The Five W’s of Carbohydrate Loading

By Amanda Turner MS, RD, CSSD - April 13, 2017

Carb-loading- sounds dangerous right? Fear not, because outlined below are the reasons why carb-loading can be beneficial for certain athlete groups to promote maximum performance and energy levels.

WHO benefits the most from carb-loading?
Endurance athletes exercising at high-intensity for 90-120 minutes or longer without breaks (i.e. marathon runners, cyclists, triathletes, etc.). Carbohydrate loading is not appropriate for activity less than 90 minutes in duration, or activity that has frequent breaks (i.e. team sports).

WHY is it important?
Carbohydrates are the primary fuel source during physical activity. As activity intensity and duration increases, glycogen stores decrease in the muscle and liver. Without introducing more carbohydrates during activity there will inevitability be a time when there are no longer any stores of energy left in the body, at this point athletes have "hit the wall" or "bonked." Carb-loading before a big event may help to slow this process down and maximize the amount of glycogen available in our muscles.

WHERE do the extra carbohydrates go?
Dietary carbohydrates are converted into and stored as glycogen in the muscles and liver. To maximize glycogen storage,traditional carbohydrate loading first depletes current glycogen stores during the first 3 days of the week leading up to the race by decreasing carb intake and maintaining exercise intensity. Then,the percentage of carbohydrates is increased significantly days 4-7 so the muscles and liver can store up to 1800-2000 calories worth of glycogen energy for the body to utilize during long periods of moderate-intense exercise.

WHAT am I supposed to eat and how much?
In the week before your event, the first three days of the depletion phase will consist of 30-40% carbohydrates. During the glycogen restoration phase, simple carbs will be the easiest for you to digest and will compromise between 70-85% of your diet in the days leading up to your event. Increasing the amount of food choices from carbohydrate sources including tortillas, white rice, white potatoes, white bread, white pasta, and low fiber fruits such asbananas will help to promote glycogen storage. It is important to continue to eat within your normal calorie range and limit overeating which can hinder performance. It can be helpful to practice eating the foods you plan to eat during carb-loading, during your training and avoid introducing new foods into your diet in the days leading up to your race and on race day to help limit gastrointestinal upset. Because the diet increases in carbohydrate significantly while activity decreases the final four days before your event, athletes will commonly experience some uncomfortable side effects: bloating, gas, and muscle soreness and stiffness.

WHEN is it best to carb-load?
Carb-loading is most effective for use in your “A” race, one to two times per year. Choose your most important race or event, preferably your longest one and make a plan early during training for what foods you will want on your carb-loading week to test how your stomach reacts to them and maximize race-day performance.

To Carb-Load or Not?
Carbohydrate loading can be a good strategy for individuals who do not suffer from endurance-related GI distress and are interested in maximizing muscle glycogen stores for their event. Research does suggest that eating a balanced, high-carbohydrate (~60-65%
carbohydrate) daily can have as much of a beneficial effect as carbohydrate loading, without the uncomfortable side effects. When an athlete is deciding whether or not to carbload, it is important to consider race length, intensity, GI tolerance to food, and food availability before making a decision. Remember, carbohydrate loading is a week long process of depleting and restoring carbohydrate stores. It is NOT having a heavy pasta meal the night before an event. It is NOT having a huge baked potato with butter, sour cream, cheese and bacon (these toppings are very high in fat). It’s common for athletes to mistake carbohydrate loading with overeating and the feeling of overfull in the days leading up to their event. It is recommended for athletes to listen to their bodies and finish their meals comfortably satisfied. When there is a lot of food going into the body, there will be a lot to come out of it at some point . . . . . And no one wants that to happen on race day!