Who Needs the Biggest Nudge? Personality Offers Clues to Interest in Eating Less Meat

The experiment found the clearest support for health messages, with some of the largest estimated responses appearing among people whose personality scores suggested they might need more encouragement to consider dietary change.

Eating less meat can feel easier to consider when the reasons connect with everyday life, from personal health to the food bill or concern for the environment. A flexitarian diet keeps animal products on the menu in moderate amounts and puts plant-based foods at the centre of meals, offering an option for people who do not want to become vegetarian or vegan.

Researchers at the University of Warwick examined how those different reasons influence willingness to change in "Benefit framing, personality traits and intention to adopt a flexitarian diet," published in Frontiers in Nutrition on 15 October 2026. The experiment found the clearest support for health messages, with some of the largest estimated responses appearing among people whose personality scores suggested they might need more encouragement to consider dietary change.

Three messages, one everyday food decision

The online experiment took place in June 2025 and recruited 412 UK adults through Prolific. The final analysis included 303 participants after checks for incomplete or inattentive responses, exclusions of people already following structured diets, and removal of missing answers. Participants were randomly assigned to four groups, each receiving the same definition of a flexitarian diet.

One group received no extra benefit information, creating a comparison group. The other groups read about potential annual food-cost savings, reductions in premature mortality risk, or lower diet-related carbon emissions. These were information messages about possible benefits, rather than changes to food prices, availability or the meals participants received.

Before seeing the messages, participants completed a short Big Five questionnaire covering openness, conscientiousness, extraversion, agreeableness and neuroticism. They later rated their agreement with adopting a flexitarian diet starting that day, with "agree" and "strongly agree" counted as positive intentions. Across the final sample, 45.9% expressed willingness to adopt the diet; the researchers did not observe whether anyone changed their eating habits.

Health benefits gave intentions the clearest lift

In the fully adjusted analysis, health messaging increased the predicted probability of a positive adoption intention by approximately 17 percentage points compared with the group receiving no additional information. Estimated increases for environmental and financial messages were around 9.5 and 0.9 percentage points, respectively, with neither providing clear evidence of an overall effect.

The initial comparison between groups did not detect a clear effect from any message. The health result emerged after the researchers accounted for participants' backgrounds, attitudes and personality, and remained evident in alternative analyses using the full five-point response scale. That makes health framing the best-supported message in this experiment, rather than proof that every health campaign will persuade people to reduce meat consumption.

Participants' existing attitudes also mattered. A one-point increase on the five-point environmental-morale scale, which measured willingness to contribute financially to environmental protection, was associated with a 15.3-percentage-point increase in predicted willingness. Each additional point on the ten-point risk-taking scale was associated with a 3.8-percentage-point increase, linking greater comfort with risk to greater interest in dietary change.

The biggest nudge reached people with more room to change

Without extra benefit information, people scoring higher in openness and conscientiousness were already more willing to consider a flexitarian diet. Openness reflects receptiveness to new experiences, and conscientiousness includes qualities such as organisation and self-discipline. A one-standard-deviation increase in these traits was associated with 12.8- and 9.1-percentage-point higher probabilities of positive intentions, respectively, in the comparison group.

The strongest estimated message effects appeared at lower trait scores. At one standard deviation below average openness, health messages increased predicted willingness by 36.5 percentage points and environmental messages by 25.5 percentage points. Health messaging produced a 32.9-point increase at similarly low conscientiousness. At above-average levels of these traits, the corresponding messages did not produce clear additional increases.

The researchers interpret this pattern as a possible ceiling effect: people already receptive to dietary change have less room for their intentions to rise. It does not establish that health or environmental messages discouraged those with higher scores. The result also challenged the expectation that health messages would work especially well among highly conscientious people.

Within the financial-message group, a one-standard-deviation increase in extraversion was associated with an 11.2-percentage-point lower probability of positive intentions. An equivalent increase in conscientiousness was associated with an 11.3-point higher probability in the environmental group. Agreeableness and neuroticism showed no consistent associations, and predictions linking agreeableness to stronger responses to particular messages were unsupported.

What the findings mean beyond the survey

The study found no convincing support for financial messages being especially effective among lower-income respondents or health messages working better among older adults. In the main analysis, adults aged 35–44 were more willing than those aged 18–34, and respondents earning £50,000–£74,999 were less willing than those earning below £25,000; the age result did not hold in alternative analyses, and the income pattern varied.

Health messaging, environmental morale and risk-taking retained their positive relationships with intentions. The patterns involving financial messages and extraversion, and health messages and conscientiousness, also persisted. The openness-related message patterns were less consistent, making those findings more tentative.

The experiment measured immediate, self-reported intentions rather than purchases, meals or lasting changes, used a brief personality questionnaire, and included a UK online sample skewed to higher education. For public-health bodies, retailers and local authorities, health benefits offer a promising starting point for testing communication about flexitarian eating.