Mayor Michael Bloomberg's touting a new Stanford Business School study that suggests Starbucks customers have been easing back on the indulgences since the city’s calorie-posting law took effect in 2008. The study hasn't been published yet, but is in the process of being peer reviewed for 'a leading economics journal,' co-author Phillip Leslie told WNYC.
There have been a number of recent studies on whether posting calories affects consumer decisions, but Leslie says this is the first one to use a company’s internal data. He and his co-authors looked at a dataset of more than 100 million transactions at every Starbucks in New York City (222 of them) over 14 months, and at the buying habits of 7,500 anonymous Starbucks cardholders. They found a six percent drop in calories consumed, most of it in food. They found the levels stayed down 10 months after calories first went up on menu boards next to prices.
At Starbucks in wealthier neighborhoods, the drop was even sharper – with the well-heeled drinking and eating 26 percent less fattening food. The authors note that Starbucks is just one chain attracting a particular slice of society, and they don't think the results necessarily say anything about food purchasing habits city-wide.
They have no intention of doing a similar study on other chains, which have generally been more secretive with their figures. One study last year in the journal Health Affairs found calorie postings don’t seem to be having an effect in poor neighborhoods with high diabetes rates. But another study, conducted by the city Health Department, found a slight decline among consumers at many, though not all, fast food chains.