Suscipio PSA #9 – Fueling Your Body

Public Service AnnouncementDisclaimer – I am not a doctor, nutritionist, or professional fitness guru. I am sharing what I’ve learned through research and experience; you all must use your own judgment in deciding what is best for you and your own health, including checking with your doctor before beginning any exercise or dietary program.


We gather at mass to fuel our souls; we study scripture, read and come together here to fuel our minds and spirits.  What are we doing to fuel our bodies?  Not just eating Real Food every day, but fueling our bodies for exercise.  

Are you supposed to eat before, during or after exercise?

 The answer is Yes.

First, the science behind it. Your body is an amazing machine, and it works constantly to maintain a certain level of glucose in your bloodstream. Glucose is fuel – it keeps your muscles moving and your brain processing. Your body changes the food you eat into glucose to power your pretty self. Once your bloodstream is saturated at the proper level, extra glucose is stored in your liver as glycogen.

When you exercise, your muscles go into overdrive, drawing glucose from your bloodstream. Once that source is used up, your liver will change the stored glycogen back to glucose and release it into your bloodstream to keep you moving. Once the liver glucose is used up, your body will start using stored fat to make more glucose for your muscles. Unfortunately, changing fat to glucose is a v-e-r-y s-l-o-w process, much slower than the rate your exercising muscles are screaming for fuel.  If you get to this point during a workout session where your muscles have used up all the free floating glucose in your bloodstream, BAM! You hit a wall! You start to shake, feel light headed and break out in a cold sweat. You just can’t keep going.

What? Isn’t the purpose of exercise to burn up fat? Why yes!  Yes it is! Just not DURING the actual exercise. Your body can’t convert fat to glucose fast enough to support exercise in the moment that you are actually moving. Fat burning takes place once you stop. Remember how your body keeps a constant level of glucose at all times? Once you’ve depleted the glucose in your body and stopped actively exercising, your body will pull from your fat reserves to balance the glucose level in your bloodstream and to recharge your liver.

You need to fuel your body for working out – give it some fast easy energy that your muscles can pull straight from your blood stream, because they NEED that fuel to function! This doesn’t mean a full meal – this means a snack, preferably one with a balance of carbohydrates (fast fuel, converts quickly to glucose and floods the muscles) and proteins (slower fuel that will hit the bloodstream about the time the carb rush gets used up). I usually have 1/2 of a peanut butter and banana sandwich before I exercise.

For really long workouts, like hiking running or marathon bike rides, you need to top off the glucose fuel tank during the exercise to avoid that muscle crash. Some folks swear by those little gel pack things; I prefer real food. I’ll carry an apple or a granola bar with me and have a bite or two every 30 minutes. Again, not a full meal or complete snack, but just enough to keep the fast fuel coursing through my bloodstream for my muscles to pull from.

It’s also important to have a snack after working out that’s a little higher in protein in order to give your body materials to repair muscles and to do its work replenishing your blood stream and liver from your fat reserves. I usually have a few slices of turkey or a piece of cheese. Some serious runner friends of mine swear by chocolate milk for after run recharging.

There are hundreds of opinions about fueling for working out, and every body is different. You each need to figure out through trial and error what works for you – what lets you get through a workout without collapsing, but still keeps your body burning fat afterward.

Fuel Your Bod.  Keep the Faith.

 Next Time: An End to Procrastination


Angela Pea lives in Texas and has been married to Mr. Pea for 27 years. She has two adult daughters, Cherry Ames, who is almost finished with nursing school, and Princess Pea, who resides in Aggieland and is studying to be an orthodontist. Her two teenage sons, The Architect and DirtBike, still live at home, where they mostly eat everything in sight and build bicycles from random parts. She is a practicing civil engineer, occasional college instructor, random knitter, beginner mountain biker,  and a secret shoe lover.  Angela blogs at Keeping the Faith.


  1. Now this I can understand. A PB and banana sandwich before and string cheese afterwards. I can do that.
    Thanks Angela, you are soooooo smart!! :o)

  2. Thank you Angela.
    That is fantastic to know.
    It makes a lot of sense.
    Emily D. recently posted..Moments of Grace & Catholic Women’s Almanac…My Profile


  1. PSA#8 – Fueling Your Body | Keeping the Faith - [...] eat as part of an exercise program. I’ve taken a whack at clearing up the confusion over at Suscipio for …

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