Eating Tips Before and After Running - part of the women's fitness video series by GeoBeats. Eating Tips Before Running When you’re thinking about what to eat and when to eat before a long run, you want to eat maybe a full meal not less than three hours before your run, because otherwise, you know, you’ll get cramps and you’ll feel it in your stomach. About an hour, hour and a half before the run have something about 100 calories, a snack that is about 100 calories, like a banana, or half of an energy bar, half of a granola bar, something like that. Those are great snacks. You want to have something in your system, but not less than about an hour and a half before your run.