Is AM Fasted Cardio for You?

18 Mar

early-morning-workout-tips-300x200[1]I’m a fan of morning workouts.  I think they’re the best, and there’s a lot of scientific research to support the benefits of morning exercise.  AM training sets the tone for your entire day — physiologically, psychologically, and emotionally.  Exercising in the morning just feels good.

And, for our athletes whose goals include strength, speed, and power development, I recommend never training on an empty stomach (as is supported by the scientific literature).

But what if your exercise goals involve weight/fat loss?

There is a debate among exercise science cognoscenti as to whether or not to consume carbohydrates prior to fat-burning exercise.  In other words, should you do morning training on a fasted (empty) stomach or after breakfast?

During cardiovascular exercise, a significant portion of your energy production comes from burning fat. When your diet is higher in protein and fat, your muscle adapts by more effectively utilizing fat and sparing muscle glycogen (the stored form of glucose). Additionally, cardiovascular exercise improves your muscle’s ability to use fat for energy while sparing breakdown of muscle protein. The percentage of carbs used during cardiovascular exercise increases when your diet is high in carbs.

After a night of sleep, fat is available for energy because liver glycogen stores are somewhat depleted by the overnight fast. This means there is less available glucose to burn as fuel and your muscle goes to other sources of fuel — fat or muscle. During cardiovascular exercise, fat is released from stores, resulting in more fat to be available for working muscles. If a carb-rich meal is consumed prior to the workout, glucose becomes the preferred energy source and fat-moving enzymes are shut down by the rise in the hormone insulin, which facilitates conversion of absorbed glucose into stored fat and glycogen.

It is reasonable to infer that eating glucose (carbohydrates) prior to exercise intended to burn fat (i.e., cardiovascular exercise) is counterproductive. Research supports that fat burning is greater in a fasted state vs. a fed state and that fasted cardio improves the contribution of intramuscular fats used in energy production during cardiovascular training.

In other words, research supports that fat burning is greater in the fasted state than in the fed state.

Fasted training improves the muscle’s ability to burn fat more than similar exercise done with prior carb intake. Perhaps more crucial for the low-carb dieter, fasted-state cardio prevents the drop in blood glucose seen in exercise after a carb meal. This avoids the crash that can occur when training after eating sugars or carbs.

Please keep in mind that fasted cardio is just that: It only applies to cardiovascular exercise and not to high-intensity strength and power training.  Athletes who are training to improve performance should always eat prior to a workout, and never train on an empty stomach.

If you’re an athlete who wants to get stronger, faster, and more powerful, make sure you eat appropriately prior to training.

However, if your goal is to burn fat, give fasted morning cardio a try.

Get STRONGER, Get FASTER!

Your thoughts?

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