For decades, weight control experts have emphasized personal responsibility. The idea is that people need to choose to eat less (and presumably move more). There is considerable controversy over this energy balance theory. Diet composition and timing might both play a role in weight gain. Some hypotheses also credit intestinal microbes. But no one disputes that people have a hard time choosing foods with less energy when they don’t have calorie information at the point of purchase.
Impact of Calorie Information in Supermarkets:
Do labels providing nutrition information including calories affect purchasing habits? One recent study compared purchases before and after calorie-labeling was instituted (JAMA Internal Medicine, August 1, 2022).
The researchers analyzed sales data for 173 stores in a supermarket chain serving New England and New York. The items sold between April 2015 and April 2017 captured consumer behavior before the labeling change went into effect. Further, they compared these sales to items sold between May and December 2017. That period was just after the chain added nutrition labels with calorie information to prepared foods. The analysis included more than 3 billion items.
In general, prepared foods may be less healthful than homemade foods, as they may have more saturated fat, salt and calories. That is why policy makers have been anxious to label prepared foods clearly so consumers would know what they are purchasing.
Did the Nutrition Labels Make a Difference?
After excluding prepared produce such as sliced fruit and whole prepared seafood (such as lobster–New England supermarkets carry it), the investigators calculated calories purchased per week in the categories of bakery, deli and entrées or sides. For the purpose of comparison, they used produce, meats, milk and certain other foods as controls.
After nutrition labels started providing calorie information, people cut their calories from bakery purchases by about 5 percent. Deli items purchased had an average 11 percent fewer calories after the labeling change. The researchers report no significant reduction in calories from prepared entrées or side dishes.
As a result, they estimate
“On the absolute scale, these results approximately translate to a 10–calorie-per-transaction decrease for prepared bakery items, no change for prepared entrées and sides, and an 18–calorie-per-transaction decrease for prepared deli items.”
In the discussion, the scientists observe that such small changes for an individual purchase might add up over time, when you take the number of grocery shoppers into account. They express the hope that providing calorie information could help reduce obesity and also benefit cardiovascular health.
The authors conclude
“Findings from this longitudinal study indicate that calorie labeling in a supermarket chain was associated with small to moderate decreases in calories purchased from prepared bakery and deli items 7 months after labeling implementation. These declines may lead to population-level health benefits if they translate to similar changes in consumption.”