Does knowledge change behaviour?
Lessons from calorie labelling
Last week, a new study on calorie labelling in England revealed an important finding: while the policy increased awareness of calorie content, it didn’t lead to measurable reductions in caloric intake. This result has reignited debate over the effectiveness of knowledge-based interventions in changing behaviour.
On the surface, this might seem like proof that knowledge fails to drive meaningful change but behaviour is rarely that simple. Knowledge is an essential ingredient, but rarely enough on its own. For it to translate into action, it must work within a supportive system—one that considers context, competing motivations, and structural barriers. This study offers critical lessons for policymakers and behavioural scientists alike, prompting us to ask a better question: how can we use knowledge more effectively to support real-world behaviour change?
The study at a glance
Published this week, the study examined the impact of mandatory calorie labelling in England’s out-of-home food sector, introduced in April 2022. Researchers collected data from over 6,500 customers across 330 food outlets, comparing caloric consumption before and after the policy was implemented.
The findings revealed:
Increased awareness: More customers noticed calorie labels and could estimate caloric content more accurately post-implementation.
No significant behavioural change: Calorie consumption remained stable, with average intake slightly increasing from 1,000 to 1,080 calories per meal—a change not statistically significant.
The researchers concluded that while calorie labelling may increase awareness, it doesn’t directly reduce caloric intake.
What knowledge can (and can’t) do
Knowledge is the foundation of behaviour change, but it is rarely sufficient on its own. Awareness sparks the process, but meaningful change requires more than information—it needs supportive systems to turn knowledge into action.
A common reaction to studies like this is to dismiss knowledge-based interventions as ineffective. The results—no significant change in caloric intake—might seem to confirm this view. However, such a conclusion oversimplifies the reality that behaviour change is rarely immediate or linear. Instead, it often begins with awareness.
The study’s finding that calorie labelling increased awareness shows that information isn’t irrelevant—it’s a stepping stone. Noticing and understanding calorie counts might not lead to immediate behavioural shifts, but it opens the door for complementary strategies. For example, pairing labels with structural interventions like default healthy options or price incentives could nudge people toward healthier decisions over time. Behavioural change often requires layers, and labelling may be one small but necessary piece of a bigger puzzle.
Frameworks like the COM-B model and the Transtheoretical Model position awareness as an early stage in the behaviour change process. For example, people need to recognise that calorie counts are relevant to their decisions before they can integrate this knowledge into actions. By increasing awareness, calorie labelling lays the groundwork for other interventions (e.g., defaults or incentives) to drive behavioural shifts.
Immediate behaviour changes aren’t always realistic for interventions like calorie labelling, which rely on habit formation and repeated exposure. Over time, greater awareness could contribute to a gradual shift in norms or decision patterns.
While the study supports the idea that awareness is important, it doesn’t inherently validate calorie labelling as a behaviour change tool. People may notice calorie labels but still prioritise other goals—such as indulgence or social bonding—over health-related decisions. Without addressing contextual factors, labelling alone is unlikely to have a substantial impact.
It’s also worth considering the potential ceiling for awareness. Some groups, like frequent diners or health-conscious individuals, might already engage with calorie information, limiting the marginal benefit of labelling. For others, barriers beyond awareness—such as affordability or taste preferences—may prevent them from acting on the information.
The key takeaway is that awareness isn’t sufficient, but it’s not irrelevant either. It is a critical early step that requires complementary interventions to translate knowledge into sustained behaviour change.
Why calorie labels alone aren’t enough
Calorie labelling increases awareness, but without alignment with structural and contextual factors, it’s unlikely to drive consistent behavioural change.
The study revealed an important finding: while calorie labelling increased awareness, it didn’t result in reduced caloric intake. This gap—between noticing calorie information and acting on it—highlights the limits of knowledge-based interventions in driving immediate behaviour change. Several factors could explain this lack of impact, but the study leaves them unexplored. For instance:
Competing priorities: People may notice calorie labels but choose to prioritise other factors, such as indulgence, particularly during special occasions, when health goals might feel less relevant, or value for money, especially in a cost-of-living crisis, which might make calorie-dense meals feel like a better deal.
Contextual barriers: The dining environment plays a significant role in whether calorie information is used. Questions the study doesn’t answer include:
How often do social settings, like group meals, shift attention away from individual health goals and toward the dynamics of the occasion?
Are rushed or stressful contexts—such as grabbing lunch during a busy workday—less conducive to engaging with calorie information?
Structural constraints: Even with awareness, external factors might limit diners’ ability to act on calorie information. These could include limited availability of appealing, lower-calorie options on menus or affordability constraints, which make calorie-conscious choices less feasible for some diners.
The study provides important insights into awareness but doesn’t investigate these contextual or structural factors. As a result, it’s premature to conclude that calorie labelling doesn’t work. Instead, the findings suggest that labelling alone isn’t enough—it must be part of a broader strategy that addresses the complex realities of real-world decision-making.
The role of context in decision-making
Behaviour is shaped by context. Social, cultural, and economic factors often take precedence over health goals, determining whether calorie labels are noticed, acted on, or ignored.
Food choices don’t happen in a vacuum. They’re shaped by the environment in which decisions are made, and these contexts can significantly influence how calorie information is perceived and used. Yet, the study doesn’t explore these critical factors, making it difficult to draw firm conclusions about why labelling had no measurable impact on caloric intake.
Take social settings, for example. Dining with friends or family may shift focus away from individual health goals and toward shared norms or the enjoyment of the occasion. In such contexts, the immediate goal isn’t eating fewer calories—it’s connecting with others or celebrating, which might deprioritise calorie information.
Economic considerations also play a role. During times of financial constraint, people might prioritise value for money over calorie content, favouring richer, more indulgent meals that feel like a better deal. This is especially likely in out-of-home dining, where indulgence is often perceived as part of the experience.
The study doesn’t provide data on these contexts which leaves critical gaps in our understanding of how and when calorie labels are effective. What we can infer is that food choices are rarely about health alone. Decisions often reflect competing priorities, shaped by cultural norms, social dynamics, and economic pressures. Far from being "failures" to act on calorie information, these choices are often rational responses to the realities of the moment.
The role of context in decision-making
Food choices are shaped by context. Social, cultural, and economic factors often outweigh calorie considerations, making labelling less relevant in many real-world situations.
The study found no significant impact of calorie labels on caloric intake, but it doesn’t account for the contexts in which decisions are made. These unmeasured factors likely explain why calorie labelling didn’t drive behavioural change.
Key contextual influences include:
Social settings: Dining with others often shifts attention away from calorie labels and toward the social dynamics of the occasion. In these moments, food choices are driven by hedonic value—prioritising pleasure, indulgence, or connection—rather than health goals.
Consumption occasion: The purpose of eating out matters. A celebratory meal encourages indulgence, often accompanied by moral licensing (“I’ve earned this”). In contrast, a solo lunch on a workday might make calorie-conscious decisions more likely.
Economic pressures: During times of financial constraint, diners might seek meals that feel more rewarding for their cost. Calorie-dense options often deliver higher perceived value, both economically and hedonically, compared to lighter alternatives.
Frequency of dining out: For those who eat out rarely, the experience may feel like a treat, where indulgence becomes the primary goal. Regular diners, on the other hand, might approach the decision differently, with less emphasis on indulgence and more focus on habit or convenience.
Everyday habits: In rushed or stressful situations—such as grabbing a meal during a busy workday—decision-making is often automatic. Familiarity and convenience take precedence over deliberative calorie considerations, reducing the impact of labelling.
In the context of market research, audience characteristics and consumption occasions are often central to understanding behaviour. These approaches recognise that motivations for food choices vary significantly depending on context. Behavioural science and behaviour change interventions often overlook this segmentation, assuming universal responses to interventions like calorie labelling.
Food choices reflect competing priorities, not failures to act on information. Whether it’s enjoying a rare celebration, seeking value for money, or simplifying a busy day, decisions often align with immediate goals rather than abstract health concerns. Without addressing these contextual drivers, it’s premature to conclude that calorie labelling doesn’t work. The effectiveness of any intervention depends on how well it aligns with the lived realities of decision-making environments.
What else could work as an intervention?
Calorie labelling may have its limitations, but it also opens the door for ideas that complement awareness with thoughtful design. One such idea is sorting menu options by calorie count—from lightest to heaviest. This concept aims to guide healthier choices by reshaping the decision-making environment, reducing cognitive load, and encouraging moderation without restricting autonomy.
This idea builds on key behavioural principles:
Cognitive ease: Listing options by calorie count reduces the mental effort required to compare choices. Instead of scanning the menu for the “healthiest” option, diners can naturally gravitate toward items at the top. This heuristic simplifies decision-making without demanding active calculation.
Choice defaults: Organising menus this way positions lower-calorie items as the "default" or first-choice options, leveraging the status quo bias. Diners are more likely to stick with the first items they see rather than scrolling or searching extensively.
Anchoring: Starting with lighter options creates an anchor for what’s perceived as “normal” or appropriate calorie levels. Higher-calorie items further down the list may feel excessive or indulgent by comparison, encouraging moderation.
Reduced decision fatigue: Faced with many options, diners often feel overwhelmed and default to habitual or impulsive choices. A calorie-sorted menu streamlines the process, making healthier options easier to access while preserving autonomy.
To put this idea into practice, menus—both physical and digital—could be redesigned to subtly guide choices while preserving diners’ autonomy:
Digital menus: Online ordering platforms could automatically sort items by calorie count as the default, with a toggle option allowing users to reorder based on preferences like price or popularity.
Physical menus: Printed menus could list items by calorie count within sections, particularly in fast-casual dining settings where efficiency is key.
Layered interventions: Combining calorie-sorted menus with labelling provides both transparency and an intuitive nudge, creating a more comprehensive approach to guiding decisions.
However, even thoughtful design changes come with potential risks. While calorie-sorted menus align with key behavioural principles, there is a possibility they could backfire if diners perceive them as overly directive or manipulative. Transparency is essential to mitigate this risk—explaining the rationale behind the menu design, such as “Items are listed by calorie content for convenience,” can help maintain trust and minimise resistance.
Final thoughts
The question of whether knowledge changes behaviour is far more complex than it appears. While the findings of the calorie labelling study might tempt us to dismiss awareness-based interventions as ineffective, that would be an oversimplification. Knowledge plays an essential role in behaviour change—it’s the foundation for awareness, which, in turn, lays the groundwork for action. However, knowledge alone is rarely enough. Behaviour is shaped by context, competing priorities, and structural barriers that make it difficult for awareness to translate into healthier choices.
Interventions like calorie labelling can increase awareness, but their impact depends on how well they integrate into the realities of decision-making environments. Context matters, whether it’s a celebratory meal that prioritises indulgence, the economic pressures that make value for money a key driver, or the habitual choices that emerge in rushed or stressful situations. These influences must be accounted for if we want knowledge to translate into meaningful change.
Moving forward, solutions that combine awareness with thoughtful design—like sorting menus by calorie count—could complement labelling strategies and guide healthier decisions more intuitively. By pairing knowledge with behavioural principles like choice architecture, we can create interventions that align better with how decisions are made in real life.
This is only one piece of the puzzle. In a follow-up article, I’ll explore how the Behaviour Change Wheel (BCW) framework can provide a structured lens for designing more comprehensive and impactful interventions. Stay tuned as we continue to unpack the nuances of behaviour change and how to make it work in practice.
Polden, M., Jones, A., Essman, M., Adams, J., Bishop, T. R., Burgoine, T., ... & Robinson, E. (2024). Evaluating the association between the introduction of mandatory calorie labelling and energy consumed using observational data from the out-of-home food sector in England. Nature Human Behaviour, 1-10. (Open access)