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Endurance athletes have long touted the benefits of carbo-loading – which, for most, simply involved ingesting lots of pasta and bread the night before a race and calling it good. A smart carb-cramming plan, however, is slightly more strategic.

Research suggests, for example, that starting to ramp up carb intake a few days before an event can provide the best results. It also shows that by carbing up properly, an athlete can maximize endurance, maintain focus and improve strength.

Carbo-loading – the practice of increasing one’s intake of carbohydrates, particularly for a performance-related event or intense training session – is critical for endurance athletes. Carbo-loading tops off muscles’ glycogen stores, which power your muscles for maximum performance. The more glycogen you have socked away, the longer you’ll last. And those who exercise hard enough to deplete their muscles of glycogen (a process that generally takes 60 to 90 minutes of strenuous exercise, so think runners, cyclists and cross-country skiers – not low-key walkers or joggers) will need more than their usual dose of carbs to keep them going.

A Method to the Macaroni

Carbo-loading works best when you’ve already been eating a carbohydrate-rich diet during your training regimen, according to the Mayo Clinic, because during that time your body has learned to use the carbs you eat more effectively. In fact, research from the Human Performance Laboratory at Ball State University in Muncie, Ind., suggests that well-trained athletes who log long training sessions teach their muscles to store up to 25 percent more glycogen.

Ideally, endurance athletes’ diets should already be carb-rich, so carbo-loading mainly consists of bumping up your ratio of carbs to fats and proteins even further. You shouldn’t take in more calories; rather, just eat more oatmeal, fewer eggs, more potatoes, less steak. A week before your event (when, ideally, you’ll begin the carbo-loading process), you should also reduce the intensity and duration of your workouts in order to rest and rebuild your muscles.

During your carbo-loading phase, carbs should constitute about 60 to 70 percent of your daily caloric intake. Specifically, shoot for 3 to 5 grams of carbohydrates per pound of body weight each day. So, a 130-pound woman would need from 390 to 650 grams of carbs in her diet per day, and a 180-pound man would strive for 540 to 900 grams per day. (At the beginning of your loading cycle, start at the lower end of the range; by the end, strive for the higher end.)

Keep in mind, though, that carbo-loading isn’t an excuse to scrap your nutritional needs: It’s important to maintain a healthy diet that includes vitamin- and mineral-packed foods such as fruits, veggies and legumes. According to the Mayo Clinic, about 10 to 15 percent of your non-carb calories should be from lean protein in meat, poultry or fish, and about 15 to 20 percent of your calories should come from healthy fats.

Load Your Own Way

Carbo-loading isn’t just for high-stakes competition, according to sports nutritionist Monique Ryan, MS, RD, author of Sports Nutrition for Endurance Athletes. She notes that both athletes and fitness enthusiasts should experiment with carbo-loading throughout their training.

Every body responds to carbs a little differently, so your training cycle is the perfect time to figure out what your body likes and digests the best.

Generally, complex sugars, such as those in whole-grain pasta or an apple, are absorbed by your system more slowly than the simple sugars found in a white-flour bagel or cookie. That means complex carbs deliver more long-lasting energy. Simple sugars, on the other hand, provide a quick burst of short-lived fuel for your muscles’ energy needs, but they don’t usually offer much nutritional value.

To each his own digestive system, however. “All carbs have their own unique glucose and insulin curve in each individual,” notes Ryan. The point is, what works best for your training partner might not be ideal for you.

Keep It Clean

Carbo-loading priorities aside, when it comes to nutrition, the old rule still applies:

“In general, athletes want to focus on quality carbs from fruits, vegetables and wholesome grain foods for the bulk of their carbohydrates. These nutrient-dense foods offer not only the fuel needed for top performance, but also the vitamins and minerals that are like spark plugs for the body’s engine,” says Nancy Clark, MS, RD, a Boston-area sports nutritionist and author of Nancy Clark’s Sports Nutrition Guidebook.

Athletes don’t necessarily have to avoid sugar altogether. Most dietitians assert that it’s acceptable for them (like everyone else) to take in up to 10 percent of their calories from refined sugars. For the athlete who eats 3,000 calories per day, that might equate to a midafternoon Frappucino or ice cream for dessert. But if you’re eating processed energy bars or shakes for training, or nursing a soda habit, you could easily be getting your sugar quota that way, too.

Read labels carefully, and remember, because refined sugars are a pro-inflammatory (and thus antirecovery) food, and because they tend to reduce your immunity, you’re best off minimizing your refined-sugar intake as much as possible. Try the natural supplement stevia for everyday sweetening, and save your sugar for feel-good treats you really enjoy.

Calculating Carbs

It’s a good idea to know which foods provide the biggest carbohydrate bang per serving, but you don’t necessarily have to approach each meal with a fork and a calculator. Marathoner Deena Kastor, who won bronze at the 2004 Olympics, believes that once you understand how your body processes different carbohydrates – that is, which foods provide lasting energy for you – you can approach your meals with an intuitive sense of what you need.

“I focus on adding another heaping spoonful of pasta or a few more potatoes,” she says. “Before the Athens marathon, I also ate a lot of dense fruits with high sugar content: pears, bananas, grapes. They replaced a lot of electrolytes and minerals I knew I was sweating out.”

But while emphasizing fruits might work for Deena, Clark warns that, for some athletes, the fiber content in some fruits might result in unwanted pit stops along the racecourse. Generally, though, the more adjusted your body is to eating whole foods, the less of a problem this is likely to be.

Common Mistakes

As you perfect your personal carbo-loading plan, there are certain things to avoid. For instance, research supports skipping the “depletion phase” of classic carbo-loading. The old-school depletion approach included hard workouts a week or so before competition to drain the muscles of glycogen, followed by a few days of a low-carb diet to further sweep out the shelves. In the final few days before the race, adherents then switched to a high-carb diet to saturate the muscles with glycogen.

While that approach does work, a study published in the International Journal of Sports Medicine in 1981 found that eliminating the depletion phase works just as well and can prevent athletes from feeling sluggish and irritable the week of their event. “The depletion phase accomplishes no more than what simply resting and eating properly does,” Ryan says.

Other tried-and-true advice you can take to the table:

1. Don’t experiment with new foods during the week before competition. If you’re traveling to an event and are tempted to try the local fare, hold off until after the race.

2. Skip the high-fiber foods the day before the event. Unless you are used to eating them as part of your regular diet and know you tolerate them well, raw vegetables, beans, bran and the like may leave you feeling bloated and gassy when the gun goes off. Also, avoid fatty foods that take a long time to digest. Stick with high-carb, easily digestible foods like pasta and fruit.

3. Don’t obsess about weight gain. Proper carbo-loading will cause you to put on a little weight, because with each gram of glycogen your muscles store about 3 grams of water. “A well-loaded athlete will gain about 2 to 4 pounds of water weight,” Clark says.

Burn, Bagel, Burn

“Carbo-loading will provide higher-than-normal glycogen stores,” Ryan says, “but even ‘fully loaded’ marathoners will lose steam between miles 15 and 20. If you’re exercising for that long, you’ll still have to take in carbohydrates during the event.”

An hour or so into a training session or competition, it’s wise to begin refueling your muscles with glucose. At this point, whether you eat a cookie or ingest a sports gel doesn’t really matter, although packets of gels and other foods designed for eating and drinking on the go are convenient to carry, go down quickly and tend to be easily digestible.

If you’re eager to stretch your glycogen stores and your athletic potential to the max, keep these carbo-loading guidelines in mind: Experiment with your carb intake during your training routine, start carbo-loading well before race day, and push the carbs while controlling your calories and nutrition. Do this on a regular basis and you’ll find that carbo-loading isn’t much different than any other aspect of race preparation: It all comes down to practice, practice, practice. 

What to Eat When Carbo-Loading

Training experts recommend that endurance athletes amp up energy stores in the muscles before a competition and before long training sessions. About a week out from your big event, your daily caloric intake should shift to 60 to 70 percent carbs. An easier calculation: For every pound of body weight you carry, consume 3 to 5 grams of carbs daily. As you tally up the grams, consider these carbohydrate-rich choices:

Food item Carbs (grams) Calories per serving Percent carbs
1 cup cooked pasta 56 g 300 78
4 fig bars 44 g 224 78
2 slices whole-wheat bread 26 g 138 71
3/4 cup cooked brown rice 34 g 162 85
1 cup low-fat vanilla yogurt 34 g 208 62
1/4 cup of raisins 33 g 123 96
1 cup dry organic cereal with nonfat milk 34 g 157 79
1 serving oatmeal (1/2 cup dry) 29 g 133 79
1 cup orange juice 25 g 110 89
1 ounce whole-wheat pretzels 23 102 83

Information from

This article originally appeared as “Carbo-Loading Lessons” in the November 2005 issue of Experience Life.

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