Definition
A carbohydrate-loading diet, also called a carb-loading diet, is a strategy to improve your athletic performance for endurance events by increasing the amount of fuel stored in your muscles.
Carbohydrate loading occurs when you eat a high-carbohydrate "training diet" at the same time that you scale back your activity level in the days before an event.
Purpose
Any physical activity requires carbohydrates for fuel. For most recreational activity, your body uses its existing energy stores for fuel.
But when you engage in long, intense athletic events, your body needs extra energy to keep going. The purpose of carbohydrate loading is to give you the energy you need to complete an endurance event with less fatigue, improving your athletic performance.
Carbohydrate loading may be most beneficial if you're an endurance athlete — such as a marathon runner, swimmer, cyclist or all three — preparing for an event that will last 90 minutes or more. Other athletes generally don't need carbohydrate loading. It's usually enough to get about half of your calories from carbohydrates.
Diet details
The role of carbohydrates
Carbohydrates, also known as starches and sugars, are your body's main energy source. Complex carbohydrates include legumes, grains and starchy vegetables, such as potatoes, peas and corn. Simple carbohydrates are found mainly in fruits and milk, as well as in foods made with sugar, such as candy and other sweets.
During digestion, your body breaks down carbohydrates into sugar. The sugar enters your bloodstream, where it's then transferred to individual cells to provide energy. Sugar is stored in your liver and muscles as glycogen — your energy source.
Increase your energy storage
Your muscles normally store only small amounts of glycogen — enough to support you during recreational exercise activities. If you exercise intensely for more than 90 minutes, your muscles may run out of glycogen. At that point, fatigue might set in, and your performance may suffer.
But with carbohydrate loading, you may be able to store more energy in your muscles. This may give you the stamina to make it through longer endurance events. But, you'll still need to consume some energy sources during your event.
Carbohydrate loading
Carbohydrate loading is done the week before a high-endurance activity. One to three days before the event, increase your carbohydrate intake to about 8 to 12 grams of carbohydrate per kilogram of body weight. Cut back on foods higher in fat to compensate for the extra carbohydrate-rich foods.
Also scale back your training for three to four days before the event. The combination of eating more carbohydrates and tapering activity appear to boost muscle glycogen stores.
How many carbs you need depends on your total calorie goal as well as your sport. For most athletes, 5 to 7 grams of carbohydrate per kilogram of body weight daily is right for general training. (Note that 1 kilogram equals 2.2 pounds.) Endurance athletes may need up to 12 grams per kilogram.
Sample carbohydrate-loading meal plan
Here's a sample carbohydrate-loading meal plan for an athlete who weighs 170 pounds (77 kilograms). It's based on 4.5 grams of carbohydrates for each pound (10 grams per kilogram) of body weight.
You can tweak this sample carbohydrate-loading meal plan to suit your own tastes and nutritional needs.
