Socioeconomic position and the impact of increasing availability of lower energy meals vs. menu energy labelling on food choice: two randomized controlled trials in a virtual fast-food restaurant.

Background: Food consumed outside of the home is often high in energy and population level interventions that reduce energy intake of people from both lower and higher socioeconomic position (SEP) are needed. There is a lack of evidence on the effectiveness and SEP equity of structural-based (e.g. increasing availability of lower energy options) and information provision (e.g. menu energy labelling) interventions on food choice.
Methods: Across two online experiments, participants of lower and higher SEP made meal choices in a novel virtual fast-food restaurant. To be eligible to take part, participants were required to be UK residents, aged 18 or above, fluent in English, have access to a computer with an internet connection and have no dietary restrictions. Participants were randomized to one of four conditions in a 2 × 2 between-subjects design: menu energy labelling present vs. absent and increased availability of lower energy options (75% of menu options lower energy) vs. baseline availability (25% of menu options lower energy). Participants also completed measures of executive function and food choice motives.
Results: The analysis of pooled data from both studies (n = 1743) showed that increasing the availability of lower energy options resulted in participants ordering meals with significantly less energy on average (- 71 kcal, p <  0.001, partial η ²  = 0.024) and this effect was observed irrespective of participant SEP. Menu labelling had no significant effect on energy ordered (- 18 kcal, p = 0.116, partial η ²  = 0.001) in participants from both higher and lower SEP. Furthermore, we found no evidence that executive function or food choice motives moderated the effect of increasing lower energy menu options or energy labelling on total energy ordered.
Conclusions: In a virtual fast-food environment, energy labelling was ineffective in reducing total energy ordered for both higher and lower SEP participants. Increasing the availability of lower energy options had an equitable effect, reducing total energy ordered in participants from higher and lower SEP.
Trial Registration: Study protocols and analysis plans were pre-registered on the Open Science Framework (https://osf.io/ajcr6/).