Abstract
Reducing meat consumption could protect the environment and human health. We tested the impact of a behavioral intervention to reduce meat consumption. Adult volunteers who regularly consumed meat, were recruited from the general public and randomized 1:1 to an intervention or control condition. The intervention comprised free meat substitutes for four weeks, information about the benefits of eating less meat, success stories, and recipes. The control group received no intervention or advice on dietary change. The primary outcome was daily meat consumption after four weeks, assessed by a 7-day food diary, and repeated after eight weeks as a secondary outcome. Other secondary and exploratory outcomes included the consumption of meat substitutes, cardiovascular risk factors, psychosocial variables related to meat consumption, and the nutritional composition of the diet. We also estimated the intervention’s environmental impact. We evaluated the intervention using generalized linear mixed effects models. Between June 2018 and October 2019, 115 participants were randomized. Baseline consumption was 134 g/d in the control and 130 g/d in the intervention group. Relative to the control, the intervention reduced meat consumption at 4 weeks by 63 g/d (95%CI: 44, 82, p<0.0001, N=114) and at eight weeks by 39 g/d (95%CI: 16, 62, p=0.0009, N=113), adjusting for sex and baseline consumption. The intervention significantly increased the consumption of meat substitutes without changing the intake of other principal food groups. The intervention increased intentions, positive attitudes, perceived control, and subjective norms of eating a low meat diet and using meat substitutes, and decreased attachment to meat. At 8 weeks, 55% of intervention recipients identified as ‘meat-eaters' compared to 89% in the control. A behavioral program involving free meat substitutes can reduce meat intake and change psychosocial constructs consistent with a sustained reduction in meat intake.
Generated Summary
This study presents the results of a randomized controlled trial (RCT) called Replacing meat with alternative plant-based products (RE-MAP), which investigated a multicomponent behavioral intervention designed to reduce meat consumption. The trial recruited adult volunteers who regularly consumed meat and randomized them into either an intervention or a control condition. The intervention group received free meat substitutes, information on the benefits of eating less meat, success stories, and recipes. The primary outcome was daily meat consumption assessed at four weeks and eight weeks. Secondary outcomes included the consumption of meat substitutes, cardiovascular risk factors, psychosocial variables related to meat consumption, and the nutritional composition of the diet. The intervention was designed to assess the impact of providing free meat substitutes on meat consumption and related factors. The study was conducted in Oxford, UK. The study’s focus was to determine whether participants could reduce their meat consumption when given meat-free replacements and to assess the effects after the intervention ended. The study also aimed to explore the impact of the intervention on recipients’ dietary intakes, psychosocial variables related to meat intake, and cardiovascular risk factors.
Key Findings & Statistics
- Between June 2018 and October 2019, 115 participants were randomized.
- Baseline meat consumption was 134 g/d in the control group and 130 g/d in the intervention group.
- Relative to control, the intervention reduced meat consumption at 4 weeks by 63 g/d (95% CI: 44, 82, p<0.0001, N=114) and at eight weeks by 39 g/d (95% CI: 16, 62, p=0.0009, N=113).
- In the BOCF analysis, relative to the control group, the intervention reduced meat consumption by 61 g/d (95% CI: 42, to 80, p<0.0001) at four weeks and 38 g/d (95% CI: 15, to 66, p=0.0011) at eight weeks.
- The intervention significantly increased the consumption of meat substitutes without changing the intake of other principal food groups.
- At 8 weeks, 55% of intervention recipients identified as ‘meat-eaters’ compared to 89% in the control.
- The proportion of participants adopting a meat-reduced or meat-free eating identity in the intervention group was 27% (vs 9% in the control group) at four weeks and 45% (vs 11% in the control group) at eight weeks.
- The intervention led to a significant reduction in body weight -0.6 kg (95% CI: -1.2, -0.1) at 8 weeks.
- In the intervention group, total meat consumption decreased from 130 g/day at baseline to 51 g/day after 4 weeks and 81 g/day after 8 weeks. In the control group meat consumption was 116 g/day at 4 weeks and 122 g/day at 8 weeks.
- The intervention reduced greenhouse gas emissions from diets by 10.5 kg CO2-equivalent per week, compared to the control group, after 8 weeks.
- The intervention reduced land use from diets by 23.6 m2 per week, compared to the control group, after 8 weeks.
Other Important Findings
- The intervention increased intentions, positive attitudes, perceived control, and subjective norms of eating a low meat diet and using meat substitutes and decreased attachment to meat.
- The intervention did not significantly alter body composition, blood pressure, or lipid fractions.
- The intervention provided early evidence that the intervention significantly reduced the GHG emissions (in CO2-eq) and the land requirements of recipients’ diets at both follow-ups.
- The intervention increased the likelihood of taking up a meat-reducing or non-meat-eating identity.
- The study provided evidence for a statistically significant reduction in greenhouse gas emissions and land use from participants’ diets.
- There was no evidence that the intervention meaningfully changed the nutritional composition of participants’ diets relative to the control.
Limitations Noted in the Document
- The multicomponent nature of the intervention made it difficult to quantitatively assess which intervention component(s) causally influenced the outcomes.
- The sustained intervention effect at eight weeks might reflect eating up free supplies rather than new purchases.
- Participants were only recruited among adult-only households close to Oxford.
- Participants were not blind to the group allocation and may have felt greater motivation to respond to the intervention.
- The food diaries themselves might have influenced participants’ meat consumption.
- The manual disaggregation of meat from food diaries may have introduced some non-differential error in the measurement of the primary outcome.
- Environmental impact data were not available for every food group included in the analysis.
- The analysis focusing on GHG emissions was based on an aggregate measure of GHGs (i.e. CO2-eq).
Conclusion
The study’s findings suggest that using free meat substitutes as a method to reduce meat consumption is effective and results in decreased meat consumption. The results of RE-MAP suggest that harnessing the mere exposure effect from providing meat substitutes is an effective way to reduce meat consumption. The study also shows that people using meat substitutes, who are motivated to reduce their consumption, swap meat for substitutes without changing other aspects of their diets. The costs of the intervention mean that RE-MAP is unlikely to be a scalable option in its current form, but it shows that increasing exposure to, and consumption of, meat substitutes can lead to important reductions in meat intake also after the intervention. Other interventions which might work through similar mechanisms to achieve population-level impact include repositioning meat substitutes products in more prominent areas of grocery stores, providing vouchers for meat substitutes or free tasters, or incentivizing customers to replace meat with meat substitutes when shopping online. Previous studies showed that providing meat substitutes for free as part of a wider behavioral intervention was associated with reduced meat consumption during and after the intervention. Encouraging intervention recipients to transition from meat substitutes to a more traditional plant-based diet might therefore require additional active interventions. The study emphasizes the potential of these types of interventions to contribute to sustainable food systems.