Health-focused messages are significantly more effective at encouraging people to adopt a flexitarian diet than environmental or financial arguments, according to a 2026 randomized controlled trial of 303 UK adults. Gram Research analysis found that health framing increased adoption intentions by approximately 17 percentage points compared to no message, with even stronger effects (up to 36.5 percentage points) for people with naturally curious or conscientious personalities.
A new study from Gram Research analysis found that the way you talk about eating more plants matters a lot. Researchers tested different messages on over 300 UK adults, telling some groups about health benefits, others about saving money, and others about helping the environment. The health message worked best, making people about 17% more likely to want to try eating more plant-based foods. But here’s the interesting part: the same message didn’t work equally for everyone. People with certain personality traits responded much better to different types of messages, suggesting that one-size-fits-all campaigns might miss the mark for many people.
Key Statistics
A 2026 randomized controlled trial of 303 UK adults found that health-focused messages increased willingness to adopt a flexitarian diet by approximately 17 percentage points compared to a control group receiving no message.
Among participants who were one standard deviation below average in openness, health framing increased adoption intentions by 36.5 percentage points, suggesting that health messages may be especially persuasive for people less naturally inclined toward dietary experimentation.
Environmental and financial framing produced no statistically significant effects on flexitarian diet adoption intentions in the overall sample, despite previous research suggesting these messages might be motivating.
People scoring high on environmental morale and willingness to take risks showed greater adoption intentions for a flexitarian diet, indicating that underlying values and personality traits influence dietary behavior beyond the effects of specific messages.
The Quick Take
- What they studied: Whether different ways of explaining the benefits of eating more plant-based foods (flexitarian diet) would convince people to actually try it, and whether certain personality types responded better to different messages.
- Who participated: 303 adults living in the UK who participated in an online experiment. They were randomly split into groups that received different types of messages about eating more plants.
- Key finding: Health-focused messages worked best, increasing people’s willingness to try a flexitarian diet by about 17 percentage points compared to no message at all. However, for people who were naturally more open-minded or conscientious, the effect was much stronger, sometimes reaching 36.5 percentage points.
- What it means for you: If you’re trying to convince someone to eat more plant-based foods, talking about health benefits is your best bet. But the approach might need to be tailored based on who you’re talking to. People who are naturally curious and open to new ideas may respond especially well to health messages, while others might need a different angle.
The Research Details
Researchers conducted an online experiment where 412 UK adults were randomly assigned to receive one of four different messages about eating more plant-based foods. One group received information about health benefits, another about saving money, a third about environmental benefits, and a control group received no special message. After reading their assigned message, participants answered questions about whether they’d be willing to try eating this way. The researchers then analyzed the results using statistical models that could show how different personality types responded to each message type.
The study used a randomized controlled trial design, which is considered one of the strongest ways to test whether something actually works. By randomly assigning people to different groups, researchers could be more confident that any differences in responses were due to the messages themselves, not other factors. The researchers also measured personality traits using established psychological questionnaires, allowing them to see which personality types were most influenced by each type of message.
The final analysis included 303 participants after some were excluded for incomplete responses. This sample size is large enough to detect meaningful differences between groups, though it’s still a relatively modest number for drawing broad conclusions about entire populations.
Understanding what messages actually convince people to change their eating habits is crucial for public health efforts and environmental sustainability. If health messages work better than environmental messages, for example, public health campaigns should focus on health benefits. But if different people respond to different messages, then a one-size-fits-all approach will fail to reach many people. This research helps identify which communication strategies are most effective and for whom, making it possible to design better, more targeted campaigns.
This study has several strengths: it used a randomized design, which reduces bias; it measured actual intentions rather than just asking people what they think; and it looked at how personality traits modify the effects of messages. However, the study only measured intentions to adopt a flexitarian diet, not actual behavior change, so we don’t know if people who said they’d try it actually did. The sample was also limited to UK adults who participated online, so results may not apply to other countries or populations. Additionally, the study was conducted in 2026, making it very recent research.
What the Results Show
Health-focused messages were the clear winner in this experiment. When people received information about the health benefits of eating more plant-based foods, they were about 17 percentage points more likely to express a positive intention to try this diet compared to the control group that received no special message. To put this in perspective, if 40% of people in the control group said they’d try it, about 57% of people who received the health message said they would.
Financial messages (about saving money) and environmental messages (about protecting the planet) did not produce statistically significant effects overall. This doesn’t mean these messages are worthless, but it does suggest they’re less effective than health messages at convincing people to adopt a flexitarian diet.
However, the story becomes more nuanced when personality traits enter the picture. The researchers found that certain personality characteristics made people more or less responsive to the messages. People who scored high on openness (a tendency to be curious and open to new experiences) and conscientiousness (being organized and responsible) were naturally more interested in trying a flexitarian diet, even without any special message. Among people who were less open or conscientious, health framing had a much stronger effect, increasing adoption intentions by 36.5 percentage points for openness and 32.9 percentage points for conscientiousness.
Two other factors predicted willingness to adopt a flexitarian diet: environmental morale (caring about environmental issues) and willingness to take risks. People who cared more about environmental problems and who were comfortable taking risks were more likely to express positive intentions about trying a flexitarian diet. This suggests that beyond the specific messages tested, people’s underlying values and personality traits play important roles in dietary choices.
This research adds important nuance to existing studies on dietary behavior change. Previous research has shown mixed results about whether environmental or health messages work better for promoting plant-based eating. This study helps explain why: the effectiveness depends heavily on who you’re talking to. The finding that health messages work better than environmental messages aligns with some previous research suggesting that personal health concerns are often more motivating than abstract environmental concerns for most people. The discovery of personality-dependent effects is relatively novel and suggests that future interventions should be more personalized.
The biggest limitation is that this study measured intentions, not actual behavior. People often say they’ll do something but don’t follow through. We don’t know if the people who expressed positive intentions actually changed their diets. Second, the study only included UK adults who were willing to participate in an online experiment, so results may not apply to other countries, older adults, or people without internet access. Third, the messages were presented in a simplified, experimental setting that may not reflect how people encounter dietary information in real life. Finally, while the study found that health framing worked best overall, the effect sizes were modest, and the study couldn’t determine why health messages worked better than environmental messages.
The Bottom Line
If you’re trying to encourage someone to eat more plant-based foods, emphasize the health benefits. This approach has moderate to strong evidence of effectiveness, especially for people who are naturally curious or conscientious. For people who are less open to new ideas, health messages may be particularly persuasive. Environmental and financial arguments appear less effective overall, though they may still matter for specific individuals. Consider tailoring your approach based on what you know about the person’s values and personality.
Public health officials and nutritionists should care about these findings when designing campaigns to promote plant-based eating. Food companies and restaurants promoting plant-based options should also consider using health-focused messaging. Individuals trying to convince friends or family to eat more plants might benefit from emphasizing health benefits. However, these findings are based on stated intentions in an online experiment, so they should be combined with other evidence before making major policy decisions. People in countries outside the UK should be cautious about assuming these results apply to their populations.
This study measured immediate intentions, so we don’t know how long any motivation lasts. In real life, people often feel motivated to make dietary changes but struggle to maintain them over time. You might expect that someone who receives a health message would feel more motivated to try a flexitarian diet within days or weeks, but whether they actually stick with it for months or years is unknown. Behavioral change typically requires repeated reinforcement and support, so a single message is unlikely to produce lasting change on its own.
Frequently Asked Questions
What’s the best way to convince someone to eat more plant-based foods?
Focus on health benefits rather than environmental or financial arguments. Research shows health-focused messages increase adoption intentions by about 17 percentage points. The effect is even stronger for people who are naturally curious or conscientious, where health messages can increase intentions by up to 36 percentage points.
Do environmental messages work for getting people to eat more plants?
Environmental messages alone did not produce statistically significant effects in this study, though people who already care about environmental issues were more interested in flexitarian diets. Health messages appear to be more universally persuasive than environmental arguments for dietary change.
Does personality affect how people respond to messages about eating more plants?
Yes, significantly. People who are naturally open-minded and conscientious responded much more strongly to health messages, with adoption intentions increasing by 36.5 and 32.9 percentage points respectively among those scoring low on these traits. This suggests tailored messaging based on personality could improve effectiveness.
Will people who say they’ll try a flexitarian diet actually change their eating habits?
This study measured intentions, not actual behavior, so we don’t know if stated willingness translates to real dietary change. People often intend to make changes but struggle to follow through, so additional support and reinforcement beyond initial messaging is likely necessary.
Can these findings be applied to people outside the UK?
The study included only UK adults in an online experiment, so results may not apply to other countries, cultures, or populations. Different regions have different food cultures and values, which could affect how people respond to various messages about plant-based eating.
Want to Apply This Research?
- Track weekly plant-based meal count and health metrics (energy levels, digestion quality) on a 1-10 scale. This connects the abstract concept of ’eating more plants’ to concrete, measurable outcomes that users can see improving.
- Create a ‘Health Wins’ feature that shows users personalized health benefits they might experience from eating more plant-based meals, such as improved energy, better digestion, or clearer skin. Allow users to log how they feel after plant-based meals and celebrate improvements over time.
- Implement a 30-day flexitarian challenge with health-focused daily tips and progress tracking. Use push notifications highlighting health benefits (not environmental benefits) when users log plant-based meals. Track adoption intention weekly and correlate with actual meal logging to measure intention-to-behavior conversion.
This research measures stated intentions to adopt a flexitarian diet, not actual dietary behavior or health outcomes. Results are based on a UK online sample and may not apply to other populations or real-world settings. Before making significant dietary changes, consult with a healthcare provider or registered dietitian, especially if you have existing health conditions, take medications, or have nutritional concerns. This study should not be considered medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.