Pre-Workout Feeding Myth – You Need Food for Energy Beforehand

Continuing along with our discussions on feeding and working out, I once again came across another good article by Ori about eating before a workout (or not):

Diet Fallacy #2. EATING BEFORE EXERCISING will provide your muscles with instant energy

Many people assume that the human body operates like a machine and therefore in order to work, it needs to be fueled liked a machine. Eating before exercise seems to make sense. But does it really?

As you’ll soon realize, the idea that pre-exercise meals provide the muscle with instant energy is literally wrong, often misleading and counter effective.

In order to provide the muscle with nutrients and energy, food must be first fully digested. During digestion food is broken down into smaller compounds, yielding molecules of amino acids, fatty acids and glucose ‘ which are transferred to the body’s tissues through the circulatory system. The digestion elimination process, that occurs in the stomach, intestines, liver and kidneys, respectively, requires substantial amounts of energy. During digestion, blood flow shifts from the brain and muscles to the inside organs (responsible for digestion and elimination). That shift in the blood flow profoundly affects the brain and muscle tissues, lowing their capacity to perform and resist fatigue.

The question remains: “What about meals that require almost no digestion?” such as those made from fast assimilating nutrients. (Note that fat is a slow digested and assimilated nutrient compared to protein and carbs.)

Consuming a pre-exercise meal made from a blend of fast releasing proteins and carbs (such as whey and sugar), looks initially quite appealing. In theory such meals would nourish the muscle tissues with amino acids and glucose to inhibit muscle breakdown, while providing instant energy. It all makes sense, but even so, in real life, things often work differently than in theory.

Recent studies demonstrated that eating fast releasing foods before or during exercise could be counter effective, to say the least. Investigators in the school of sport and exercise science, University of Birmingham, Edgbastion, England found that ingestion of carbs before exercise adversely elevated plasma cortisol levels. Interestingly enough, there was a significant reduction in post exercise cortisol when carbs were not ingested before exercise. Furthermore, there was a faster shift from carb to fat fueling during exercise, when a pre-exercise meal was not applied.

As for protein, what failed to reach mainstream nutrition knowledge is the already established fact that protein rich foods raise cortisol levels if applied incorrectly. Studies at the University of Lubeck, in Germany, found that oral administration of fast releasing protein foods such as hydrolyzed (pre-digested) proteins, have an even more profound cortisol elevating effect, compared to whole protein foods.

Note that chronic elevated cortisol has been associated with muscle wasting and fat gain (in particular abdominal fat.)

In summary, pre-exercise meals may rob the brain and muscle of energy (due to digestion). Eliminating the digestion effect of pre-exercise meals may only make things worse. Eating meals made from fast releasing proteins and cabs, before exercise, can cause a profound cortisol elevating effect during and after exercise. This may severely compromise ones ability to build muscle and burn fat.

Take home points

Obviously working out in the AM fasted works for this. If your workout is later in the day and during your eating hours then don’t worry. Just make sure your last meal was a couple hours before your workout. Remember that our goals are to use up muscle glycogen (so we can replace it along with amino acids to rebuild) and also to burn fat in the period after the workout (if you are waiting to eat 60min pwo). None of this can be accomplished if we are loading our bodies with sugar and carbs before the workout even begins. As you will see in mainstream media, this is not the message you are getting. Look everywhere and you will see Gatorade, Energy Drinks loaded with sugar, Workout Drinks/Bars…..people saying we need energy to workout, when in fact we have plenty….it’s called fat stores!
photo by kenmccown

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