Turns out, if you haven't been to a fast- food restaurant lately, you're an exceptional human being, or an exceptional Californian at any rate. A consumer survey last year found that 4 out of 5 adults in the state's largest market areas (Los Angeles, Fresno, Sacramento, San Diego and San Francisco) made fast-food purchases at least once a month, and on average 3.44 times a week, or just about once every two days.
Using those numbers, the researchers used a simple formula to calculate how many calories an average fast-food eater might not eat if the proposed law is passed: (52 calories saved per visit) x (3.44 visits per week) x (52 weeks in the year), which comes out to about 9,300 calories per year.
Because consuming 3,500 excess calories translates to 1 pound of weight gain, cutting out 9,300 calories would make a person's weight about 2.7 pounds less at the end of a year than it would be otherwise.
That might not sound like a lot, Bloom says. "But from a public health perspective, we just need a good number of people making small changes." After all, 2.7 pounds multiplied by millions of people starts to add up.
The calculation above assumes that the person would see the calorie information. It also assumes that restaurants won't make any changes to items on their menus -- although it seems likely that they will, says Margo Wootan, director of nutrition policy at the Center for Science in the Public Interest.
If so, the law's slimming effects could be even greater.
Legislation has been the mother of product reformulation before, for instance, when trans-fat labeling was required on food packages.
"There's been a 50% decrease in the amount of partially hydrogenated oil used in North America," Wootan says. "We hope and expect that chain restaurants will reformulate their offerings to reduce calories or offer half-portions or whatever."
But there are still open questions.
For example, who's to say that people won't make up for the calories they don't eat at fast-food restaurants by eating more later?
And who knows if 37% of people who see the calorie information will make different choices because of it, as did the Subway customers in the New York study?
There is some evidence that this figure may be high.
A number of studies have shown that typically only 15% to 20% of people pay attention to labels.
But Yale's Brownell thinks the law would still be a plus. Even if calorie information doesn't make any difference, he says, "there's still the issue of the consumer's right to know."
In 2007, the Field Research Corp., which does marketing and public opinion research, polled 523 registered voters and reported that 84% of Californians say they want to know about calories and other nutritional content in restaurant food.
And whatever they do with that information if they get it, says Michael Jacobson, executive director of the Center for Science in the Public Interest, "I don't think they're going to be eating more food."