If you tend to work out in the afternoons or evenings, or complete multiple sessions in one day, you should have fuel in the tank to sustain your efforts. If it’s been a couple of hours since you’ve eaten, it’s a good idea to top off your fuel tank before you train with a small snack of refined carbohydrates.
Working out first thing in the morning can be trickier. If you rise in the morning for a 60-minute run but never consume anything prior to heading out, drink half a cup of white grape juice, Benardot recommends. Once you’ve adjusted to that, slowly increase the amount to one cup, then add half a piece of white bread, then a whole piece, until you can tolerate two pieces of bread with one cup of juice—depending on duration of the activity. “You have to feed the beast in a way that it can tolerate fuel,” advises Benardot.
Austin recommends a low-glycemic sports drink or white toast with creamy, not crunchy, peanut butter if heading out on a higher intensity or longer run. If the session is low intensity or brief and it’s difficult to find something the runner’s stomach will tolerate, she’s fine with not eating beforehand. Through her work with various Olympic-caliber athletes, including 2004 Olympic marathon silver medalist Meb Keflezighi, Austin advises that the following foods tend to sit well prior to prolonged exercise: grits mixed with a little egg, a plain waffle with sliced bananas, bread with cream cheese, or even dried fruits.