Carbo-loading: Tips for Endurance Athletes

author : Nancy Clark
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While carbo-loading sounds simple (just stuff yourself with pasta, right?), the truth is that many endurance athletes make food mistakes that hurt their performance.

The Athlete’s Kitchen
Copyright: Nancy Clark, MS, RD, CSSD

Does carbo-loading mean stuffing myself with pasta?
Should I avoid protein the day before the marathon?
Will carbo-loading make me fat…?

If you are an endurance athlete who is fearful of “hitting the wall,” listen up: proper fueling before your marathon, triathlon, century bike ride or other competitive endurance events can make the difference between agony and ecstasy! If you plan to compete for longer than 90 minutes, you want to maximize the amount of glycogen stored in your muscles because poorly fueled muscles are associated with needless fatigue. The more glycogen, the more endurance (potentially). While the typical athlete has about 80 to 120 mmol glycogen/kg muscle, a carbo-loaded athlete can have about 200 mmol. This is enough to improve endurance by about 2 to 3%, to say nothing of making the event more enjoyable.

While carbo-loading sounds simple (just stuff yourself with pasta, right?), the truth is that many endurance athletes make food mistakes that hurt their performance. The last thing you want after having trained for months is to ruin your performance with poor nutrition, so carbo-load correctly!

Training Tactics
The biggest change in your schedule during the week before your event should be in your training, not in your food. Don't be tempted to do any last-minute long sessions! You need to taper your training so that your muscles have adequate time to become fully fueled (and healed). Allow at least two easy or rest days pre-event.

Fueling Tactics
You need not eat hundreds more calories during race week. You simply need to exercise less. This way, the 600 to 1,000 calories you generally expend during training can be used to fuel your muscles. All during this week, you should maintain your tried-and-true high-carbohydrate training diet. Drastic changes can easily lead to upset stomachs, diarrhea, or constipation. For example, carbo-loading on an unusually high amount of fruits and juices might cause diarrhea. Too much white flour, low fiber bagels, breads, and pasta might clog your system. As Marathon King Bill Rodgers once said “More marathons are won or lost in the porta-toilets than they are at the marathon...” Fuel wisely, not like a chow hound.

Be sure that you carbo-load, not fat-load. Some athletes eat gobs of butter on a dinner roll, big dollops of sour cream on a potato, and enough dressing to drown a salad. These fatty foods fill both the stomach and fat cells but leave muscles poorly fueled. The better bet is to trade the fats for extra carbohydrates. That is: instead of devouring one roll with butter for 200 calories, have two plain rolls for 200 calories. Enjoy pasta with tomato sauce rather than oil or cheese toppings. Choose low-fat frozen yogurt, not gourmet ice cream.

Tools for Carbo-loading
When carbo-loading, you want to consume about 3 to 5 grams carbohydrates per pound of body weight. (This comes to a diet with about 60% of calories from carbohydrates.)

Divide your target grams of carbohydrates into three parts of the day (breakfast+snack; lunch+snack; dinner+ snack), and choose foods to hit your target!

Get a Food Log!
See BT's nutrition log to find out the calories in the foods you eat.
-> Instructions and Features

Meal Timing
NYC Marathon Queen Grete Waitz once said she never ate a very big meal the night before a marathon, as it usually would give her trouble the next day. She preferred to eat a bigger lunch. You, too, might find that pattern works well for your intestinal tract. That is, instead of relying upon a huge pasta dinner the night before the event, you might want to enjoy a substantial carb-fest at breakfast or lunch.


An earlier meal allows plenty of time for the food to move through your system. You can also carbo-load two days before if you will be too nervous to eat much the day before the event. (The glycogen stays in your muscles until you exercise.) Then graze on crackers, chicken noodle soup, and other easily tolerated foods the day before your competition.

You'll be better off eating a little bit too much than too little the day before the event, but don't overstuff yourself. Learning the right balance takes practice. Hence, each long training session leading up to the endurance event offers the opportunity to learn which food—and how much of it—to eat. I repeat: During training, be sure to practice your pre-event carbo-loading meal so you’ll have no surprises on the day of the event!

Weight Gain
Athletes who have properly carbo-loaded should gain about one to three pounds—but don't panic! This weight gain is good; it reflects water weight and indicates you have done a good job of fueling your muscles. For every ounce of carbohydrate stored in your body, you store almost three ounces water.

Be sure to drink extra water, juices, and even soda pop, if desired. Abstain from too much wine, beer, and alcoholic beverages; they are not only poor sources of carbs, but they are also dehydrating. Drink enough alcohol-free beverages to produce a significant volume of urine every two to four hours. The urine should be pale yellow, like lemonade. Don’t bother to overhydrate; your body is like a sponge and can absorb just so much fluid.

Many endurance athletes eat only carbs and totally avoid protein-rich foods the days before their event. Bad idea. Your body needs protein on a daily basis. Hence, you can and should eat a small serving of low-fat proteins such as poached eggs, yogurt, turkey, or chicken as the accompaniment to most meals (not the main focus), or plant proteins such as beans and lentils (as tolerated).

Event day:
Carbo-loading is just part of the fueling plan. What you eat on the day of the event is critically important and helps to spare your limited muscle glycogen stores. So fuel yourself wisely both before and during the event—and hopefully you will enjoy miles of smiles!


If you weigh:Total #g carb/dayTarget grams of carbs per five hours:
7:00 a.m.-noon;
noon-5:00 pm;
5:00-10:00 pm
100 lbs300 to 500 g100 to 175 g
125 lb375 to 625 g125 to 210 g
150 lbs 450 to 750 g150 to 250 g
175 lbs 525 to 875 g175 to 290 g


Sample 50 gram carbohydrate choices for the foundation of a meal or snack:

-Wheaties, 2 cups
-Nature Valley Granola Bar, 2 packets (4 bars)
-Thomas’ Bagel, 1 (3.5 oz)
-Banana, 2 medium
-Orange juice, 16 ounces
-Apple, 2 medium
-Raisins, 1/2 cup
-Pepperidge Farm multi-grain bread, 2.5 slices
-Baked potato, 1 large (6.5 ounces)
-Pasta, 1 cup cooked
-Rice, 1 cup cooked
-Fig Newtons, 5
-Flavored Yogurt + 3 graham cracker squares

Two Sample Carbo-loading Food Plans (3,200-3,400 Calories)
Appropriate for a 150 pound athlete who needs about 4 grams carb/lb body weight.

Menu #1

FoodApproximate CaloriesCarbs (g)
Wheaties, 2 cups 22048
Milk, 1% lowfat, 8 ounces10012
Bagel, 1 (3.5 ounce30055
Cream cheese,  lowfat, 2 Tbsp502
Orange juice, 12 ounces16040
Breakfast Total:830 Calories75% Carb
Whole grain bread, 2 slices20040
Peanut butter, 2 tablespoons2008
Jelly, 2 tablespoons 10025
Fruit yogurt, 8 ounces 23035
Potato chips, baked, 2 ounces24045
Lunch Total:970 Calories65% Carb
Apple, 1 large12030
Graham crackers, 4 squares12022
Snack total:240 Calories90% Carb
Chicken breast, 5 ounces250 -
Rice, 1.5 cups cooked 30065
Broccoli, 1 cup5010
Dinner rolls, 2 whole wheat20040
Dinner Total:800 Calories60% Carb
Banana, 1 medium (4 ounces)   10025
Sherbet, 1 cup26045
PM Snack Total:360 Calories~100% Carb
TOTAL Menu #1 3200 Calories547g/~70% Carb
  ~4 g carb/lb for a 150 lb athlete

Menu #2

FoodApproximate CaloriesCarbs (g)
Oatmeal, 1 cup dry, cooked in 30055
Milk. 16 ounces20025
Raisins, 1/4 cup13030
Brown sugar, 1.5 tablespoons 5012
Apple juice, 8 ounces12030
Breakfast Totals:800 Calories75% Carb
Sub sandwich roll, 6” (4 ounces) 32060
Lean meat (4 ounces200-
Fruit yogurt, 8 ounces24040
Grape juice, 12 ounces 22055
Lunch Total:980 Calories80% Carb
Fig Newtons, 633065
Jelly beans, 15 large 15038
Snack Total:480 Calories85% Carb
Spaghetti. 2 cups cooked 40080
Prego spaghetti sauce, 1 cup25040
Italian bread, 2 slices15030
Root beer, 12 ounces14038
Dinner Total:940 Calories80% Carb
Canned peaches in syrup, 1 cup20048
PM Snack Total:200 Calories~100% Carb
TOTAL Menu #2 3400 Calories646gram/~75% Carb
  ~4.5 g carb/lb for a 150 lb athlete



Nancy Clark, MS, RD, CSSD is Board Certified as a Specialist in Sports Dietetics. She counsels casual and competitive athletes in her private practice at Healthworks, the premier fitness center in Chestnut Hill MA (617-383-6100).


Her Sports Nutrition Guidebook, Cyclist’s Food Guide, and Food Guide for Marathoners: Tips for everyday Champions all offer additional information about how to prepare for endurance events. See and for more details.


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date: November 20, 2006

Nancy Clark

Nancy Clark, MS, RD, an internationally known sports nutritionist and nutrition author, is a registered dietitian (RD) who specializes in nutrition for exercise, health and the nutritional management of eating disorders.

avatarNancy Clark

Nancy Clark, MS, RD, an internationally known sports nutritionist and nutrition author, is a registered dietitian (RD) who specializes in nutrition for exercise, health and the nutritional management of eating disorders.

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