This week I’m going to talk about one of the ‘holy cows’ in the fitness/ personal training world, fasted cardio.
For decades, thousands of athletes have dragged themselves to the gym at the crack of dawn without daring to eat or drink anything of any substance. They perform cardio on an empty stomach as they believe that they are tapping into their fat stores. It sounds great, but does it actually work?
Let’s go to the videotape. Cardio on an empty stomach does burn more fat as a percentage, than cardio in a fueled state. So there, do we have a winner?
Not so fast, I’m afraid. This effect only holds true for untrained athletes, so that does not include you. Furthermore, fasted cardio is a highly efficient way to get frustrated and lose a ton of muscle.
As you can tell, I am rather opposed to it. It is a really outdated way of doing things and a classic case of the blind leading the blind. The underlying thinking is that in a fasted state, the body has no choice but to burn fat for energy. This is actually partly correct, but still falls short of reality.
First off, most athletes do not perform as well in a fasted state, compared to those that have eaten. As a result, the actual amount of calories burned is lower, meaning less fat is lost. Furthermore, the body tends to go into starvation mode if left without food, which leads to significantly reduced levels of testosterone, GH and thyroid hormone.
All this spells muscle loss, and makes further fat loss even more difficult as your body thinks that you are starving it, so it will then store the next meal as body fat to ensure your survival. On the flipside, in a well-nourished athlete, post workout calories will be used to refill muscle glycogen.
Lastly, your rate of EPOC (excess post-exercise oxygen consumption or ‘after burn effect’) will be substantially reduced if you train on an empty stomach. This means you’ll lose much less body fat post workout than if you had eaten.
At the very least you should do what tell my personal training clients in NYC: have about 12-15 grams of carbs and 10 grams of protein before a workout. If you are on a very strict diet, drink about 15 grams of BCAAs as they will improve performance and help spare your muscle.
To sum it up, stop the starvation cycle and start feeding your body!