Understanding Carbohydrate Loading

Health Check

Understanding carbohydrate loading is important. There are controversies over the amount of carbohydrates, fat and protein an athlete should consume. Every athlete’s caloric need depends on factors like age, sex, height, and weight as well as activity level. For athletes, the recommended diet contains 10 to 15 percent protein, 30 percent fat and 55 to 60 percent carbohydrate. The recommended diet for athletes and its proportions applies equally to most of the American population.

Because of the high-energy expenditure during training and athletic competition, athletes do require more calories than the average person does. These extra calories may come from a few extra servings of fruits and vegetables as well as breads and cereals. Sugars and fats, in moderation, can serve to enhance the flavor of foods and add a few extra calories.

Carbohydrate loading is a technique frequently used by athletes. The objective of carbohydrate loading is to increase glycogen stored in muscle for use in prolonged strenuous exercise. Up to 450 grams of carbohydrate can be stored as glycogen in muscles and the liver. The practice of carbohydrate loading involves first reducing the carbohydrate content of the diet for two or three days while continuing to exercise and deplete muscles of glycogen. The diet during the first two or three days is low in carbohydrates (50-75 grams), high in fat and protein. At least 50 grams of carbohydrate serve to prevent an abnormal state known as ketosis. Ketosis is due to an undesirably high concentration of ketones in the urine and blood when carbohydrates are not available for energy. Ketosis results when the body breaks down fats which leads to a build-up of ketone bodies.

Following the two or three days of low carbohydrate intake, the diet drastically changes to a low-fat, moderate-protein and high carbohydrate (270-450 gram) diet for two or three days prior to the athletic event. During this time, the training should be light to allow muscles to store glycogen. On the day of competition, the individual may eat whatever he or she feels will help increase performance. Avoiding foods with high-fat content or concentrated sweets on the day of competition is essential. In addition, after eating a large meal, the athlete should allow four to five hours for digestion before participating in an athletic event.

After the muscles have been depleted of glycogen, it is felt that the muscle glycogen storing capacity is very exhaustive, lasting an hour or more. Carbohydrates are a major source of energy during endurance exercises. The higher glycogen stores in the muscles, the greater the potential to perform strenuous, long-duration exercises.

Understanding Carbohydrate Loading – Is It Appropriate?

Protein is an essential part of every diet. However, it is not a good food source to supply muscles with energy during athletic competition. The average part-time athlete will have enough glycogen to meet his or her energy needs from a normal diet consisting of the previously stated proportions of carbohydrates, fats and protein.

In summary, athletes have the same nutritional needs as everyone else, with the exception of additional calories to cover their high-energy expenditure. The practice of carbohydrate loading is wide spread. However, approach this practice with caution. As with any diet regime and exercise program, one should have a medical check-up and be under the supervision of a physician.

Please refer to patient education for other brief articles in our educational series. It is through these articles, in part, that we keep our patients (and others) informed of common injuries and conditions, their treatment and healthcare in general.