In 2008, New York City passed a law requiring some fast food and coffee chains to include calorie information on their menus. Other states and cities have followed suit, but information on the effects of these laws has been inconclusive. A recent study set suggests these laws have the beneficial effect lawmakers hoped.

In a recent Yale University study, when diners were given menus with calorie information, they ate lower calorie meals. And a label stating that 2,000 calories was the average recommended daily calorie intake amount caused diners to eat less during the rest of the day.

Diners in the group given the 2,000 calorie recommendation, when reporting their calorie consumption for the remainder of the day, reported eating about 250 calories less than the other groups.

The 303 diners in the Yale study were randomly given one of three dinner menus. One had no calorie information, the second had calorie information on the listed dishes and the third had both calorie information and a statement that the average adult should consume around 2,000 calories total in a day.

Diners in the two groups given calorie information ate 14% fewer calories. Diners in the group given the 2,000 calorie recommendation, when reporting their calorie consumption for the remainder of the day, reported eating about 250 calories less than the other groups. The 2,000 calorie recommendation stuck in their minds.

The idea behind restaurant calorie labeling is that a diner confronting a plate of fettuccine alfredo would know how many calories it contains and be more thoughtful about indulging in it. Such labeling would also allow diners to compare the calorie content of different dishes. The Yale study suggests that this information is quite helpful in reducing overeating and to diners looking for lower calorie alternatives.

Christina Roberto, the doctoral candidate who led the study, points out the importance of including the 2,000 daily calorie recommendation in the menu. That single line of information helped people see the meal in the context of their entire day. It also had a lingering effect that remained after the meal was over.

As of the moment, both healthcare bills being considered by Congress contain menu labeling provisions.

The results of the Yale study were published online ahead of print by the American Journal of Public Health on December 17, 2009.