We don't really know for sure, writes U.S. News blogger David Katz. Studies of calorie count postings to date have yielded rather mixed results. There is some evidence to suggest that calorie counts on foods and beverages do give consumers pause, and a bracing reality check. These, in turn, may help dial down total calorie intake.
But that effect is by no means established. In some cases, calorie counts appear to evoke defiance (or denial) rather than temperance. And there is some evidence to suggest that calories avoided at one time may simply find their way back into the diet at another. There is, as well, some research evidence that when people expect to be left hungry—a potential effect of a low-calorie count on display—that hormones respond accordingly, making the expectation a self-fulfilling prophecy. Maybe a bit of ignorance is the belly's bliss. [Read more: Soda, Calories, and a Full Accounting]