I’m often asked my opinion on various diets and training methods at work, one of the most common is fasted cardio. Fasted cardio just means cardiovascular exercise (like running) performed in a fasted state (for a lot of people this means in the morning before breakfast).
Here’s the thing, if weight loss is your goal, whether you’re doing your cardio before breakfast or after breakfast, it’s not going to make a difference to your overall weight loss.
There’s been a lot of research on this where they’ve taken groups of people who have done their cardio either before or after breakfast… but found that as long as the calorie intake and energy output was the same in each group throughout the day, net results on weight loss was the same in each group.
The reason for this is that our bodies are good at using the fuel that they have available. So if you ate a heavy breakfast and then did some exercise then you’ll have all of that fuel to use during your session instead of using your body’s fat. However when you then go about the rest of your day, you’re not going to be using as much of that breakfast fuel as you burnt it up during your workout, you’re going to be using your body’s fat for fuel instead.
So in summary, at the end of the day the energy all evens out. So the weight loss will still be determined by the total amount of energy you’ve taken in vs energy output across the day.
This doesn’t mean that fasted cardio doesn’t have it’s place. Lots of people enjoy fasted cardio because it suits them – not everybody has the time or the stomach for a breakfast before hitting the gym at 6:00am. But don’t get hung up on the idea that fasted cardio is going to work some magic and you HAVE to drag yourself out of bed at 5:00am to get it… the extra couple of hours sleep may actually be more beneficial for your health.