No intervention:

Default proportion condition (33% lower energy density items - 67% higher energy density items). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category.

No labelling.

When energy density of a food item ≤ median of energy density distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions will introduce the badges to the participants as "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."

The proportion of lower energy density items vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (33% lower - 67% higher). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category.

The proportion of lower energy density items vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (33% lower - 67% higher). Lower energy density items will be defined as lower ED ≤ median of ED distribution within a food category.

When energy density of a food item ≤ median of energy density distribution within a food category, "healthier choice" badges will be added to the food item pictures on the online supermarket. Instructions will introduce the badges to the participants as "In the online supermarket, the green tick allows you to see which products (e.g. muesli) in each product category (e.g. cereals) are healthier choices with fewer calories per gram than most other products in the same category."

The proportion of lower energy density vs. higher energy density items will be reversed (67% lower - 33% higher) relative to the default proportion condition (D and DL) (33% lower - 67% higher). Lower energy density items will be defined as lower energy density ≤ median of energy density distribution within a food category.

Calculated as the sum of the energy of the purchased items (kcal) divided by the sum of their weight (g) and multiplied by 100.

Calculated as the sum of the energy of the purchased items (kcal)

Mean of item "I would normally buy [the 10 items on the shopping list]" for all the food items coded as: 1 = Never; 2 = Very rarely; 3 = Rarely; 4 = Occasionally; 5 = Frequently; 6 = Very frequently.