Examining the interaction of fast-food outlet exposure and income on diet and obesity: evidence from 51,361 UK Biobank participants

Table 3 Associations of household income with body mass index (estimated using a multivariable linear regression model, n = 51,361), obesity (estimated using a binomial logistic regression model, n = 51,361), and frequent consumption of processed meat (estimated using a binomial logistic regression model, n = 51,090) in the Greater London UK Biobank sample

	Household Income (£/year)	Model 1^a		Model 2^b		Model 3^c		Model 4^d
	Household Income (£/year)	β	95% CI	β	95% CI	β	95% CI	β	95% CI
Difference in BMI (kg/m²)	> 100,000	ref		ref		ref		ref
	52,000–100,000	0.71**	0.55, 0.87	0.60**	0.45, 0.76	0.44**	0.29, 0.60	0.33**	0.17, 0.48
	31,000–51,999	1.17**	1.01, 1.33	0.95**	0.80, 1.11	0.67**	0.51, 0.83	0.51**	0.35, 0.67
	< 31,000	1.73**	1.58, 1.88	1.36**	1.21, 1.51	0.85**	0.69, 1.01	0.68**	0.52, 0.84
		Model 1^a		Model 2^b		Model 3^c		Model 4^d
		OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Odds of obesity (BMI ≥ 30 kg/m²)	> 100,000	ref		ref		ref		ref
	52,000–100,000	1.42**	1.29, 1.56	1.37**	1.24, 1.50	1.29**	1.17, 1.41	1.22**	1.11, 1.34
	31,000–51,999	1.70**	1.55, 1.86	1.57**	1.43, 1.72	1.41**	1.28, 1.54	1.32**	1.20, 1.45
	< 31,000	2.29**	2.10, 2.49	2.02**	1.84, 2.20	1.66**	1.51, 1.82	1.54**	1.41, 1.69
		Model 1^a		Model 2^e		Model 3^c		Model 4^d
		OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Odds of frequent consumption of processed meat^f (> once per week)	> 100,000	ref		ref		ref		ref
	52,000–100,000	1.08*	1.00, 1.16	1.17**	1.09, 1.27	1.13*	1.05, 1.22	1.10*	1.02, 1.19
	31,000–51,999	1.01	0.94, 1.09	1.24**	1.15, 1.34	1.19**	1.10, 1.29	1.14*	1.06, 1.24
	< 31,000	1.01	0.94, 1.08	1.38**	1.28, 1.49	1.30**	1.20, 1.41	1.25**	1.15, 1.35

Measure of interaction (fast-food exposure*household income with difference in BMI) on a multiplicative scale based on an F-test, P = 0.230 | *p < 0.05; ** p < 0.001 | ^a Model 1 adjusts for number in household | ^b Model 2 additionally adjusts for age, sex, ethnicity, smoking status | ^c Model 3 additionally adjusts for highest educational attainment and UK Biobank assessment centre attended | ^d Model 4 additionally adjusts for fast-food outlet proportion and the sum of counts of Supermarkets, Restaurants, Convenience stores, Cafes and Specialist Stores within 1 mile Euclidean (straight line) radius buffers of home address | ^e Model 2 adjusts for age, sex, ethnicity | ^f Includes bacon, ham, sausages, meat pies, kebabs, burgers, chicken nuggets