Restaurant menus that include kilojoule information do seem to encourage diners to exercise some restraint, a new study suggests.
What's more, researchers found, menus that give added information -- namely, the number of kilojoules the average adult should get in a day -- could prove even more effective at curbing appetites.
The findings, reported in the American Journal of Public Health, give some weight to the growing movement to require restaurant chains to place calorie information on their menus and menu boards.
In 2008, New York City became the first US city to mandate such changes at fast-food and coffee chains. That law became a model for California and other US states and cities that have since implemented or are considering similar measures. And soon the federal government may be stepping in; provisions for menu labeling are part of the healthcare reform legislation currently before Congress.
The intention is to help combat the nation's obesity problem by raising consumer awareness of just how many kilojoules lurk in their burgers, sandwiches, fries and desserts.
But questions have been raised about the effectiveness of menu labeling.
How the study was done
In October, an independent study of New York's law concluded that menu labeling had done nothing to change consumer habits in the city's low-income neighbourhoods. Shortly thereafter, the city's health department released preliminary data from a larger study suggesting that New Yorkers had, in fact, started buying fewer kilojoules at nine of 13 fast- food and coffee chains included in the research.
For the current study, Yale University researchers tested the effects of menus that provide not only calorie content, but also a line stating that the average adult should get about 8 400 kilojoules a day.
The researchers randomly assigned 303 adults to order from one of three menus: one with no kilojoule labeling; one with kilojoule information; and one with kilojoule content, plus a label with the kilojoule recommendation.
What the study showed
Overall, the study found, diners in the two kilojoule-label groups ate 14% fewer kilojoules at the meal than those who had ordered from the label-free menus.
And when study participants later reported on their food intake for the remainder of the day, the researchers found that those who had seen the kilojoule recommendation downed fewer kilojoules than those in the other two groups.
The setting was experimental, and not "real world," but that allowed the researchers to show cause-and-effect, noted Christina Roberto, a doctoral candidate at Yale who led the study. "We can say that is the menu labeling having the effects" on kilojoule intake, she said.
Moreover, Roberto said, the findings highlight the potential impact of a simple line stating the number of kilojoules a person should get each day.
"That turned out to be really important," said Roberto, noting that the information helps people put their single meal in the context of a whole day. "By putting that 'anchor' in," she said, "you can maximise the effectiveness of menu labeling." - (Reuters Health, December 2009)