What does that suggest? Either people don't notice what's in the food they buy, or they don't let the knowledge affect what goes in their mouths.
"You can certainly say that most people certainly don't understand the food label," former Food and Drug Administration Commissioner Lester Crawford told the 2004 World Obesity Congress. "And it's not because they can't understand it, it's because they don't care to understand it."
If people don't heed the information they already have, they aren't going to waste effort digesting an additional onslaught of facts. The assumption is that people eat badly because they don't acquire the essential knowledge about their food. But it may be they fail to obtain those facts because they prefer to eat whatever they like. Not everyone approaches dinner as a research project.
There is little research to suggest that calorie alerts will make any difference in obesity rates. In 2004, the American Journal of Preventive Medicine reported that when women of normal weight were given this kind of information, it had no effect on what they ate, and that facts furnished in restaurants were also irrelevant in dining decisions.
A study in the Journal of the American Dietetic Association found that people who dine out frequently are less likely to pay attention to nutritional data than people who eat mostly at home. It suggested that "those who have a less nutritious diet are less likely to use food labels and have less interest in doing so."
As anyone who's ever raised a teenager knows, continually bombarding people with information that is useful or even crucial to their well-being is not always productive. Menu laws may not increase our ability to make good food choices. But they will certainly improve our ability to tune out.