Many studies find meat overconsumption has high health and environmental costs. High intake of red and processed meat is linked to cancer, heart disease, and diabetes. Meat production worsens climate change through carbon and methane emissions apart from driving deforestation and water pollution through fertilizer use. Antibiotics used in livestock lead to antimicrobial resistance in both animals and humans.
So, in 2019, the EAT-Lancet Commission, a consortium of nutrition, health, and ecology experts from over 16 countries, reviewed the science and concluded that we need to cut down consumption of red and processed meat. A healthy and environmentally sustainable 2,500-calorie per day diet (for an average-weight 30-year-old) would allow around 98 grams—or one serving—of red meat per week. That’s less than one-quarter of what a typical American consumes! More broadly, rich countries consume around 2.6 times more meat than low-income countries.
Clearly, a healthy, planet-friendly diet means lowering red meat intake and promoting vegetarian foods. But people are quite attached to their meaty diets, so persuading them to change is challenging.
Focusing On Personal And Planetary Benefits
The way people think about causes and consequences is called “framing.” We wanted to find out what was the most effective way of framing the goal of helping people change their dietary habits: this goal could be framed in terms of personal well-being, or in terms of planetary well-being. Or, the framing could include both at once.
There is a debate about whether focusing on personal benefits (your health, your finances) versus public, environmental benefits (for our planet) is more effective. A widespread assumption is that people are more motivated to help themselves, rather than the planet, because they are put off by being asked to make a personal “sacrifice.” However, there is also a concern that appealing to self-interest may lead people to behave selfishly in subsequent choices, because they remain in a self-interested mindset.
A third view is that appealing to both the personal health and public environmental co-benefits (help yourself by having a healthier life, and also help the planet) is the way to go, as it draws on both self-interest and environmental concern.
So, we designed planning prompts which incorporated these different motivations. Planning prompts are modified if-then plans, where people are asked to think about when, where, and how they would be willing to take a desired action. The main idea is that making plans with prompts like this can help people recall in the right circumstances and in the right moment that they need to carry out a task, making follow-through more likely.
In our research, we exposed people to pre-designed planning prompts that specified when, where, and how one would eat a more vegetable diet, apart from why (for personal or planetary health). Plans like: IF I am tempted to snack after a stressful day, THEN I will have fruits and vegetables for the ENVIRONMENT). We only varied the “why”: for one’s personal health, the environment, or both, as we were interested in checking the effect of different motivations.
Our study was done online in the UK with around 1,200 people. They first read a short blurb about either the personal, planetary, or both the personal and planetary benefits of eating less red meat and eating more veg. Then, they answered the if-then type of statements we described. Finally, they could (hypothetically) choose a menu item from a well-known restaurant.
We found that all three frames—personal health, planetary health, and both personal and planetary health—were equally effective at doubling the likelihood of choosing a veg option, compared to a control group who saw no information and made no plan.
But there’s more: Those in the personal and planetary co-benefits condition were more likely than the control condition to donate to a charity following the food choice task, suggesting that drawing on both self-interested and environmental motivations increased their veg choices in the hypothetical situation and had a positive spillover on subsequent helping behavior.
But Wait, There’s Even More
To check if our encouraging results lasted, we also got back to the same people to find out how often they reported eating veg food three days later and then again two months later. The good news is that those in the combined personal and planetary benefits condition reported eating more veg food three days after the experiment compared to the control group. However, this didn’t last for as long as two months. Even so, we were happy that our simple one-time method of using planning prompts about how, where, and when one would eat less meat—and focusing on the motivation to help yourself and help the planet—may nevertheless be a good start!
For Further Reading
Shreedhar, G., & Galizzi, M. M. (2021). Personal or planetary health? Direct, spillover and carryover effects of non-monetary benefits of vegetarian behavior. Journal of Environmental Psychology, 78, 101710.
Ganga Shreedhar is an Assistant Professor in Behavioural Science at the London School of Economics and Political Science (LSE). She investigates how to motivate and scale consumer and citizen behaviors, including via spillover and carryover effects, in ways that simultaneously benefit people and the planet.
Matteo M. Galizzi is an Associate Professor of Behavioural Science at the LSE. He specializes in health and public policy, including the spillover and carryover effects of behavioral interventions.
Magnifying Inequity: Women’s Lives During the COVID-19 Global Pandemic
Making the Moral Case in Politicized Health Messaging
