 According to a survey of more than 30,000 U.S. residents, a third of American adults self-identify as meat reducers, meaning one in three of us are trying to cut down on our meat consumption. Why? For those earning less than $40,000 a year, the number one reason is cost. For those earning more than $40,000 a year, the number one reason is health. And indeed, if we were to define a healthy diet, compared to how we're eating now, we should be eating more plant-based foods, including fresh fruits and vegetables, whole grains, legumes, meaning beans, split peas, chickpeas, and lentils, seeds, and nuts, and at the same time lower in animal foods, particularly fatty and processed meats. In an editorial entitled Plant-Based Diets for Personal Population and Planetary Health, co-authored by the Chair of Nutrition at Harvard, healthy plant-based diets are not only more sustainable, but have also been associated with lower risk of chronic diseases, such as obesity, type 2 diabetes, cardiovascular disease, and some cancers. What do we mean by plant-based? Basically, any diet that reduces the amount of animal products and increases the amount of plants, again, vegetables, fruits, whole grains, legumes, nuts, and seeds. Transitioning global diets towards healthy plant-based dietary patterns would require large-scale public health efforts, but could be instrumental in ensuring future human and planetary health. Indeed, the IPCC, the Intergovernmental Panel on Climate Change, describes plant-based diets as a major opportunity for mitigating and adapting to climate change, and includes a policy recommendation to reduce meat consumption. OK, but how do you do it? In a systematic review of experimental studies on strategies to reduce meat consumption, one of the most effective experiments came out of the Midwest. Sadly, research shows that the provision of information on its own can be of limited utility in facilitating behavioral change. However, default interventions have been successfully employed in a variety of pro-social contexts, making the right option or the healthiest option the easiest option, the default option. Take, for example, organ donation. Every year, thousands of people in the United States have died waiting for a suitable donor organ. But wait, 85% of Americans approve of organ donation, yet less than half have made a decision about donating and fewer still have granted permission by signing a donor card. If you look at Europe, there's nearly a tenfold difference in the organ donor rates across different countries. In some countries, consent is only about 10%, while in others, it's up to like 99.9%. Oh, what's the difference between the two colors? Gold is opt-in, blue is opt-out. In opt-out countries, the default is that people are organ donors unless they actively register not to be. In the opt-in countries like the United States, the default is nobody is an organ donor without explicitly registering to be one. So there's all sorts of calls for campaigns to change public attitudes about organ donation, but remember, 85% are already on board. If we want to change behavior and not just attitudes, changing the default condition may be more effective. So does it work for diet? In the default treatment, participants received at their table a menu listing only five meat-free options, but they were informed verbally and in writing on the menu that they could also consult a second menu that was posted on the wall about a dozen feet away, which had your standard array of popular non-vegetarian dining hall dishes. And in the control condition, both lists of options were mixed together on the same menu they were handed. And when you do that, only a minority of people choose the meat-free options, between 5% and 40%, depending on if you describe the meat-free options in an appealing way, like pasta with provolso vegetables or in unappealing terms like vegan calzone. Okay, but what about the default condition where the menu in front of them is all meat-free? They can still get up and order all the meat they want, but the alternate menu is a few steps away. You're not taking away any people's options, but just by making it the default, meat-free choices shot up like to 75% and 90%. Even an unappealingly described meat-free option totally won out. And even just adding more veg options from a quarter of the option to half the options may increase the sales of the veg options between about 40% to 80%.