Training Guide: Running a Half-Marathon

The Truth About Carbo Loading

Does all that pre-race pasta really buy you extra oomph at the starting line? "The trick is to pack in carbs throughout training -- not just the night before," says Nancy Clark, RD, author of Nancy Clark's Food Guide for Marathoners. The harder you train, the more carbs you'll need to boost muscle stores of glycogen (aka runner's fuel).

"Eat a meal with carbs and protein within an hour after each long run," Clark says. "And starting two or three days before your race, consume three to five grams of carbs per pound of your total body weight per day." Top off your tank an hour or so before the race with carbs that settle easily, such as a bagel with a little bit of peanut butter.