Abstract
IMPORTANCE: Calorie labels for prepared (ie, ready-to-eat) foods are required in large chain food establishments in the US. Large evaluations in restaurants suggest small declines in purchases of prepared foods after labeling, but to the authors' knowledge, no studies have examined how this policy influences supermarket purchases. OBJECTIVE: To estimate changes in calories purchased from prepared foods and potential packaged substitutes compared with control foods after calorie labeling of prepared foods in supermarkets. DESIGN, SETTING, AND PARTICIPANTS: This controlled interrupted time series compared sales 2 years before labeling implementation (April 2015-April 2017) with sales 7 months after labeling implementation (May 2017-December 2017). Data from 173 supermarkets from a supermarket chain with locations in Maine, Massachusetts, New Hampshire, New York, and Vermont were analyzed from March 2020 to May 2022. INTERVENTION: Implementation of calorie labeling of prepared foods in April 2017. MAIN OUTCOMES AND MEASURES: Purchased items were classified as prepared foods, potential packaged substitutes for prepared foods, or all other (ie, control) foods. The primary outcome was mean weekly calories per transaction purchased from prepared foods, and the secondary outcome was mean weekly calories per transaction purchased from similar packaged items (for substitution analyses). Analyses of prepared and packaged foods were stratified by food category (bakery, entrées and sides, or deli meats and cheeses). RESULTS: Among the included 173 supermarkets, calorie labeling was associated with a mean 5.1% decrease (95% CI, -5.8% to -4.4%) in calories per transaction purchased from prepared bakery items and an 11.0% decrease (95% CI, -11.9% to -10.1%) from prepared deli items, adjusted for changes in control foods; no changes were observed for prepared entrées and sides (change = 0.3%; 95% CI, -2.5% to 3.0%). Labeling was also associated with decreased calories per transaction purchased from packaged bakery items (change = -3.9%; 95% CI, -4.3% to -3.6%), packaged entrées and sides (change = -1.2%; 95% CI, -1.4% to -0.9%), and packaged deli items (change = -2.1%; 95% CI, -2.4% to -1.7%). CONCLUSIONS AND RELEVANCE: In this longitudinal study of supermarkets, calorie labeling of prepared foods was associated with small to moderate decreases in calories purchased from prepared bakery and deli items without evidence of substitution to similar packaged foods.