The definition of sustainable diet varies between the authors and countries (1). However, the main characteristics are provided by Lonnie et al. (2) : to consume a variety of unprocessed or minimally processed foods, (i.e., whole-grains, pulses, fruits and vegetables), with moderate amounts of eggs, dairy, poultry and fish and modest amounts of ruminant meat . The Food and Agriculture Organization has published a more broad definition of sustainable diet: ‘Sustainable diets are protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable; nutritionally adequate, safe and healthy; while optimizing natural and human resources’ (3).

As you can imagine, it is particularly challenging to operationalize the sustainable diet behaviors for future interventions. A behavioral intervention could target the adopting plant-based diet, decrease the consumption of meats, sugar added product, ultra-processed food, soda, dairy products (particularly cheese)…. The behavioral change perspectives of sustainable diet are in line with debates about multiple health behavior change interventions (i.e., sequential versus simultaneous approach, number and order of targeted behaviors, rebound effects…) (4–6).

I tried to identify the systematic reviews examining the effects of ‘real-context’ behavioral interventions to help adults to adopt more sustainable diet behaviors. No surprise ! Most of published papers focused on animal-based diet or adoption of plant-based diets. It is easily understandable because the meat consumption reduction is particularly interesting in term of individual carbon footprint reduction (7,8) and is associated with various health benefits. Furthermore, the reduction of red and processed meat is also associated with a decrease of water and ecological individual footprints (9).

Five reviews and one report was found (10–15). I also added two narrative reviews of the special issue of Current Opinion in Behavioral Sciences about climate change (16,17). The number of interventions was relatively low and their respective efficacy is disputable. Most of interventions were performed in a ‘controllable’ context (e.g., cafeteria).

What are the psychological targets (and possible behavioral change techniques) to develop a future effective behavior change intervention ?

• Health beliefs (to provide the information about health benefits or consequences) (10,11,14)
• Food knowledge (to develop the skills and abilities preparation of new food or plant-based meals) (10,11,14)
• Environmental beliefs (to provide the information about environmental benefits or consequences) (14,15)
• Self-regulation (to facilitate action planning, to prompt self-recording) (11,14)

What are the most recurrent psychological barriers ?

• Positive taste experiences with meat (10,12)
• Health risks perception associated with a diet without meat (10,12)
• Food preparation or purchase habits (10,10,13)
• Poor social support or unwillingness of household members (10,13)

It is important to note that the findings are only generalizable in adults living in countries with high-incomes. Also, higher incomes and levels of education were associated with easier shift from meat- to plant-based diets (11,13).

The review about habit and climate change suggested that implementation intentions and gamification may be two effective technique to disrupt the meat consumption (17). Finally, the reported studies in review about the affects and emotions for climate change communication were mostly experimental. However, the authors suggested the ineffective role of threatening messages to modify the health behavior has not been verified for pro-environmental behaviors (16).

This article is a first attempt to identify the evidence based contents of future sustainable diet interventions. I recommend the well-designed protocol of Bianchi et al. , particularly their intervention logic model.

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