A longitudinal study showed that placing a calorie label on supermarket ready-to-eat foods slightly helped shoppers reduce their ready-to-eat calories.
Among 173 supermarkets in the Northeast, calories from ready-made baked goods purchased per shopping trip decreased by an average of 5.1% (95% CI -5.8 to -4.4) after stores introduced calorie labels on products, Joshua Pettimar reported, ScD, from Harvard Medical. Harvard Pilgrim School and Institute of Health Care in Boston, and colleagues.
A greater reduction was observed among prepared food items, with new calorie labels resulting in an average 11% (95% CI -11.9 to -10.1) decrease in calories per treatment, as the group noted in JAMA Internal Medicine.
Although these reductions were significant, they were generally small, equivalent to about 10 fewer calories per transaction than prepared baked items, such as cakes and cookies, and about 18 calories less than prepared foods, such as meat and cheese. There were no changes in the average number of calories purchased between ready-made appetizers and sides at the supermarket after the calories appeared on the package.
The authors noted that shoppers did not compensate for this reduction in calories by purchasing more similarly packaged foods without the calorie labels.
Although the average decreases were small, Betimar’s group remained positive about these changes, noting that “these decreases could be meaningful at a population level due to the prevalence of calorie labels in retail settings, and the frequency with which people eat prepared foods.” and a growing market for ready-to-eat foods in the supermarket.
However, in accompanying commentMarion Nestle, Ph.D., Master of Public Health, of New York University wasn’t entirely convinced, calling these tiny reductions in purchased calories “barely enough to appear capable of affecting body weight.”
She also noted that these results were not surprising, as they are in line with previous studies on labeling in fast food restaurants.
“Such interventions may have significant effects in some people – I, for example, pay close attention to calorie labels – but their population-based benefit appears small,” she wrote.
Nestlé made it clear that two things are necessary for this type of anti-obesity policy intervention to be truly effective. First, people need to be aware of how many calories they need in a day, as well as how the calories in certain items relate to this total – information that “many are likely to have.” But on top of that, the shopper also needs to be “willing and able to deprive themselves of delicious and attractive food when they reach their total calorie needs” — something that can be much more difficult for the average consumer.
She concluded, “My interpretation of the current state of obesity prevention research is that any single policy intervention is unlikely to show anything but small improvements.”
For this analysis, Petimar and his team looked at single-chain supermarkets with locations in Maine, Massachusetts, New Hampshire, New York and Vermont. They compared sales during the previous two years of the chain’s implementation of calorie labels in the prepared foods division with sales 7 months after the change, representing 4,459,407,189 items purchased in all stores during the 2015 to 2017 study period. Few of these transactions are online or use the advantages of SNAP.
The analyzes for the holidays, including during the weeks of Thanksgiving to Christmas, Easter week, and the week of July 4th, have been adjusted to reduce potential remaining confusion.
This study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.
Petemar and co-authors report grants from the National Institutes of Health and the Center for Science in the Public Interest.
Nestlé has not made any disclosures.