This cross-sectional study examined how energy density (ED) in meals and snacks is associated with overall diet quality, BMI and waist circumference (WC). On the basis of the data from 7-d weighed dietary record, all eating occasions were divided into meals or snacks based on time (meals: 06.00-10.00, 12.00-15.00 and 18.00-21.00 hours; snacks: others) or contribution to energy intake (EI) (meals: ≥15; snacks: <15%) in 1451 British adults aged 19-64 years. Irrespective of the definition of meals and snacks, both meal ED and snack ED (kJ/g; calculated on the basis of solid food only) were inversely associated with overall diet quality assessed by the healthy diet indicator (regression coefficient (β)=-0·29 to -0·21 and -0·07 to -0·04, respectively) and Mediterranean diet score (β=-0·43 to -0·30 and -0·13 to -0·06, respectively) in both sexes (P≤0·002), although the associations were stronger for meal ED. After adjustment for potential confounders, in both men and women, meal ED based on EI contribution showed positive associations with BMI (β=0·34; 95% CI 0·06, 0·62 and β=0·31; 95% CI 0·01, 0·61, respectively) and WC (β=0·96; 95% CI 0·27, 1·66 and β=0·67; 95% CI 0·04, 1·30, respectively). In addition, meal ED based on time was positively associated with WC in men (β=0·59; 95% CI 0·07, 1·10) and snack ED based on time was positively associated with BMI in women (β=0·15; 95% CI 0·04, 0·27). In analyses in which only acceptable EI reporters were included, similar results were obtained. In conclusion, the findings suggest stronger associations of meal ED with overall diet quality, BMI and WC compared with snack ED.