We might expect our food choices to affect the choices of those around us and vice versa. But do we appreciate how significant this effect can be? Are some people’s dietary choices more susceptible to social influences than others? Is there a limit to that influence?

These are just a few of the questions researchers set out to answer in a study published in 2018 in the journal Appetite.^[1] For the better part of a year, the researchers sneakily recorded what people ordered for lunch at a Vancouver cafe restaurant where customers queued and in which they could choose between comparable vegetarian and meat options (e.g., a stew with a meat base versus a lentil base). After collecting information on what people ordered, the researchers surveyed those who consented to be part of the study, asking questions about those individuals’ dietary habits, their relationship to the person in the line ahead of them, and whether they might have been aware of social forces at work in their decision-making process.

The primary question the researchers wanted to answer was whether people’s orders were influenced by the orders of those in front of them. What they found might surprise you. And it could improve our appreciation for what it means to be a good role model. But before we get into the details, let’s define some critical terms.

What Is Modeling?

As defined by the researchers, modeling, in the context of food, is “the phenomenon whereby people mimic the food intake or choice of another person.”^[1]

Notice that choice is only half of the modeling equation. Research on intake, the other half, is already more established. A 2015 meta-analysis of 38 articles found a significant modeling effect for food intake: “Participants ate more when their companion ate more, and ate less when their companion ate less.”^[2] Interestingly, the modeling effect was greater for women than men. It was also greater as an inhibiting effect than as an augmenting effect. In other words, although people model food intake when the outcome is eating more, they are apparently even more likely to model food intake in the opposite direction—when their companion eats less. This makes sense given that in most social contexts, not overeating is an injunctive norm, especially for women (injunctive norms are those that people perceive as being approved or not approved; they are what we think we ought to do). It seems reasonable that this injunctive norm might reinforce the inhibitory modeling effect.

Food choice modeling can be trickier to study, particularly with entrees.^[1] In more rigorously controlled studies, participants may be especially susceptible to social influence because of the heightened uncertainty of finding themselves in an unfamiliar environment and knowing they are being studied. Observational studies, like the 2018 study, can capture behavior in a more natural environment, but it is difficult to rule out other influences on food choice or to generalize the findings to the broader population.

Vegetarian or Meat?

Now, getting back to the lunchtime cafe at the University of British Columbia, Vancouver.^[1] After starting with 269 consenting participants and excluding those who knew the person in line ahead of them or those who were already vegetarian or vegan, the researchers were left with 174 participants.

The headline finding was that individual orders matched the person in front of them at a rate significantly greater than would be expected by chance. In other words, it seems that customers were indeed modeling the food choices of those in front of them. “Following a prior meat-based order, the proportions of meat-based orders increased from 73% to 82%,” exceeding the rate one would expect from chance alone. What is encouraging is that the modeling effect seemed even greater for vegetarian orders: “Following a vegetarian order, the vegetarian orders increased from 27% to 47%.”

Do We Know the Forces That Move Us?

What we found most fascinating about the study is that more than three-fourths of the participants claimed to have not been influenced by the prior order. Still, the modeling effect was significant even among that group. This suggests that modeling may occur beyond our awareness, a notion well-supported by the wider scientific literature on social influence.^[3] Generally, we underestimate external influences on our choices, perhaps because we desire to feel control over our destinies. One exception is when admitting to external influences supports self-serving biases. For example, women in a pasta-feeding study were more willing to cite external influences (portion size) as an “excuse” for overeating.^[4]

While participants may have been influenced “simply [by] witnessing the prior order being prepared,” the researchers note that the meal choices were all in an open display, so visual prominence is unlikely to be the sole factor driving order-matching. Other limits of the study include its relatively small sample size and—I suspect more importantly—its location on a university campus. It is impossible to know whether an equally robust modeling effect might occur in different settings with populations not predominantly made up of students, who may be more susceptible to social influence or more open to shifting toward plant-based diets.

The Power of Being a Good Role Model

Given the many health and environmental benefits of switching to a plant-based diet, there is a growing interest throughout the plant-based movement in how we might more effectively encourage behavior change in others. To successfully and quickly address the global crises related to animal food consumption, all of us—policymakers, entrepreneurs, researchers, and every individual consumer in between—must better promote the strategies that work. Equally, it would be useful to know which strategies are counterproductive so we can avoid them.

This is easier said than done. Because we are dealing with relatively new areas of study, there remain many more questions than answers. The effectiveness of confronting people with information is unclear. So much depends on the type of information you share and the circumstances in which you share it. In some cases, even seemingly harmless approaches might backfire. I’m sure many of you can think of a few examples in which trying to start a conversation about a plant-based lifestyle might do more to shut down interest than to inspire change.

To further complicate the issue, social norms do not always work as expected. In a study published earlier this year, researchers found small and statistically insignificant effects of social norms on first-year students “confronted with different statements about the diets of students already enrolled and studying at the university.”^[5] Notably, they found that female students were much more responsive to this explicit exposure to social norms than their male counterparts, especially when their food choices could be observed by others. In another study, researchers found that norm following is likelier to occur when norms are conveyed implicitly and the circumstances do not feel unfamiliar; however, participants who had low intentions to follow a vegetarian diet from the beginning of a study “[exhibited] reactance against an explicit vegetarian norm in an unfamiliar context [emphasis added].”^[6] That is, those who were not interested in the vegetarian diet in the first place became even less likely to choose vegetarian options when confronted with an explicit norm. Intuitively, this makes sense. We have probably all met someone, at some point, who exhibited this kind of stubbornness.

One thing that cannot backfire, though, is being a positive role model. While more research in this area is needed, we now have at least some compelling evidence that our example alone can inspire others to choose healthier options, whether we know it or not—even whether they know it or not! So make sure to continue treating yourself well: eat wholesome foods, prioritize learning, exercise regularly, and cultivate a healthy social life. You never know who might be watching.

(Learn more about spheres of influence and sparking change in others from our Plant-Based Nutrition Certificate.)

References

1. Christie CD, Chen FS. Vegetarian or meat? Food choice modeling of main dishes occurs outside of awareness. Appetite. 2018;121:50-54. doi:10.1016/j.appet.2017.10.036
2. Vartanian LR, Spanos S, Herman CP, Polivy J. Modeling of food intake: A meta-analytic review. Social Influence. 2015;10(3): 119–136. doi:10.1080/15534510.2015.1008037
3. Prabhakaran R, Gray JR. The pervasive nature of unconscious social information processing in executive control. Front Hum Neurosci. 2012;6:105. Published 2012 Apr 26. doi:10.3389/fnhum.2012.00105
4. Vartanian LR, Reily NM, Spanos S, Herman CP, Polivy J. Evidence of a self-serving bias in people’s attributions for their food intake. Appetite. 2024;201. doi:10.1016/j.appet.2024.107583
5. Dannenberg A, Klatt C, Weingärtner E. The effects of social norms and observability on food choice. Food Policy. 2024;125. doi:10.1016/j.foodpol.2024.102621
6. Hammami A, Garcia A, Darcel N, Higgs S, Davidenko O. The effect of social norms on vegetarian choices is moderated by intentions to follow a vegetarian diet in the future: Evidence from a laboratory and field study. Front Psychol. 2023;14:1081700. Published 2023 Mar 8. doi:10.3389/fpsyg.2023.1081700