On the high GI (glycemic index), scale, are energy bars really any better for us than a candy bar, or even a slice of processed-to-death white bread? Advertisements for some energy bars claim an energy boost without a sugar crash, for a more sustained and powerful workout. Kent State University researcher Steve Hertzler found that your basic PowerBar produced a faster energy peak, occurring 30 minutes after eating, than either Snickers candy bars or Wonder bread, which both peaked after 45 minutes. PowerBars also produced a steeper decline in blood glucose (aka sugar crash) after peaking than either the candy bar or the white bread. Ironman PR Bar, a moderate-carb energy bar with 40 percent carbohydrates, 30 percent protein, and 30 percent fat, peaked after 30 minutes with a lower, more sustained energy boost. Bottom Line: A high-carbohydrate energy bar may work for athletes wanting quick energy for short-duration exertion, says Hertzler, but a moderate-carbohydrate energy bar may be better for fueling endurance activities, (and for post-workout recovery fuel) or for anyone with diabetes.