By: Melanie Flinn, MS, RD
Carbohydrates are a major source of energy in the body. Carb-loading, a practice that was developed in the late 1960s, refers to the method of consuming higher quantities of carbohydrates prior to a endurance event, in order to maximize muscle glycogen (energy) stores in the muscles. This strategy is followed, often by long distance runners and cyclists, to improve athletic performance.
Does it really help? Yes, but it’s not always done right.
Glycogen is your most readily accessible energy source, but it’s not the only one. Fat is also used, although not as efficiently as glycogen. To avoid “hitting a wall” your body relies on the energy from your glycogen stores. Once that runs out and you start breaking down fat for energy, your body will be working harder.
The Institute of Medicine’s 2005 Dietary Reference Intakes recommends 45 to 65% of calories come from carbohydrate. Active individuals require enough carbohydrates to maintain blood glucose and replace muscle glycogen expended during exercise. Endurance athletes need 6 to 10 grams of carbohydrates per kilogram of body weight, depending on duration, total energy expenditure, gender and environmental conditions. For endurance events, it is important to maximize muscle glycogen stores so it is ideal to start carb-loading 2 to 3 days in advance. Unfortunately, muscle glycogen cannot be filled up with just one meal!
Common carbs amongst runners are bagels, pasta, rice, oatmeal and potatoes; spaghetti squash, fruit and other ancient grains are also good choices. However, you don’t want to go overboard on the fiber prior to an event. Removing the peel from fruit and potatoes will help reduce the fiber. It’s also a good idea to maintain a lower fat diet as you are carb-loading which will be easier on your stomach on race day.
Carb-loading is only necessary for events longer than 90 minutes as that is the usual time that it takes for muscle glycogen stores to become depleted. As a rule of thumb, when exercising for more than 1 hour, 30 to 60 grams of carbohydrates should be consumed every hour. For endurance running, things like gels, energy bars, sports drinks can help meet this requirement.
Here is what a sample carb-loading meal would look like (150 lb person consuming the high end 10 grams of carbs per kilogram of body weight):
Breakfast
1 cup cooked oatmeal (cooked with milk) with 1/4 cup raisins and 1/2 tablespoon honey (76 gm)
1 cup fruit (30 gm)
8 ounce fruited yogurt (30 gm)
Snack
Muffin (50 gm)
Lunch
Loaded baked potato with veggies and corn (50 gm)
Orange slices, 1 large (22 gm)
1 cup chocolate milk (31 gm)
1 package fruit snacks (17 gm)
Snack
Banana with 2 Tablespoons nut butter (27 gm)
Sports bar (41 gm)
Sports drink (34 gm)
Dinner
Salmon
Pasta (2 servings) with marinara sauce and 1 cup spaghetti squash (114 gm)
2 Dinner rolls (40 gm)
Green salad, plus dressing (10 gm)
10 ounces Orange juice (31 gm)
Snack
2 fig bars (40 gm)
1/2 cup fruit (15 gm)
1 cup milk (12 gm)
Total 670 grams of carbohydrates (range for 150 lb person would be 409-682 grams)
Other things to consider:
- You might gain a few pounds during the carb-loading phase, likely as a result of the weight from extra muscle glycogen and water.
- Carbohydrate loading requires an exercise taper, which most athletes plan to do for the week prior to an event.
- Avoid too much protein and fat as you make room for the extra calories from carbohydrates.
- Consider working with a dietitian if you have questions about how to personally get enough carbohydrates into your diet.
Melanie is a Registered Dietitian and mom of four, with extensive experience in wellness and weight management. By combining her passion of food, nutrition and exercise, Melanie encourages her clients to have a healthy and happy relationship with food. She holds a BS in Nutrition from the University of Texas and a Masters degree in Nutrition from Boston University. She is the author of the blog Nutritious Eats where you can find healthy family recipes, nutrition and fitness tips and more. When she is not cooking or blogging, you can find her chasing her children around, running, doing yoga, and practicing photography.