Energy bars and energy gels aren't the same. You use energy gels during or just after a run, workout, or race to replenish glycogen (carbohydrate stores) in your muscles. Energy bars are meant to be a healthy equivalent to candy bars: handy to carry with you yet dense in calories, high in carbohydrates, and lower in fats than candy bars. They're ideal for cyclists and hikers who need a convenient food that's going to give them many calories, thus eliminating the need to eat much else.

For runners, though, energy bars don't make much sense. Because you don't eat while you run (with the exception of energy gels on certain runs), you would eat an energy bar at other times of the day, when you can just as easily eat a banana, whole-grain bagel, homemade healthy cookie, carrots, or something similar. Energy bars aren't as healthy as other foods, and they're certainly more expensive.