Diet-related greenhouse gases emissions according to individual readiness to reduce meat consumption

BACKGROUND: Reducing greenhouse gases emissions (GHGe) requires drastic changes in dietary patterns, notably reducing meat consumption. As the process of change can be experienced as stages, we might wonder what actual changes in diet-related GHGe result from each stage of meat reduction. We therefore aimed to describe levels of diet-related GHGe and their change over time according to the individual readiness to reduce meat consumption. METHODS: Food consumptions of 13,635 non-vegetarian French adults participating in the NutriNet-Santé Cohort were assessed using a food frequency questionnaire at two time points, in 2014 and 2018. Diet-related GHGe were assessed using life cycle assessment. A questionnaire in 2018 allowed us to characterize participants by their level of readiness to reduce meat consumption, using the stages of change from the transtheoretical model: precontemplation, contemplation/preparation, action, maintenance. Energy-adjusted diet-related GHGe were compared according to stages in 2014 and 2018 using ANCOVA and compared over time using Student test. Dietary intakes and their contribution to diet-related GHGe were also described. RESULTS: Individuals in the maintenance stage had the lowest diet-related GHGe, with an average of 3.73 kg CO2eq/day (SEM=0.02) in 2018, representing a difference of -26% compared to the precontemplation stage. Only participants in the action and the maintenance stages decreased their diet-related GHGe over time (both p < 0.0001). Specifically, GHGe from ruminant and monogastric meat (e.g. pork, chicken) decreased over time for the last two stages (all p < 0.0001), while their GHGe from cheese increased. CONCLUSIONS: The last two stages of meat reduction resulted in a reduction of diet-related GHGe. As this reduction is not sufficient to meet GHGe reduction objectives, further efforts are needed and new levers, combined with public health guidelines must emerge to enhance the transition. KEY MESSAGES: • Individuals with higher readiness to reduce meat consumption actually reduce their overall GHGe, mostly due to reduced consumption of ruminant meat, but also pork and poultry. • Observed reduction in diet-related GHGe is not yet sufficient to meet GHGe reduction objectives and further efforts are required.