When Does Enough Protein Become too Much?


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This week’s postwas written by my first dietetic intern – Christine  Scarcello. Thanks Christine!

Protein is an important nutrient for our bodies, and as an athlete it is crucial to eat the right amount of protein. Too much or too little of this nutrient can be detrimental to performance gains.

As an athlete, the majority of fuel comes from carbohydrates, which is why we’re all familiar with pasta parties and “carb loading” in the week or days leading up to a big race. Carbohydrates stored as energy are being burned during endurance exercise, while very little protein is used for fuel. However, protein is used in other ways.

During exercise, muscle synthesis (or the creation or repair of muscle) is postponed. Athletic activity works muscles and causes damage to the muscle, yet they are unable to repair or synthesize themselves until exercise has ended. Research from Montana State University has purported, for example, that running for an hour may reduce muscle protein production in the liver by 20%; other research from the Journal of Physiology report that longer duration and greater exercise intensity further suppresses the body’s ability to repair itself. The body is able to play “catch-up” after exercise has ended, which is why it is important to get a post-workout meal that contains an adequate amount of protein.

If you’re already conscious about your post-workout snack or meal, that is great. It is important to refuel those muscles once you stop exercising so that your body can start repairing and replenishing lost protein stores or muscle structure. Yet one mistake I see all too often is an excessive amount of protein intake, and – just like the famous saying – this can be “too much of a good thing.” Excess protein that isn’t used in muscle synthesis ends up with one of two fates: it is either stored – just like excess carbohydrates or fats –as body fat, or it will be excreted as ammonia in our urine. 

Research indicates that our bodies cannot use more than 2-2.5 grams of protein per kilogram of body weight (g/kg BW) in one day. (To determine your weight in kg, divide your weight in pounds by 2.2.) Many athletes or very active people only need 1.6-1.8 g/kg BW per day. Robert Wolfe, PhD, a noted clinical investigator and protein expert, says that the most effective amount of protein at any one time is 20-35 grams (or roughly 3-5 ounces of meat).

This is further supported by research that shows a significant amount of urea is produced when an excess of 40 grams of protein is consumed at once. The high production of urea indicates that the protein wasn’t being utilized in the body (for muscle repair) but broken down into ammonia and excreted. Consuming more protein than what can be used in the body can also have potential problems, such as muscle breakdown and dehydration, which will affect your performance gains.

Planning your protein intake and sticking to a few basic guidelines is an easy way to ensure you’re getting what you need for peak performance:

1. Eat several small meals per day that consist of both protein and carbohydrates. This will not only prepare you for workouts, but it will also help with muscle repair and warding off too much muscle breakdown during your training.

2. Always eat protein and carbohydrate for a post-workout meal. Your body needs both of these nutrients to initiate muscle synthesis that is necessary to replenish lost glycogen in your muscle and repair any muscle tissue damage. The standard rule of thumb is to consume one gram of protein for every 3 to 4 grams of carbohydrate in a post-workout meal.

3. Eat amounts of protein within the 20-35 gram range at a single time, and don’t exceed that amount. Instead of drinking one large protein shake containing 60 grams of protein after your workout, drink half of that amount and save the other half for another meal or snack during the day.

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