The "Eat Less Meat" one-month challenge: a randomized controlled trial of a meat reduction pledge intervention among...

Encouraging the shift towards more plant-based diets in new generations is one of the major current challenges to preserve population and planetary health. Personal pledges to reduce meat consumption could motivate behaviour change, but have received limited scientific testing. We examined the effect of a "Eat Less Meat" one-month challenge on immediate and long-term meat consumption of university students.

In January 2023, 366 university students (21 ± 3.2 years old) consented to participate in the "Eat Less Meat" one-month challenge and were randomized to the intervention group (n = 187, challenge in February 2023) or the wait list control group (n = 179, challenge in June 2023). Neither participants nor investigators were masked to group assignment. Participants chose between three meat reduction objectives: consuming meat 0, 3, or 6 times a week. They received a meat-free recipe book and followed an Instagram account where motivational information was posted daily during one month. All the participants completed a food frequency questionnaire in January (T0, before), February (T1, during), and May 2023 (T2, three months after the challenge) and data on meat consumption were analysed using linear mixed models.

The participants in the "Eat less meat" one-month challenge reduced their meat consumption by -67 g/day (95% CI [-82; -53]) during the challenge and by -50 g/day (95% CI [-68; -31]) three months later. The decrease was greater than in the control group by -34 g/day (95% CI [-55; -14]) during the challenge, but there was no significant difference between intervention and control group at three months follow-up.

The "Eat Less Meat" one-month challenge may be a promising strategy to drive short-term reductions in meat consumption and further work to improve longer-term effectiveness is now warranted.

The trial was pre-registered prior to data collection at Clinicaltrials.gov (NCT05752786).