Interventions
This study was conducted using ‘Take a BITe’, a simulated food delivery platform created and hosted by the Behavioural Insights Team. The platform has a similar design to real-world food delivery platforms such as Deliveroo, UberEats, and JustEat. There were 21 restaurants and 570 food or drink items, each in three different portions (i.e. 1710 individual food options in total). Data were used from research on the nutritional content of takeaway food options [
Screenshots of the 'Take a BITe’ online platform, showing (The five study conditions (shown illustratively in Fig. 
Control (C): restaurants and foods positioned in a random order. Food items were randomly ordered within food categories, but the order in which food categories appear was not randomised (e.g. starters presented first, followed by mains, etc.).Foods only (F): all food items listed in ascending order of energy content within each restaurant and food category (e.g. starters, mains), with restaurants ordered at random.Restaurants only (R): restaurants listed in ascending order of average energy content per main meal, with foods listed at random within restaurant menus.Foods and restaurants (FR): a combination of interventions 1 and 2, where foods were listed in ascending order of energy content in menus and restaurants were listed in ascending order of average energy content per main meal.Foods and restaurants plus price (FRP): restaurants and foods were repositioned as in intervention 3, but this time using a kcal-price index. For the restaurant order, the index was calculated by dividing the average energy content of mains by the average price of mains for each restaurant. For the food order within food categories of restaurant menus, the index was calculated by dividing the energy of a dish by the price. This meant that lower energy but higher price options were positioned at the top. The FRP trial arm primarily sought to test for proof-of-concept if positioning based on consideration for both health and profits, with price here used as a proxy for profits, could impact energy purchased while remaining sensitive to financial constraints of industry.
Illustrative concept diagrams of the study conditions showing (