormone is highly catabolic to fat cells – ie it breaks down fat stores.



Fasted cardio is beneficial to fat loss because of the state your metabolic environment is in. Those low blood sugar levels and low liver glycogen stores, resulting from a night without eating, forces your body to learn how to metabolize fat more efficiently. While anaerobic exercise uses glycogen/glucose for fuel, the point at which your body stops using fat and starts using glucose can be manipulated. Training on an empty stomach first thing in the morning is one of those ways.


(I do not suggest fasted cardio if your workouts are already suffering due to lack of energy, if you are not a morning person, or if you feel faint while working out an empty stomach.)


Try it out and post your comments below!





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