A carbohydrate-loading diet, also called a carb-loading diet, is a strategy to increase the amount of fuel stored in your muscles to improve your athletic performance.
Carbohydrate loading generally involves greatly increasing the amount of carbohydrates you eat several days before a high-intensity endurance athletic event. You also typically scale back your activity level during carbohydrate loading.
Any physical activity you do requires carbohydrates to provide you with 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 to complete an endurance event with less fatigue, improving your athletic performance.
Carbohydrate loading is most beneficial if you're an endurance athlete — such as a marathon runner, swimmer or cyclist — preparing for an event that will last 90 minutes or more. Other athletes generally don't need carbohydrate loading. It's enough to eat a diet that derives half or more of its calories from carbohydrates.
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 converts 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, you may start to become fatigued, and your performance may suffer.
But with carbohydrate loading, you may be able to store up more energy in your muscles to give you the stamina to make it through longer endurance events without overwhelming fatigue. You still will need to consume some energy sources during your event.
Two steps to carbohydrate loading
Traditionally, carbohydrate loading is done in two steps the week before a high-endurance activity:
- Step 1. About a week before the event, adjust your carbohydrate intake, if needed, so that it's about 50 to 55 percent of your total calories. Increase protein and fat intake to compensate for any decrease in carbohydrates. Continue training at your normal level. This helps deplete your carbohydrate stores and make room for the loading that comes next.
- Step 2. Three to four days before the event, increase your carbohydrate intake to about 70 percent of your daily calories. Cut back on foods higher in fat to compensate for the extra carbohydrate-rich foods. Also scale back your training to avoid using the energy you're trying to store up. Rest completely the day before your big event.
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 weight daily is right for general training. However, endurance athletes may need 6 to 10 grams per kilogram. (1 kilogram equals 2.2 pounds.)
Sample carbohydrate-loading meal plan
Here's a sample carbohydrate-loading meal plan for an athlete who weighs 170 pounds (77 kilograms). Based on 4 grams of carbohydrates for each pound of body weight, the meal plan consists of about 70 percent carbohydrates. You can tweak this sample carbohydrate-loading meal plan to suit your own tastes and nutritional needs. Keep in mind that 1 gram of carbohydrates has 4 calories.
|Sample carbohydrate-loading meal plan
|Item (amount)||Carbohydrates (grams)||Total calories
|Milk, fat-free (12 ounces)
|1 oat bagel (4 1/2-inch diameter)
|Peanut butter, smooth (1 tablespoon)
|Honey (1 tablespoon)
|2 fig bars (3-inch bars)
|Grape juice, from concentrate (8 ounces mixed with 4 ounces water)
|Raisins (1 1/2 ounces)
|Milk, fat-free (12 ounces)
|4 slices whole-wheat bread (1 1/2 ounces per slice)
|Chicken breast, roasted without skin (4 ounces or 1/2 breast)
|Romaine lettuce, shredded (1/4 cup)
|4 thin tomato slices
|Mayonnaise-type salad dressing (2 tablespoons)
|Tortilla chips, low-fat, baked (1 ounce)
|12 baby carrots
|Low-fat fruit yogurt (8 ounces)
|10 wheat crackers
|2 medium apple
|Cranberry juice, unsweetened (12 ounces)
|Salmon, baked (3 ounces)
|Brown rice (1 1/2 cups)
|Broccoli, steamed (1 cup)
|Milk, fat-free (12 ounces)
|Iceberg lettuce (1 1/4 cups) with 5 cherry tomatoes and 1/4 cup shredded carrots
|Reduced-fat Italian salad dressing (2 tablespoons)
|Walnuts (1/4 cup)
|Wheat dinner roll (1 ounce)
|Strawberry slices (1/2 cup)
|Chocolate frozen yogurt, fat-free, sugar-free (1 1/2 cups)
Source: U.S. Department of Agriculture, Agricultural Research Service, 2012
Jan. 23, 2013
See more In-depth
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