On Tuesday, the Food and Drug Administration released new rules on the labeling of calories on restaurant menus. The changes are sweeping: Any restaurant with 20 or more locations, movie-theater chains, amusement parks, meals sold in grocery stores, and vending machines will all be required to label calorie amounts on food options. There is no exception for alcohol ordered from a menu (mixed drinks ordered at the bar, however, will continue to not have calorie information). The rules take effect a year from now, although vending machine operators will have two years to comply.

The intention is to change consumer behavior (i.e., make us less fat). For some, it will be harder to ignore the fact that a large popcorn at the movies contains about 1,200 calories. To add context to calorie counts, the FDA will also require menus to contain the following message: "2,000 calories a day is used for general nutrition advice, but calorie needs vary."

More information will certainly not hurt consumers. But the evidence that calorie counts on menus actually change behavior is not conclusive. One study in Starbucks chains found that calorie counts reduced the amount of calories per transaction by 6 percent. Another in McDonald's stores found no significant change in consumption behavior. Calorie labels on restaurants are marginally effective, at best.

Here's why. Calorie information may be helpful to the people who are already health conscious, but they do not necessarily aid decision-making in people who aren't. Which is a problem, because it is the people who are not health conscious who are the intended targets of the regulations. It's hard for people to put the calorie information about one item into the perspective of a daily diet—even when they are told 2,000 calories is the recommended daily amount. It takes a lot of mental math (what did I eat for breakfast, what do I plan to eat for dinner?) which is hard to do while waiting in line at a McDonalds, for instance. In one study, while 30 percent of participants said they read nutrition facts when making food purchasing decisions, eye-tracking devices revealed that only 9 percent actually did.

The research suggests that if you want people to eat better, don't make them do math. One promising study out of Johns Hopkins found that when you tell consumers how many minutes of walking or jogging it would take to work off a food item, they made more healthy decisions.

But maybe there's hope for the FDA rules. Perhaps by saturating the environment with information, doing the math will get a bit easier. When this information is available at the grocery store, at the movies—at all the places we regularly consume food—it might become harder to ignore.

Or perhaps with all the nutritional noise, consumers will just tune it out.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.