Perhaps one of the best benefits from training to run a 10K is the fact that you'll be able to eat more because you'll be burning more calories. In fact, you can roughly estimate just how many calories you'll incinerate per mile by multiplying your weight (in pounds) by 0.63 [source: Mueller]. Of course, you should strive for the usual healthy stuff -- whole grains, fruits and veggies, and lean meats -- because the better you fuel your machine, the better it'll perform on race day. It's a good idea not to eat any closer than one hour before a training run.
You also want to be sure to eat right both before and after a run, generally consuming foods (around 400 calories) that are higher in carbs before you exercise and recovering with a more balanced meal of carbs and protein.
On race day, your biggest worry nutritionally will be "hitting the wall" or "bonking," a condition whereby the body runs out of glycogen -- a type of stored energy your body will draw from while running. To avoid this, you can carbo-load in the week before the race by getting 70 to 80 percent of your calories from carbohydrates. Note: This doesn't mean you should eat 70 to 80 percent more food, just change the mix of the calories you're already eating to be more carb-heavy. On the big morning, eat a light meal of around 500 calories (like a bagel with cream cheese and jelly and a piece of fruit) about two hours before the run begins and you should be good to go -- and finish!