Don't be deceived by their small size. Although some are high in fiber and protein, energy bars are not that far from candy bars. Snickers for example have less calories than a Clif's White Chocolate Macadamia Nut bar. A lot of energy bars contain high amounts of fructose, corn-syrup and added sugar. AKA not a good thing. Those bars tend to be low in nutritional value so, not only is it not very satisfying, but replacing a meal by an energy bar is not the healthiest idea. A Special K Blueberry Pastry Crisp, for instance, tends to leave you tired and hungry because it is high in refined carbs and low in fiber.