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Should I Work Out On An Empty Stomach?

FROM THE VAULT: Nine times out of ten, I totally recommend working out in the mornings. Of course, the next question is: “Should I work out on an empty stomach”? While working out in the morning DOES have its advantages (particularly the fact you get it out of the way so you can work your day over instead of stressing later or even missing it) is working out on an empty stomach one of them?

There’s a lot of resources out there who say yes… but what does the research say? As it turns out, there’s contrasting data and some relatively new information that might just change your mind… or not.

Fasted State Exercise Vs. Fed-State

Fasted and Fed States are the fancy-pants way of saying “working before eating” and “working out after eating”. The popular theory of the last decade or so has been that working out on an empty stomach trains your body to burn fat over readily available carbs since your body’s used up most of the previous day’s food and your stomach is on “Empty”.

Of course, not eating early morning usually happens by necessity. I mean, unless we want to wake up a half hour to an hour earlier to take in a light, pre-workout meal, most of us will probably work out on an empty stomach over taking those precious morning minutes to whip something up. I seldom eat* before I work out in the morning UNLESS my workout is going to be a couple hours after I wake up.

As far as fat loss goes however… there’s research in both camps showing fat oxidization (fat loss) on empty stomachs AND fat loss on “fed” stomachs. In short, the available information goes both ways which pretty much leaves us at “agree to disagree” depending on which side you choose. Still, most of the long-term research indicates as long as you get your proper nutrition through the day, working out on an empty stomach at the length we’re used to (45-75 minutes) isn’t going to make any more of an impact on fat loss as a whole as working out after having eaten something.

Dan’s Take

So what to do? Here it is: if you’re not an endurance athlete (of which these tests were performed on cyclists biking 2+ hours) whether you eat or not and work out for an hour or so isn’t going to make a lot of difference on fat loss. The only thing, if anything, to be concerned about is catabolism (muscle loss for you folks doing P90X/trying to build and retain muscle) and that can be taken care of with Rest and Recovery Formula after your workout. Fed-State training will certainly allow you to train LONGER but where most P90X and Insanity workouts run you around 60 minutes, I don’t need “longer”. For me, eating before my morning workout isn’t worth the extra hassle.

That said, I ALWAYS eat within 0-15 minutes after my workout.

Play It By Ear

As with most fitness answers… the question on whether to work out on an empty stomach or not lands squarely on HOW IT WORKS FOR YOU. How do you feel? Is it working? Do you have enough energy to complete your P90X workout with intensity? If the answer’s “Yes”, go for it. If you’re falling short and unable to bring intensity, maybe you SHOULD look into working out with some energy in your stomach and see how your results fare after a few weeks.

I’ve included the two studies for your reading pleasure below.

Questions? Feel free to email me here or Better yet, let’s get you the support you need to knock your fitness goals out of the park. Make me your (free) Beachbody Coach right here.

*When I work out straight out of bed in the morning without eating, I always take in at least 12-16 oz. of water before I work out and have another 16 oz. of water on hand during the workout.

Fat Loss in a “Fasted State” Research: J Appl Physiol. 2011 Jan;110(1):236-45. Epub 2010 Nov 4.
Fat Loss in a “Fed State” Research: Int J Sport Nutr Exerc Metab. 2011 Feb;21(1):48-54. 


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