Sustainable diets are patterns that change consumer behaviour towards more balanced and plant-based habits. This study investigates the effect of individuals’ predisposition to adopt sustainable diets while reducing meat intake by measuring their psychological proximity to meat. Using an online consumer-based platform, a cross-sectional survey collected responses from 497 individuals. Questionnaire items included 43 questions prospected from the literature, coded as practical and essential barriers and measured on a modified 7-point Likert scale. The results showed some paradoxes, as a high predisposition to adopt a sustainable diet coexists with a high predisposition to consume animal-based proteins. The main perceived barrier to adopting a plant-based diet was the enjoyment of eating meat, followed by the lack of information about plant-based diets. Barriers related to meat alternatives remained the highest above all the others. It confirms that, for local consumers, meat remains a usual option and is easier to prepare. When investigating the moderating effect of barriers on the predisposition to behaviours towards meat intake reduction, no effect was confirmed. However, we found a U-shaped moderating effect for plant-based meal increase, confirming the psychological proximity of the meat consumption effects under the lens of the Construal Level Theory and Transtheoretical Model. These findings call for further research on the effectiveness of measuring psychological barriers related to sustainable diet adoption.