High-meat consumption negatively impacts our planet and our health, especially in high-income countries where this eating pattern is the norm. Shifting peoples’ eating patterns to align with a plant-rich diet is now considered crucial to reduce greenhouse gas emissions generated from agricultural production and improve human health and animal welfare. This thesis presents research that aims to: (1) explore which plant-rich diet to promote to Australian adults; (2) understand the barriers and drivers to the target plant-rich diet; and (3) develop and test an intervention to increase uptake of the target plant-rich diet, based on the barriers and drivers identified in the previous study.
In the first study, we assessed a range of plant-rich diets (Mediterranean, flexitarian/semi-vegetarian, pescatarian, vegetarian, and vegan) using the community-based social marketing framework (CBSM) (McKenzie-Mohr, 2011). Each diet was assessed using three metrics, the first relating to the environmental, human health, and animal welfare impact of each plant-rich diet, with the second and third metrics being self-reported data (N = 253 Australian adults) on current adoption and willingness to adopt each of these diets, respectively. Following the CBSM calculation for impact, the Mediterranean diet was identified as the target plant-rich diet, as it had the greatest projected positive impact score.
Using a combination of different research methodologies, the next two studies assessed the barriers and drivers to Mediterranean diet adoption using the capability-opportunity-motivation model of behaviour (COM-B) of the behaviour change wheel (BCW) (Michie et al., 2011). The first study was a qualitative study whereby 16 Australian adults who ate an omnivore or plant-rich diet were interviewed. Inductive and deductive analyses were applied using reflexive thematic analysis (Braun & Clarke, 2019; Braun et al., 2022) and the COM-B, respectively. Key barriers identified were: 1) changing ingrained meat habits; 2) lack of physical and mental availability; 3) household influences; 4) meat perceived as tasty and Mediterranean diet foods as bland; and 5) minimal knowledge of the nutritional benefits of Mediterranean diet foods.
The next study was a quantitative study. Informed by the qualitative study results, an online sample of 443 Australian adults was surveyed to assess predictors of Mediterranean diet adoption. Exploratory factor analysis revealed four main factors (Lack of Time and Knowledge, Food Allergies and Clean Eating, Meat Dependence, and Household Dietary Preferences), that together with Mediterranean Diet Familiarity and Not Having to Cook for Others, predicted 44% of the variability in Mediterranean diet adoption. Assessing existing eating behaviours also highlighted that omnivores, on average, ate red meat more often, and legumes less often, than their meat-reducing counterparts.
The final study involved the development and evaluation of 11 legume-focused message attributes to increase legume consumption intentions within a sample of 201 Australian residents. Multilevel modelling revealed that message attributes referencing taste and convenience significantly increased intentions to consume legumes. In contrast, for high meat eaters, message attributes promoting enablement strategies or referring to health and financial benefits significantly decreased (and may be detrimental to) legume consumption intentions.
Overall, it can be concluded that shifting people from eating a high-meat diet to eating the Mediterranean diet requires a multifaceted approach that encompasses one’s capability, opportunity, and motivation. Creating greater systemic opportunities for sustainable eating environments also needs to be considered in addition to promoting individual behaviour change.