Eating large amounts of carbohydrates before a race or athletic competition is commonly referred to as carbohydrate, or carb, loading. Although it may be beneficial, it must be done correctly to improve athletic performance. If carb loading causes weight gain, abdominal cramping or irregular blood sugar levels, consult a dietitian or doctor before continuing.
About Carbohydrates
Carbohydrates are one of the body's primary energy sources. They are commonly divided into complex carbohydrates and simple carbohydrates. Complex carbs take a long time for the body to process, due to their composition, whereas simple carbs are quickly digested and assimilated for energy use. When you consume carbohydrates, your body turns them into sugar and stores any unnecessary carbs in the form of glycogen. Glycogen is stored in the muscles, and you use it when you exercise.
Carb Loading
Normally, your muscles store enough glycogen to support about 90 minutes of exercise. If you exercise beyond this point, the muscles may become tired, resulting in muscle fatigue. Therefore, endurance athletes often attempt to increase glycogen stores by stocking up before an athletic event. In an article featured in "Fitness" Magazine online, Nancy Clark, author of "Nancy Clark's Food Guide for Marathoners," suggests eating 3 to 5 g of carbohydrates for each pound of your body weight per day for two to three days before a marathon, instead of only loading up the day before.
Studies
Carbohydrate loading may not be equally beneficial for all athletes. According to a 2006 study by researchers at Baylor University, gender plays an important role in the overall effectiveness of a carb-loading diet. The female body releases a hormone known as estradiol, which plays an important role in the development of secondary sex characteristics. This hormone interacts with glycogen storage. Therefore, women may need to increase their calorie and carbohydrate intake even more than men during a carb-loading diet. Researchers continue to study the exact physiological differences between male and female carb-loading programs.
Considerations
Athletes with blood sugar conditions such as diabetes should consult their doctors before attempting a carbohydrate-loading diet. Keep in mind that carb loading is a gradual process -- many athletes start to slowly increase their carbohydrate intake as much as one week before a competition. Your fitness level and exercise intensity level may also influence the effectiveness of carbohydrate loading. When it first became popular in the 1960s, a carb-loading diet involved a three- to four-day depletion phase, in which athletes trained hard and ate a low-carb diet. This initial depletion stage is now considered unnecessary by most athletes.
References
- MayoClinic.com; Carbohydrate-loading Diet; Nov. 19, 2010
- "Fitness" Magazine: The Truth About Carbo Loading
- American Council on Exercise; Carb Up for Race Day; Marion Webb; March 31, 2010
- "Journal of the International Society of Sports Nutrition"; Gender Differences in Carbohydrate Metabolism and Carbohydrate Loading; Jennifer Wismann and Darryl Willoughby; 2006
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