Register receipts and surveys were collected from a total of 7750 customers in spring 2007 and from 8730 customers in spring 2009 at 168 fast food chain locations during lunchtime hours (at the two coffee chains, 4038 receipts and surveys were collected in 2007 and 3981 in 2009). Data were excluded if the purchase was for more than one person, if the customer’s order could not be identified, or if calorie information for any menu item could not be determined. The final study sample for the 11 lunchtime chains included 7309 customers for 2007 and 8489 for 2009. Overall, more than 80% of all customers were approached; the response rate for these customers was 60%. In 2007 only the Subway sandwich chain provided calorie information for a small number of items, for which they made health claims. In 2009, all chains included in this study were largely in compliance with the new regulation. Non-compliance was limited to variations in font sizes or background colours; in some cases, chains did not clearly post calorie information on in-store promotional materials.
Table 1 presents the sample distribution for 2007 and 2009 by fast food chain, customer demographics, and descriptive statistics for the purchases. This table also shows the percentage of customers who reported using the calorie information. McDonald’s and Subway each account for a quarter of all restaurants in the study and together account for 58% of all receipts collected. Conversely, the three pizza chains together account for 12% of the restaurants included, while their customers account for only 4% of receipts collected. The sample distributions by fast food chain were similar for the two time periods. In both periods women made up about half of the sample, and a third of receipts came from stores in high poverty neighbourhoods. Purchasing patterns were similar in the two time periods; however, slightly fewer customers purchased a beverage in 2009 (54%, compared with 58% in 2007, P<0.001). The average cost across all purchases, adjusted for inflation, increased by 42 cents.
Table 1 Details of lunchtime purchases from fast food outlets in New York City: stores and customers in samples for 2007 and 2009 and customers seeing and using calorie information in 2009. Values are numbers (percentages) unless stated otherwise
Overall, 15% of customers reported using the calorie information when deciding on their purchase for that day. This was higher at the two sandwich chains, Subway and Au Bon Pain, where over 20% of customers reported using the posted calorie information (table 1). Women were more likely to report using calorie information (18% v 13% of men, P<0.001), as were customers in stores in the wealthiest neighbourhoods (19% v 17% in neighbourhoods with moderate poverty and 12% in stores in the poorest neighbourhoods; p<0.001). This pattern was similar by neighbourhood of residence. The youngest customers (18–24 year olds) were the least likely to report using calorie information (11% v 16% of older customers, P<0.001). Customers who reported using calorie information also purchased fewer food items on average (1.77 v 2.03, P<0.001), and fewer purchased a beverage (51% v 54%, P=0.03). There was no difference in purchase price between customers who reported using calorie information and those who did not ($5.19 v $5.07, P=0. 07).
At lunch locations, unadjusted pre-regulation mean energy content per purchase ranged from a low of 555 kcal at Au Bon Pain to a high of 1309 kcal at Pizza Hut. At hamburger chains, the means were within 100 kcal across the three chains, with a low of 829 at McDonald’s and a high of 924 at Burger King. Mean energy at the two chicken fast food chains were similar (927 kcal at KFC and 949 at Popeye’s), while mean energy content per purchase across the three pizza chains was more varied. The post-regulation data show similar trends between chains (table 2).
Table 2 Change in mean energy content of lunchtime purchases from fast food outlets between 2007 and 2009, before and after introduction of calorie labelling
After regulation, three major chains with large sample sizes showed statistically significant reductions in mean energy content per purchase: a 44 kcal reduction at McDonald’s (829 v 786, P<0.02), 80 kcal reduction at Au Bon Pain (555 v 475, P<0.001), and 59 kcal reduction at KFC (927 v 868, P<0.001). Together, these three chains represent 42% of all customers in our study. One chain, Subway, showed a significant increase in mean energy content per purchase (749 v 882 kcal, P<0.001). Overall, combining unadjusted data from the 11 fast food chains, there was no significant change in mean calories per purchase from before to after regulation (828 v 846 kcal, P=0.22) (table 2).
Customers who reported using the calorie information after regulation purchased 106 fewer calories, on average, compared with customers who didn’t see or didn’t use the information. This difference was highest at hamburger chains, where customers who reported using calorie information reduced the mean energy content of their purchases by >130 kcal compared with other customers. The reduction was significant at six chains and overall (P<0.001). This pattern held for both men and women, for all age groups, and across neighbourhoods (table 3).
Table 3 Difference in mean energy content of lunchtime purchases from fast food outlets in 2009 between customers who reported using information on calorie labelling and those who did not
In order to control for some of this variability between chains and changes in the composition of the sample from 2007 to 2009, we used linear regression models to estimate kilocalories per purchase. Table 1 provides the descriptive statistics for the variables included in these multivariate models, and tables 4 and 5 present the results of the regression analyses.
Table 4 Results of linear regression analyses for mean energy content (kcal) of lunchtime fast food purchases in 2007 and 2009, before and after introduction of calorie labelling
Table 5 Results of linear regression analyses for mean energy content (kcal) of lunchtime fast food purchases in 2009, by customers’ use of information on calorie labelling Difference in mean energy content of purchase before and after regulation
Model 1 estimates change in mean energy for all purchases from before to after regulation, adjusting for restaurant chain, poverty level for the store location, and sex of customers (table 4). The results of this model are similar to the crude estimates in table 2, with a non-significant 15 kcal increase after regulation. Model 2—which adds adjustments for the type of purchase, including number of food items, whether a beverage was purchased, and inflation adjusted cost—produces a decrease of 20 kcal in mean energy content per lunchtime purchase, from 847 kcal in 2007 to 827 kcal in 2009 (P=0.01) (table 4).
Difference in mean energy content of purchase by use of calorie information
The two models presented in table 5 compare energy content per purchase between customers who reported using the calorie information in 2009 with all other customers in 2009. After adjustment for restaurant chain, neighbourhood poverty, age, and sex, the customers who reported using calorie information purchased an average of 96 fewer kilocalories compared with customers who didn’t use the information (model 1). After further adjustment for purchase type, including number of items, beverage purchase, and cost, customers who reported using calorie information purchased 78 fewer kilocalories than those who did not (782 v 859 kcal, P<0.001).