Putting a calorie label on ready-to-eat foods at the grocery store helped shoppers only slightly to cut back on ready-to-eat calories, according to a longitudinal study.
Of the 173 grocery stores in the Northeast, calories from prepared bakery products purchased per store visit dropped an average of 5.1% (95% CI -5.8 to -4.4) after stores introduced calorie labels on products, Joshua Petimar reported. ScD, from Harvard Medical. School and Harvard Pilgrim Health Care Institute in Boston, and colleagues.
An even greater reduction was seen in prepared delicacies, with new calorie labels causing an average 11% (95% CI -11.9 to -10.1) decrease in calories per transaction, the group noted. JAMA Internal Medicine.
Although significant, these average reductions were generally small, amounting to about 10 fewer calories per transaction from prepared bakery products, such as muffins and donuts, and about 18 fewer calories from delicacies, such as meat and cheese. There were no changes in the mean calories purchased between prepared entrees and grocery store side dishes after calories were visible on the packaging.
Note that shoppers did not compensate for this reduction in calories by purchasing more similarly packaged foods without calorie labels, the authors noted.
While the average declines were small, Petimar’s group remained positive about these changes, noting that “these declines may be significant at the population level given the ubiquity of calorie labels in retail environments, the frequency with which people consume prepared foods, and the growing market for prepared foods from the supermarket.”
In an accompanying commentary, however, Marion Nestle, PhD, MPH, of New York University, was not so convinced, calling these small drops in calories purchased “barely enough to seem able to have any impact on body weight.”
She also noted that these findings weren’t much of a surprise, as they are consistent with previous studies of labeling in fast food restaurants.
“Such interventions can have big effects on some people — I pay close attention to calorie labels, for example — but their population benefit seems small,” she wrote.
It takes a few things for this kind of policy intervention to combat obesity to be really effective, Nestle explained. First, people need to be aware of how many calories they need in a day, as well as how the calories in specific items compare to that total — information that “many are likely to have,” she noted. But on top of that, the shopper must also be “willing and able to abstain from appealing, delicious food once he’s reached his total calorie requirement”—something that’s probably much more difficult for the average consumer.
“My interpretation of the current status of obesity prevention research is that it is unlikely that a single policy intervention will show anything but small improvements,” she concluded.
For this analysis, Petimar and team looked at single-chain supermarkets with locations in Maine, Massachusetts, New Hampshire, New York and Vermont. They compared sales during the 2 years before the chain implemented calorie labeling in the prepared foods section with sales 7 months after the change, representing 4,459,407,189 items purchased in all stores during the study period from 2015 to 2017. Few of these transactions took place online. or using SNAP benefits.
The analyzes were adjusted for holidays, including the weeks from Thanksgiving to Christmas, the week of Easter and the week of July 4, to reduce potential residual confusion.
This study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.
Petimar and co-authors reported grants from the National Institutes of Health and the Center for Science in the Public Interest.
Nestle reported no disclosures.