Results
The study was run from February to March 2022. 15,051 entrants were assessed for eligibility to participate. 5,148 were excluded for failing to meet inclusion criteria or failing attention checks. 9,293 completed the study task, but 290 were excluded from analysis because their hypothetical order baskets contained either more than 4,000 or fewer than 150 kcals (see CONSORT Flow Diagram, Fig. 
1819 in the control group,1858 in the foods only repositioning intervention (F),1812 in the restaurants only repositioning intervention (R),1749 in the foods and restaurants repositioning intervention (FR), and.1765 in the foods and restaurants repositioning based on energy content and price (FRP).
CONSORT flow diagramAcross all conditions, participants ordered on average 1269 kcal with a value of £14.63 (see Supplementary Tables Compared to the control, repositioning both foods and restaurants purely based on the energy content of options resulted in the greatest effect (-209 kcal; 95% CIs: -248, -168), followed by repositioning restaurants (-161 kcal; 95% CIs: -201, -121), repositioning restaurants and foods based on a kcal/price index (-117kcals; 95% CI: -158, -74) and repositioning foods based on their energy content (-88kcals; 95% CI: -130, -45) (Fig. 
Mean energy from foods selected in the control group and the four intervention groups (foods repositioning, restaurants repositioning, and foods and restaurants repositioning, foods and restaurants plus price repositioning). Bar ranges represent 95% confidence interval, and ** indicates adjusted p < 0.01In a comparison of estimated marginal means for total energy in participants’ baskets, all interventions led to baskets with significantly lower energy contents than the control. All intervention groups significantly differed from each other in terms of their effect on the energy content of participants baskets, with the exception of interventions F (foods repositioning) and FRP (foods and restaurant plus price repositioning), which did not significantly differ (Table 
Estimated percentage change between all study groups for total energy from foods selected. The reference group is the first group listed*Confidence intervals are calculated using HC3 heteroscedasticity-robust standard errorsThe average energy content of mains and the energy density of a standardised serving was also lower in all interventions when compared to the control (Supplementary Tables The total basket price at checkout varied between interventions. All interventions repositioning options purely based on the energy content of items reduced the basket price at checkout. However, the interventions that repositioned options to give more prominence to lower-energy but higher-price foods and restaurants (FRP) reduced the energy content of participants’ baskets whilst increasing the basket price (Fig. 
Mean money spent (£) in the control and four intervention groups. Bar ranges represent 95% confidence interval, and ** indicates adjusted p < 0.01Subgroup analysis found there was a greater impact among people of higher versus medium SEP of the FRP intervention (147 fewer kcal ordered, 95% CI: 53–241, p-value: 0.022) (Fig. 
Marginal mean plots for average energy (in kcals) placed in basket by (The study task could be undertaken from a desktop or mobile device. There was a greater impact of the intervention among people using a mobile device compared to desktop in the study conditions that involved repositioning restaurants purely based on energy content (199 fewer kcal ordered, p-value: 0.003 for study arm R;139 fewer kcal ordered, p-value: 0.046 for study arm FR) (Fig. There was a greater intervention effect among participants that used a delivery platform more than once a week compared to those that used it less than once a week for the intervention repositioning restaurants based on the energy content of their mains (133 fewer kcal selected, p-value: 0.021 for study group R) (Fig. All other subgroup analyses and interactions tested were not significant.