Sports Nutrition: Facts behind carb loading

The pre-race carb-loading spaghetti dinner has become a well-known part of many endurance events. Why carb load? When do you start carb loading and how long does it take? What are the best foods to eat for carb loading? How much carb do you need eat?

The pre-race carb-loading spaghetti dinner has become a well-known part of many endurance events. Why carb load? When do you start carb loading and how long does it take? What are the best foods to eat for carb loading? How much carb do you need eat? The Three Amigos, especially Lauren and Marc, can use the following tips to maximize carb stores in the few days prior to the Bayshore and make sure they are fueled up to achieve their race goals.

What is carb-loading?

Carbohydrate (carb) loading is a strategy to boost the bodyâ??s carb stores.

Carb energy is stored as glycogen, in the muscles and liver. Carb is the body's primary fuel source during a marathon as more energy can be produced from carbs than fat during this type of exercise! And itâ??s not just your muscles that need carb fuel for stamina; your brain needs it to keep you alert and focused on your goal too.

Typical glycogen (carb) stores only fuel the body for 90 minutes, depending on training status, exercise intensity and duration.

Carb-loading allows muscle to super compensate with glycogen, which means you are better fueled to maintain your target race pace to the finish line!

What are the benefits of carb-loading?

Carb-loading helps improve athletic performance, especially for moderate to high intensity exercise lasting 90 minutes or longer. Research has shown that carb-loading can delay the onset of fatigue and extend the time at which you can maintain a steady pace by as much as 20%.

When is the time-frame for carb-loading?

Carb-loading can be accomplished in a window of 24 -hours up to 72 -hours just prior to the event through a combination of exercise taper (rest) and a high carb fuelling plan.

Then (1960â??s): The "original" carb-loading practice included 3-4 days of glycogen depletion (hard training on low carb intake) followed by 3-4 days of carb loading (progressively less training on high carb intake) to maximize muscle glycogen (carb) stores.

Now (2010â??s): Research has shown that a depletion phase is no longer necessary.

Even if this is your first marathon, we now know that trained individuals routinely deplete glycogen stores, which makes the muscles constantly primed for carb-loading.

What are the best carb-loading foods?

Whether you have 24 or 72-hours to taper training and prepare for the race, optimizing carb intake is a key strategy. Choose lean proteins and eating carb-rich foods that are lower in fat and fiber.

· While we typically recommend fiber-rich foods to support a healthy lifestyle and long-term training needs, high fiber foods may slow digestion and lower total carb availability during the carb-loading phase.

· High fat foods may also lead to lower carb availability and like fiber, delay stomach emptying, which may cause stomach upset during the event.

Eat more of:

· Low fat milk & fruited yogurt

· Fruit â?? fresh, peeled, canned or pureed; 100% fruit juice

· Starchy vegetables â??peeled potatoes, pumpkin, peas

· Grains â?? cereal, rice, bread& pasta

Eat less of:

· High fiber cereals & breads

· Legumes

· Fruit & veggie skins

· Fried foods

· Creamy sauces

· Nuts & seeds

If your appetite is low, refined, concentrated sources of carb that may help you achieve your carb-loading goal include:

· Hard or gummy candy

· Seedless jam and fruit jellies

· Fruit leathers

· Honey and syrups

· Regular soft drinks

With all new eating strategies, it is important to practice your

carb-loading plan for tolerance of foods and quantity ahead of time.

How much carb is needed for carb-loading?

During the carb-loading phase, eating as much as 8 â?? 12 grams of carb/kg is typical to maximize muscle carb levels. Along with carb-rich meals and snacks, rest is vital to achieve successful carb-loading in the 24-hours prior to an endurance event. If you cannot taper your training to resting level within 24 â?? 36 hours of the event, aim for a carb intake in the upper range of 10 â?? 12grams carb/kg.

For example, the carb-loading meal plan for a 60 kg (132 lb.) athlete should provide approximately 600 g carb/day or for a 75 kg (165 lb.) athlete, 750 g carb/day, plus rest, to maximize muscle carb stores.

On the morning of the race, it is critical to pay attention to your pre-race meal. Eating about 200-300 grams of carb, 2-4 hours prior to the start is important to top up liver glycogen (carb) stores used overnight and any muscle stores not yet fully loaded. Eating before the race will also help prevent hunger and provide hydration pre-event. While carb foods that provide slow release of energy may be useful, the most important factor in the pre-race meal is to eat a sufficient amount of well-tolerated carbs to prevent low energy during the event.

What about hydration during carb-loading?

Being well hydrated is essential for optimal athletic performance. Beverages and liquid foods can be an important source of both carbs and fluids during carb-loading. Carb containing liquids to include:

· Plain and flavored low fat milk

· 100% fruit juice

· Smoothies

· Sports drinks

· Regular soft drinks

Liquid carbs, such as sports drinks, may also improve tolerance when topping off carb stores and fluids in the moments before the start of the event.

As glycogen (carb) is stored in the muscle with water, the carb-loading process promotes a small amount of water retention and weight gain. Therefore, it is normal to expect up to 2 kg of weight gain if you have carb-loaded successfully.

Carb-loading Sample Menu

(600 grams carb)


2 packets of plain instant oatmeal

2 Tablespoons brown sugar

3/4 cup blueberries

1 cup low fat milk

2 slices toast

2 Tablespoons jam


1 cup low fat fruit yogurt


1 ½ cups cooked couscous

½ cup cooked green peas

½ cup cherry tomatoes, halved

1 Tablespoon each lemon juice and olive oil

Tuna (pouch, packed in water)

3 low fat fruit filled cookies

1 ½ cups 100% fruit juice


1 fruit cup

1 ½ cups chocolate milk


2 cups pasta

1 cup diced sweet potato

1 cup marinara sauce

1 cup spinach

Lean Italian turkey sausage

1 Baked apple with ½ cup low fat frozen yogurt



1 toasted waffle

2 Tablespoons maple syrup

For optimal results, consider working with a registered dietitian who specializes in sports nutrition to help you develop a carb-loading plan specific to your needs. Contact Miranda Monroe via
for a consultation to put the science of sports nutrition on your plate with a personalized plan and practical meal planning strategies to help you achieve your performance goals.
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