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

	Model 1*			Model 2*
	Mean (95% CI) energy content/purchase (kcal)	P value		Mean (95% CI) energy content/purchase (kcal)	P value
Estimated marginal means
2007	829.3 (813.6 to 845.0)	—		847.5 (837.2 to 857.8)	—
2009	844.6 (831.6 to 857.6)	—		827.3 (817.8 to 836.8)	—
Parameter estimates
2007	Reference	—		Reference	—
2009	15.3 (34.5 to −3.8)	0.12		−20.2 (−4.5 to −35.9)	0.01
Sex (women–men)	−111.4 (−125.6 to −97.2)	<0.001		−52.5 (−60.0 to −45.0)	<0.001
Poverty level of store location†	−6.3 (−65.3 to 52.8)	<0.001		36.5 (0.3 to 72.7)	0.05
Description of purchase:
No of food items	—	—		155.0 (139.6 to 170.3)	<0.001
Beverage (0=No; 1=Yes)	—	—		33.7 (20.6 to 46.9)	<0.001
Cost (inflation adjusted)	—	—		104.8 (98.7 to 110.9)	<0.001

*Model 1 adjusted for restaurant chain, sex, and neighbourhood poverty. Model 2 further controlled for the number of food items purchased, beverage purchased, and cost. Both models included a variable for chain, to adjust for change in customer volume across the two years.

†Poverty is a continuous variable defined as the percentage of households in the store’s zip code that were below twice the national poverty level.