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Protein Misconceptions

by Louise April 11th, 2011 | Diet, Exercise, Nutrition
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The biggest misconception: The more you workout and lift weights, the more protein you need.

Proteins should account for 10-18% of total calories in one’s diet. One with a sedentary lifestyle needs about .8 grams per kilogram of body weight. Those working on strength need a bit more (1.2-1.6 g/kg), while endurance athletes need the most (1.2-1.78 g/kg). Thus, a 175-lb. sedentary male needs about 250 calories from protein, while a long distance runner weighing 160 lbs. would need about 500 calories from protein. However, these amounts do not linearly increase based on increased duration of a run, or an increased number of repetitions while weight training. Why?

The answer to this is related to another common misconception: Protein is necessary for muscular energy.

I see many people trying to load up on proteins before workouts, hoping it will increase their performance. Your body has a preferred fuel source depending on exercise activity intensity. For extremely high intensity activities (anything taking just a few seconds to a few minutes, such as a sprint) or high intensity activities (a bike ride, swim, or run less than 20 minutes), your body turns to its glycogen stores, which come from carbohydrates. One hour of high intensity exercise can deplete over 50% of the glycogen stored in your liver. After 2 ½ hours without replenishment, the stores in your muscles and liver will be empty, resulting in decreased performance. Glycogen is much more efficient than fat, but your body will use fat if the exercise intensity is only moderate (i.e. hiking). Only when your body has no fat or glycogen will it turn to protein for fuel, by breaking down muscles, which you can imagine, is less than ideal.

So what does protein do? Proteins are essential for tissue repair (which typically results in increased muscle size after strength training) and antibody synthesis; it also has a role in cell structure and function.

One of the important things to learn from this is that eating a food high in protein (such as a protein bar) before a workout doesn’t do your body much good during the workout. Your body won’t be needing protein until after the workout, when is begins to repair the micro-tears that have been created. The ideal food before a workout is high in carbohydrates, moderate in fiber and salt, and low in fat and protein.

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All health and medical information is provided for educational purposes and is not meant to replace the medical advice or treatment of your healthcare professional.