About this trial
Calorie labelling in out-of-home (OOH) settings was introduced by the government in England as part of a wider strategy to 'tackle obesity' (DHSC, 2020). The OOH sector encompasses outlets where food and drinks are prepared for immediate consumption, on or off the premises (DHSC, 2021). Increased consumption of OOH food is associated with greater intake of energy and nutrients of concern; therefore, is implicated in poorer dietary quality and ill-health (Gesteiro et al., 2022). The key ambition for the calorie labelling policy was to inform consumers of the calorie content of their food choices, making it easier to select healthier food choices (DHSC, 2020). An additional potential benefit of the policy was to prompt reformulation by the food industry to either reduce the calorie content of foods on offer or provide new lower calorie options (DHSC, 2021).
The calorie labelling policy in England was criticised at the time of implementation in the media for its potential to cause harm in individuals with eating disorders (Polden et al., 2023). However, limited research had explored effects on individuals with eating disorders (Robinson et al., 2023). It is estimated that over a million individuals in the UK are living with an eating disorder (Beat Eating disorders, 2026). Therefore, it is important for research to understand the impact of food labelling interventions on mental health outcomes in individuals with eating disorders and other mental health conditions, and whether alternative nutritional labelling practices that are not focused on calories alone could have positive health impacts without unintended negative consequences.
One alternative form of nutritional labelling that could be considered in OOH settings is Nutri-score. Nutri-score provides food items with a label from A (dark green, healthiest) to E (Red, least healthy) according to the content of both positive (e.g. fibre, protein) and negative (e.g. saturated fat, salt, sugar) nutrients. Nutri-score has been implemented as a front-of-pack label in several countries across Europe, with positive impacts on the healthiness of food purchasing in supermarkets (Andreani et al., 2025). Two studies have assessed Nutri-score in OOH settings, also finding associations between Nutri-score and healthier food choices (Chandon \& Indaburu, 2026; Julia et al., 2021). However, Nutri-score on food menus has not previously been examined in terms of the potential impact on individuals with eating disorders and other mental health outcomes.
Nutri-score encompasses the nutritional quality of a food product, by accounting for both positive and negative components. This may be less harmful to individuals with eating disorders as it would remove the focus on calorie content. Previous qualitative research has shown that individuals with eating disorders may support labelling strategies that provide more holistic approaches to nutrition (Trompeter et al., 2026). It could also be of benefit to general population health to focus on helping individuals to consume a well-rounded diet higher in positive nutrients (fibre, protein), with high fruit, vegetable and nut content, and lower in negative nutrients that contribute to ill health (salt, sugar, fats). To date, limited research has compared Calorie labelling to Nutri-score in the general population or among those living with mental health conditions, like eating disorders.
OBJECTIVES This new study will explore the impact of Nutri-score labelling vs Calorie labelling vs no labelling (Control) in a simulated OOH food delivery ordering platform (common setting for food purchasing and calorie labelling is required by law in England) on participants' perceived effectiveness of nutritional labelling, healthiness of food choices, positive and negative affect, and perceived impacts on mental health.
We will examine effects in a general population sample (no eating disorder diagnosis), a sample of participants with a past or current diagnosis of an eating disorder by a medical practitioner and a sample of participants with a common mental health condition diagnosed by a medical practitioner without eating disorder (e.g., anxiety), in order to understand potential effects across groups of participants who may differ in their risk of poorer mental health in response to nutritional labelling.
(references in attached protocol)
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Residing in the UK
Regularly eat food prepared out of the home (from restaurants, cafes, fast food etc., at least once a month)
Over the age of 18 years
Fluent English speaker
Disqualifiers
Pregnant/breastfeeding
Have taken part in a previous study using the same version of the online food choice task (exclusion list obtained from prolific)
Trial design
Parallel
Treatments tested in this trial
Control condition
BehavioralParticipants will be asked to select a meal from a food menu with no nutritional labelling
Calorie labelling
BehavioralParticipants will be asked to select a meal from a food menu with calorie labelling
Nutri-Score labelling
BehavioralParticipants will be asked to select a meal from a food menu with calorie labelling
Treatment groups
Trial outcomes
Primary outcomes
Perceived Message Effectiveness
An adapted version of the University of North Carolina Perceived Message Effectiveness (PME) scale will be used as a measurement of how effective participants believe nutritional labelling is in promoting behaviour change. The scale measures health concern, product attitude, and discouragement of item consumption in response to public health messaging or in this context, the food menu presented during the study. Participants will be shown a screenshot of the menu they ordered. All participants will answer 3 questions using a Likert scale ranging from 1 - 5 anchored by "Strongly disagree" and "Strongly agree". The mean response to the three items will be calculated. PME is used as an early indicator of a health messages potential to change behaviour (e.g., reduce selection of less healthy items). The scale has been used previously to identify the potential impact of food labels and is predictive of long-term behaviour.
Perceived usefulness of menu in identifying healthier/less healthy food choices
Participants will be asked 'To what extent was the menu useful in helping you identify healthy vs. less healthy food choices'. Participants will select their answer on a Likert scale ranging from 1 - 5 anchored by "Strongly disagree" and "Strongly agree".
Nutritional quality of food ordered
An overall measure of nutritional quality of participants food order will be calculated using mean UK NPM scores of individual items, weighted according to the energy content of the item. Nutritional content used to calculate NPM scores for each menu item was obtained from outlet websites and input into the online NPM calculation tool (2004/05). Weighted scores will be calculated using the weighted.mean function in R.
Positive/negative affect
Participants will complete an adapted version of PANAS after completing the food selection task. This is a 20-item measure, whereby participants will be asked to 'indicate the extent you feel this way right now' on a scale of 1 to 5 from 'very slightly or not at all' to 'extremely'. Participants receive a positive affect score and a negative affect score.
Secondary outcomes
Nutri-Score labels of selected food items
We will record the Nutri-Score values (A-E) of all items selected by participants in the food choice task. Participants will be coded as having ordered any of the healthiest menu items labelled A or B (Y/N) and/or the least healthy menu items labelled D or E (Y/N).
Energy content of meals
We will record the energy and nutrient content of all items selected by participants in the food choice task. The total energy content of the ordered meal will be calculated.
Other outcomes
Participant education
Participants will be asked to report their highest level of education achieved: * Less than high school * High school completion * College or foundation degree * Bachelor's degree * Master's degree
Notice and impact of labels
Participants will be asked several questions to assess whether they noticed any nutritional labelling, and if the labelling impacted their food choices. Questions will be amended slightly according to labelling condition.
Participant age
Participants will report their age on a dropdown list
Participant gender
Participants will select their gender from the following options: * Man * Woman * Non-binary * Other * Prefer not to say
Sponsors and contacts
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University of Liverpool
Lead sponsor
King's College London
Collaborator
University of Oxford
Collaborator
Liverpool John Moores University
Collaborator
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