No one's claiming that prepackaged cereal bars—even fiber- and protein-packed ones—are the healthiest or most slimming snack choice (most contain more sugar than your dietician would recommend). But a study at the U.K.'s Cardiff University found that this ultra-convenient snack has its advantages if the alternative is an empty stomach. When women ate a cereal bar as a midmorning snack, especially if they hadn't eaten breakfast, they became much more alert and less anxious than those who didn't snack. Moreover, they showed an improved ability to remember words they had just learned—a likely result of the protein and a well-timed (and, er, significant) glucose rise.
How much: One standard fiber cereal bar (about 1.5 grams of proteins and fiber, and 3.5 to 4 grams of fat)
Extra perk: The Cardiff researchers also found that when people took a road test in the midmorning, those who had first eaten cereal bars perceived significantly more hazards—and were therefore likelier to avoid accidents—compared with non-snackers. (Bars are also easy to eat while driving one-handed.)
Next: The biggest mistakes women make when dieting