Is It Better To Exercise On An Empty Stomach?

The issue of whether or not one should hit the gym before or after breakfast has been hotly debated for some time. Recently – thanks to the rise of intermittent fasting – the theory has surfaced that exercising on an empty stomach could help you burn more fat for fuel.

Does this hold up under scientific scrutiny, though? Are there any other factors to consider when deciding whether or not to exercise while fasting?

Running On Fat

In an effort to answer this question and settle the long-standing debate, a study published in the American Journal of Physiology — Endocrinology and Metabolism put 10 overweight men through two different workouts. First, the participants jogged for 60 minutes on an empty stomach. Then, on another occasion, the same men performed an identical workout two hours after eating a high-calorie, high-carb meal.

Throughout the study, the researchers took samples of both blood and adipose (fat) tissue from the participants.

And, what did the researchers uncover through all of their poking and prodding? When the men fasted before their exercise, the expression of two genes – PDK4 and HSL – increased significantly. The activity of these genes decreased when the men ate before their workouts, though.

Now, the big question: So what?

The research team got all excited upon seeing these genes fire up, but, to most people, this means nothing. Well, as it turns out, both of these genes are very closely connected with the breakdown of adipose tissue. Their increased activity, then, suggests that the fasted workout burned more fat for fuel than its fed counterpart.

Things To Think About

So, based on these findings, it seems pretty clear that exercising on an empty stomach does indeed burn more fat than exercising after having eaten.

Before you rearrange your entire meal and workout schedule, though, there are a few things you need to think about.

First of all, is this realistic for you? Keep in mind, for this trick to work, you would have to exercise before breakfast. For most working adults, that would require hitting the gym around 5 or 6 in the morning. Is that really practical and possible for your situation?

Consider, as well, how fasting impacts your general energy levels. For some people, trying to work on an empty stomach is very much like running a car on empty. You probably won’t get very far. Others do just fine, though. Still, many people find that they are able to adapt to the whole fasted workout thing even if it seems impossible at first.

Finally, think about your goals. If you’re looking to build impressive strength or hulking muscles, fasted workouts probably aren’t the best idea. Not only will your workout performance suffer slightly but your muscles will likely struggle to recover properly unless your diet is absolutely on point.