This post summarizes a new preprint from the Humane and Sustainable Food Lab at Stanford titled “Taking a bite out of meat, or just giving fresh veggies the boot? Plant-based meats did not reduce meat purchasing in a randomized controlled menu intervention.”
The paper reports on an online RCT where participants were asked to select taco fillings from one of three menus designed to mimic the options at Chipotle. They could choose from both meat- and plant-based options.
The randomized treatment was whether participants saw
- one plant-based option (veggie & guacamole)
- two (veggie + ‘Sofritas,’ an existing plant-based meat analogue (PMA) that you can get at Chipotle)
- or three (veggie + Sofritas + ‘Chick’nitas,’ a hypothetical chicken-analogue PMA).
The treatment was embedded in a series of decoy questions about choosing pens and t-shirts to obscure the purpose of the study.
The main outcome was whether people chose a meat-based taco filling or not. Our second outcome was whether Chick’nitas reduced demand for chicken specifically among meat-based options. All outcomes were hypothetical, and price was held constant.
4,431 people selected a taco filling.
We powered the study to detect a 5 percentage point (pp.) reduction in meat selection, the smallest effect size which we thought might prompt Chipotle or someplace similar to consider adding a new PMA.
Unfortunately, we didn’t find an effect of that magnitude.
Compared to having just veggies:
- adding Sofritas reduced demand for meat by 1.14 pp. (95% CI [-3.30, 1.02], p = .30).
- adding Sofritas and Chick’nitas reduced demand for meat by 2.14 pp (95% CI [-4.36, 0.08], p = .06).
Adding Chick’nitas modestly but insignificantly decreased demand for chicken, but simultaneously, demand for steak increased. Going from no PMAs to two decreased demand for veggies & guac from 9.2% to 5.7%.
See table below for full breakdown.
No-PMA Arm (n = 1,501) | Status Quo Arm (n = 1,479) | Chick’nitas Arm (n = 1,451) | |
| Chicken | 613 (40.8%) | 580 (39.2%) | 516 (35.6%) |
| Steak | 412 (27.4%) | 411 (27.8%) | 434 (29.9%) |
| Beef Barbacoa | 184 (12.3%) | 185 (12.5%) | 182 (12.5%) |
| Carnitas | 129 (8.6%) | 138 (9.3%) | 139 (9.6%) |
| Veggie | 138 (9.2%) | 98 (6.6%) | 83 (5.7%) |
| Sofritas | n/a | 56 (3.8%) | 40 (2.8%) |
| Chick’nitas | n/a | n/a | 42 (2.9%) |
| Declined to order | 25 (1.66%) | 11 (0.74%) | 15 (1.0%) |
| Meat | 1,338 (89.14%) | 1,314 (88.8%) | 1,271 (87.6%) |
| Non-meat | 138 (9.19%) | 154 (10.4%) | 165 (11.4%) |
Men, Republicans, people without a four-year college degree, and people who ate more than ten or more servings of meat per week were all more likely to select a meat-based taco filling than folks in other categories.
We don’t know if we’d have found bigger effects in stores. Our experiment didn’t include any sensory information, so perhaps the Chick’nitas would have been more appealing in person, but perhaps not.
Key takeaways
Making an additional plant-based option available did not meaningfully change meal selections. This held for both a long-standing PMA option (Sofritas) and a novel one (Chick’nitas). Reducing meat consumption is a hard problem, and achieving price-, taste-, and convenience- parity won’t obviously do the trick either.
Technology will likely play a large role if we are to transition away from factory farming, as it has for past externalities; but we also see an important role for culture and attitudinal change, as well as changing the choice architecture of meal environments and actively promoting plant-based options.
Thanks for doing and publishing this study! It's so helpful to get a clearer picture on this, even if we don't like the answers. As a validation of your findings, in 2015, Chipotle told Vox that sofritas were 3.5% of sales, very close to your 3.8%.
Interesting! I believe I missed that interview, although a rep told the Times that same year that "sofritas accounts for about 3 percent of fillings."
I recently learned that Steve Ellis (Chipotle founder) tried predominantly plant-based fast casual in 2024; apparently it didn't work out (although I'm still seeing a Yelp page?) and this winter he told Eater that “veganism...is very polarizing, I’ve learned.”
In a separate interview Ellis said “I think people will eat more plant-based diets and make that part of their life if there are better options,” [emphasis added], which I agree with. But I basically think that that no single effort is likely to change the game, in part because the most effective interventions are unusually challenging to scale.
(Also, Chipotle tried out free shipping on plant-based options in 2021, which is an intervention I'd love to formally evaluate! But I'd bet that appetite for that kind of thing is lower nowadays. The whole market is a long way from where it was then.)
I appreciate y'all studying this and helping us learn more about what we can do to advance plant-based options, and I especially love that it is open access. I do have some questions tho.
(A) "Despite widespread optimism, simply increasing the number of PMAs on restaurant menus may not consistently reduce meat selection." Is this a reasonable expectation of any new food ingredient? Are there studies that show just adding a new ingredient, any ingredient whether plant-based or not, to a menu would result in uptake of it?
It seems to me, and I could be missing something, that this study might be studying the habitual nature of consumers, and less so their preferences about plant-based meat. A possible way to have controlled for this would be to have a new animal meat item and see how many people chose it.
If your general model of consumers, or people generally, is that they are cognitive misers, it seems that model would predict this result regardless if the additional items were plant based or meat based. So the casual factor would be habit, not the kind of protein. That would still be informative for plant-adoption and be a large barrier, but it be saying less about plant-based preferences and more about just needing to do proper UX and marketing.
(B) I saw y'all did awareness checks on what people thought the point of the study was, but curious why y'all didn't do an awareness check on whether they noticed if there was a plant-based option in the menu or not? Like how many people are taking the time to read the small grey on white text? And with steak or chicken, you don't need to because those are familiar and instantly understood. Without that, it is unclear to me, whether you are testing people's preference for plant-based options or their ability to notice new items.
Hi Dorsal, thank you for your kind words about the work and thoughtful questions. I agree with Seth's reply and would add for (A), there is some evidence of this effect for plant-based foods in general, for example: Garnett 2019, Parkin 2021, and Pechey 2022. I don't know of any studies which have tested adding animal-based meats.
Hi Dorsal, good questions: