Since many races start at 8 a.m. or earlier, you'll have to set your alarm for a very early wake-up to hit that four-hour window. If that's not realistic, you may choose to eat your entire pre-race meal just two hours before the start.
But because you'll have less time to digest, eat only one gram of carbohydrate per pound of body weight—or 150 grams, or 600 calories, for a 150-pound runner—sticking with foods and liquids you know are very easy on your stomach. Since you're consuming less, you do risk running out of liver glycogen, which will cause your blood sugar to plummet and may mean you hit the wall. So be vigilant about fueling early in the race—consuming 30 to 60 grams of carbs per hour—to keep your energy levels high.
Finally, have your last 25 to 30 grams of carbs 30 to 60 minutes prior to the start. This could be an energy gel or chews, with 12 to 16 ounces of water or 16 ounces of sports drink.
"This provides the last shot of fuel to hold you over until you get into the rhythm of fueling mid-race," says Berning.
Berning also stresses that every runner has different food and fluid tolerances, which means a plan that works for one runner might spell GI disaster for another—follow these nutritional tips that prevent midrun stomach trouble.
That's why it's key that you practice your pre-race meal strategy during training.
"The stomach and gut need to be trained to handle food before a long run," says Berning.
She suggests trying different combinations to find the one that works best for you. And once you find the perfect mix, stick with it.
"Eat the exact same meal on race morning that you practiced with in training," says Wilson, "and you'll be set."