Don't Count on Calorie Counts THE chicken salad hero at Lenny's, a chain in New York, has 213 more calories than the tuna salad on the same kind of bread. I did no research to bring you this information. On the big menu board at the Lenny's around the corner from me, where I sometimes grab a perfunctory lunch, the calorie counts of every item are clearly posted. The city made this mandatory for such restaurants about five years ago, hoping that informed gluttons might be reformed gluttons: that if we had more knowledge about where our efforts to slim down were going wrong, we'd have more power to change them. And yet four out of every five lunches at Lenny's, I get the chicken salad, all 879 calories of it, because there's something more persuasive than nutritional data. It's called mayonnaise. I can taste it in the chicken salad but not in the leaner tuna, partly explaining the extra damage - and the exaggerated siren's call - of the former. The stomach wants what it wants, even if the love handles pay a pendulous price for it. McMuffin by McMuffin, Frosty by Frosty, we Americans are waddling toward the moment when calorie counts like the ones at Lenny's are posted in every chain restaurant across the nation. Starbucks, which already advertises such information in cities that require it, announced last week that it would do so throughout the country before the end of this month, a recognition that the clock was ticking anyway. As part of the Affordable Care Act, any restaurant in America with at least 20 locations must follow Starbucks's lead, perhaps next year. The precise date hasn't been fixed. Soon enough, those of us taking in more calories than we should be and wearing pants roomier than we'd like to won't be able to say we weren't told. But is ignorance really our enemy, or are appetite, compulsion and ingrained habit the chief culprits? These aren't just idle questions but matters of immediate relevance in the war against obesity, the stakes of which were just raised. On the same day last week that Starbucks made its announcement, the American Medical Association voted to classify obesity as a disease. This means that in the eyes of the largest physicians" group in the United States, the roughly 90 million Americans who are formally considered obese - that's about 30 percent of the population - aren't just in imperfect health. They're downright ill, and we need to heal them. Calorie postings are one of public health officials" attempts to do that. The results so far aren't especially encouraging. Brian Elbel, a population-health expert at New York University's school of medicine, examined fast-food receipts from four chains in New York both before the city law went into effect and after, to see if customers were altering their orders to reduce the calories they consumed per visit to the restaurants. He found no meaningful difference, and his subsequent research in Philadelphia, which in 2010 implemented a mandate like New York's, echoes and bolsters that conclusion. "It's becoming increasingly clear that nothing big is happening for a large group of people," Elbel told me. Other evidence isn't quite so grim. New York City commissioned a broader survey than Elbel's, looking at thousands of receipts from 11 chains. At three of them - Au Bon Pain, KFC and McDonald's - there was proof of calorie reductions after the law. But at seven there wasn't, and at Subway, which was promoting footlong sandwiches for $5 during the post-law survey period, calorie consumption per visit actually increased. "The effect of calorie counts is beneficial," Thomas Farley, the city's health commissioner, said during a phone interview on Friday. But it's small and somewhat spotty and can be overwhelmed by the marketing of the restaurant. Yet another study, confined to Starbucks stores in New York, noted a 6 percent decrease in customers" intake of calories after the posting began. But it also suggested some vexing limitations to the impact of advertised calorie counts. "Calorie reductions were highest in high-income, high-education neighborhoods (where we believe obesity rates to be lower)," Phillip Leslie, one of the study's authors, said to me in an e-mail. On top of which, the Starbucks customers as an overall group were more affluent than the fast-food customers whose unchanged behavior Elbel evaluated. "It raises a very important concern," said Leslie, an economist at the University of California, Los Angeles. The people who tend to be most responsive to information may be those we least aim to target. BRYAN BOLLINGER, who also worked on that study, drew my attention to something else in it. For the most part, Starbucks customers ordering sugary, creamy coffee beverages kept on doing so, seemingly because they had already figured that the drinks were fattening and had made a flabby peace with that. But customers indeed adjusted their food orders upon realizing that a pastry could easily exceed 400 calories. They hadn't bargained on, or planned for, that. "What really matters is what your prior beliefs are," said Bollinger, who teaches marketing at New York University's Stern School of Business. What also matters is how much of a nudge you're given. Cheryl Healton, the dean of global public health at New York University, told me that education and information could be effective in influencing a discrete, relatively easy behavior, like persuading someone to get vaccinated. "But when it's habitual and even addictive behavior, you're in a whole new ballgame," she said. Healton, an authority on tobacco use in particular, noted that the principal reasons for the remarkable decrease in smoking in New York City and elsewhere over the last few decades weren't ominous commercials and warning labels. They were taxes and the bans on indoor smoking. People kicked the habit when it became onerous, in cost and convenience, not to. Farley, the health commissioner, agreed. "The structural things were more effective for smoking than the information was," he said. And that - not any itch to play nanny - is why he and Mayor Michael Bloomberg support such measures as new taxes on sodas, which may never happen, and a ban on sugary drinks over 16 ounces, which is in legal limbo. We should certainly continue to give posted calorie counts a whirl. Even a tiny impact is better than none. But we also need a more forceful kick in our amply cushioned rears. We're not as plump as we are because we've never had our eyes opened to the wages of a Whopper. We're this way because it's all too easy, in a pang of hunger and collapse of resolve, to turn a blind eye to the toll. I know whereof I speak. My neighborhood Lenny's does, too.