I often get the question of whether it’s better to eat or not eat before a morning workout.  Over the years, this topic has brought about a lot of confusion.  Many have heard of a popular fat loss strategy which involves performing cardio first thing in the morning on an empty stomach.  But does this truly work?  And at what cost?  I did a little research to help guide you on what may be the right thing for you.  I’ll try to keep it simple so you can understand how the body works and how it uses food so you can recognize what might be the best approach to fat loss.

Fasted cardio has been a technique that has been suggested by many fitness enthusiasts over the years as a superior method to burn fat.  The idea is that by performing cardio in the fasted state before you eat in the morning, the calories you burn will be a greater percentage from fat, and lead to superior overall fat loss.  An overnight fast brings about a reduction in circulating blood sugar levels, reducing the amount of carbohydrate being stored in the body.  With carbohydrate levels diminished, your body is forced to rely more on the use of fat rather than carbs to fuel your workout.  Seems like an ideal way to rev up fat loss, right?  Unfortunately logic doesn’t necessarily translate into practice.  There are several major issues with this strategy. I’ve listed a few reasons why below.

Problem 1:  Level of Intensity

Research does show that fasted cardio can promote greater fat use compared to exercising in the fed state.  During moderate to high intensity aerobic exercise, the body breaks down more fat when you’re carb depleted. The rate of breakdown exceeds your body’s ability to use the extra fatty acids for fuel which then can’t be oxidized by the working muscles.  So in the end, you have trudged through a grueling cardio session low on energy reserves with nothing to show for it. 

Problem 2:  EPOC

Another problem with fasted cardio is that it blunts excess post exercise oxygen consumption (EPOC), or the number of calories expended after training.  Eating, however, before exercise has been shown to increase the magnitude of EPOC, with the majority of calories coming from fat stores. 

Problem 3:  The Energy Factor

Studies show that High Intensity Interval Training (HIIT) is better for fat loss than steady state cardio.  But have you ever tried to do a HIIT workout without eating for more than 10 hours?  If so, you likely hit the wall pretty quickly.  To perform well, your body needs a ready source of carbs or it can’t sustain an elevated training intensity.  The outcome is fewer calories burned both during and after exercise, blunting fat loss.

Problem 4:  Muscle Loss

One issue of fasting is that it can cause muscle break down.  By being low on carbs, your body uses muscle tissue to be used for energy during exercise.  So all that hard earned muscle you have worked to build is being burnt away!  Remember, the more muscle you have, the higher your metabolism.  To stop this process, it’s important to eat right away after you wake up to put an end to the fasting process your body went through while you slept.

Problem 5:  The Big Picture

Your body continually adjusts its use of fat and carbs for fuel depending on a variety of factors.  As a general rule, if you burn more carbs during a workout, you’ll ultimately burn more fat in the post workout period and vice versa.  So who cares if you burn a few extra fat calories in the course of a workout if an hour later the ratio shifts?  The only thing that matters is total fat loss.  This should be viewed as a process during the course of a few days or weeks, not on an hour to hour basis. 

All in all, there is little reason to perform cardio on an empty stomach if your goal is fat loss.  At best, the effects on body composition won’t be any better than had you trained in a fed state.  At worst, you’ll lose muscle and perhaps even reduce total fat loss.  Consuming a proper pre workout meal can help increase your strength, improve recovery, as well as boost the amount of calories you burn at rest for up to a day after training. 

So now that I’ve suggested eating prior to working out, what kinds of foods are best?  A good rule to follow is to eat a combination of carbohydrates and protein an hour or so prior to exercise.  Examples of this would be a shake made with a natural fruit juice and whey protein, or some eggs and a piece of fruit.  People who have consumed a protein shake before and after resistance exercise experienced greater gains in lean body mass and increased 1 rep max strength over those who did not.  It would be wise to experiment to see what kinds of foods work well with you and your digestive system.  Not everyone enjoys eating prior to working out… BUT, there are too many benefits to not get that pre-wod meal in.