The feasibility and acceptability of using physical activity calorie equivalent (PACE) labelling on social media to improve health behaviours

Excess energy intake through discretionary food consumption contributes to obesity. There is limited evidence that current food labelling strategies are improving eating behaviours.

Physical activity calorie equivalent (PACE) labelling is a novel approach to food labelling that aims to provide the public with information about the amount of physical activity needed to expend the number of kilocalories (kcal) in food and drinks. PACE labelling may help the public to better understand what kcals represent and therefore make healthier food choices.

Social media is an influential and economical platform for health communication that may have large-scale impact on the behaviours of the public. To date, no health intervention has used social media as a tool to disseminate PACE information, specifically to impact health outcomes. In this thesis, I address this gap by investigating the feasibility and acceptability of using discretionary food PACE labelling on social media in healthy adults. This thesis contains three related studies. Using a theoretical behaviour change framework and theory, I developed a three-month PACE social media intervention (Food shOppers' sOcial meDia Study (FOODS)) which included extensive feedback from members of the public. I then investigated both quantitatively and qualitatively if the FOODS intervention was acceptable and feasible to participants, and whether it showed promise of improving health behaviours.

Results from a randomised controlled trial (RCT), where 103 participants were randomised to the FOODS PACE intervention or a kcal-only comparator in seven months, indicated that the recruitment rate was feasible, albeit with modifications to the recruitment strategy to make it less time intensive. The retention rate was high with 85/103 participants (82.5%) completing all measures at follow-up. The proportion of participants who maintained intervention engagement by keeping social media notifications turned on for the duration of the intervention (three months) was 77/85 participants (90.6%) at follow-up, indicating that the intervention was acceptable to participants. Both trial groups reduced their discretionary food intake by approximately 200 kcal/day, lost a small amount of weight with a reduction of 1.1 kg and 0.6 kg in the in the intervention and comparator groups respectively, and increased their total physical activity levels by 24 minutes/week (intervention) and 53 minutes/week (comparator). The nested qualitative study showed that participants believed PACE information delivered via social media was useful for translating the meaning of kcals and energy balance and it helped them to reduce their discretionary food intake.

Following the intervention development phase of this research, the results from the RCT and qualitative study indicate that it is feasible to deliver a PACE labelling intervention using social media and that the public are willing to participate in such an intervention. These findings have important implications for public health research, practice, and policy because the intervention could provide a cost-effective and scalable way of contributing to reducing the obesity epidemic, specifically by reducing excess energy intake from discretionary food.