Understanding Proteins and Carbohydrates to Optimize Performance

Because of recent diet fads, marketing campaigns, and general misinformation, athletes have been led to believe that protein is the essential nutrient for an athlete. While proteins are a critical component of body tissues, they are not the best source of energy to fuel an athlete’s body.  Because of the myths about proteins circulating amongst athletes, athletes tend to consume way more protein than their body’s actually need.

On the other hand, carbohydrates in general have incurred a bad reputation over the past decade. Popular fad diets that are high protein and low carbohydrate have been marketed as a healthy means to lose weight. However, this type of diet is counterproductive for athletes.

For athletes, carbohydrates need to be the highest nutrient source and should make up the greatest percent of the athlete’s total dietary intake in a day.

How many carbohydrates should an athlete consume in a day?

The amount of carbohydrates recommended for athletes is between 55% and 65% of their total dietary intake. This has been more specifically calculated for athletes depending on the level of intensity of their sport.

Daily recovery from a moderate to heavy endurance exercise program is recommended to be 7 – 12 grams of carbohydrate per kilogram of body mass per day. This would mean consuming somewhere between 1,960 and 3,360 kilocalories of carbohydrates for a 155 lb athlete throughout the day to meet his/her energy needs.

An athlete engaging in an extreme exercise program (4+ hours per day) is recommended to consume 10 – 12 grams of carbohydrate per kilogram of body mass per day. If the athlete is not able to maintain his/her weight, more carbohydrates would need to be consumed to match the athlete’s caloric expenditure.

Choosing Nutrients Wisely

Once an athlete understands that the primary fuel source for his/her muscles is actually carbohydrates and not protein, an athlete can then make the appropriate changes in his/her food intake to provide the fuel necessary to keep his/her body performing at the highest levels. If an athlete does not consume enough carbohydrates in his/her diet, the athlete’s body can run out of stored glycogen and blood glucose. This will cause the athlete to fatigue both mentally and physically.

Athletes also need to know that once glycogen stores are depleted, the body will breakdown protein sources to provide fuel for the muscles – this includes muscle tissue. So if an athlete does not consume enough carbohydrates, the athlete’s body may actually begin to breakdown muscle tissue as a source of fuel. This is counterproductive for any athlete.

Knowing how to properly fuel the body is important for every athlete. While all of the essential nutrients are important for the health of the body, carbohydrates are the essential fuel for the athlete.


Benardot, D. (2006). Advanced Sports Nutrition: Fine-Tune your food and fluid intake for optimal training and performance. Human Kinetics: Champaign, IL.

Burke, L & Coyle, E. (2004). Nutrition for athletes. Journal of Sports Sciences 22(1): 39-55.

Diabetesnet.com “Glycemic Index”, (Accessed on January 13, 2011).

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