Short anti-junk food ads cut adult cravings

A single junk food ad may not sway adults, but the right 15-second health message can. Researchers reveal how ad length and framing shape cravings differently for normal-weight and overweight viewers, offering new clues for smarter public health campaigns.

Study: Length and Framing of Anti-Junk Food Ads Impact Inclinations to Consume Junk Food Among Normal Weight, Overweight, and Adults With Obesity. Image credit: Roman Samborskyi/Shutterstock.com

Junk food advertising is highly prevalent across media platforms and has been widely associated with increased short-term consumption, particularly in children. A recent paper published in Health Promotion Journal of Australia examined whether junk food advertisements actually increase cravings in adults, and whether anti-junk food campaigns can counter them depending on how long they run and how their message is framed.

Do anti-junk campaigns work better?

Junk food is energy-dense, nutrient-poor food. Its advertising is largely unrestricted in Australia, despite its known association with poor eating habits and health risks. Anti-junk food advertising has been shown to reduce cravings for and intentions to consume junk food among adults.

The current study examined the risks and benefits of anti-junk food advertising, using BMI as a classification criterion. A high BMI may reflect greater vulnerability to unhealthy eating patterns and has been suggested in prior research to indicate possible susceptibility to respond to advertisements around junk food, for or against.

The length of the advertisement is another factor. While longer advertisements may be associated with greater message recall, shorter ones are usually preferred because they take less effort and time to process. Finally, the way the anti-junk food message is framed affects the viewer’s response: junk food advertisements praise junk food, but anti-junk food advertisements may criticize it or promote healthy food.

However, the relative effectiveness of these two approaches in reducing short-term junk food consumption inclinations remains unclear. This study replicates earlier research and extends it to an unexplored segment of adult consumers.

Comparing junk food and anti-junk food ads

The study included 505 adults who viewed a randomly chosen junk food or anti-junk food advertisement. They were first asked to estimate their junk food cravings and intentions to consume junk food, using the Food Craving Questionnaire.

Randomly assigned participants viewed one of the following conditions:

• a neutral advertisement (one of two 15-second advertisements not related to food)
• a 30-second critical anti-junk food advertisement
• a 15-second critically framed anti-junk food advertisement
• a 15-second positively framed anti-junk food advertisement
• a 30-second junk food advertisement
• a 15-second junk food advertisement

The junk food advertisements were one of eleven unique, randomly selected advertisements. They included brands like McDonald’s and Kentucky Fried Chicken.

Anti-junk food advertisements comprised three videos graphically showing cancer associated with junk food. The 30-second and one of the 15-second advertisements ended with a warning against junk food. The third ended by promoting healthy food as a way to reduce junk food.

Viewers reported what they felt immediately after viewing one of eleven randomly selected unique junk food advertisements in terms of their immediate craving and what they intended to consume. These were classified as 15-second and 30-second advertisements.

After viewing the advertisements, they reported their craving and consumption intentions, as well as self-control and impulsivity measures. Responses were stratified by normal vs excessive BMI.

Junk food ads fail to raise cravings

The mean participant age was 38 years, with 78 % being Caucasian and 11 % Asian. The mean BMI was above the overweight threshold, at ~27.

In both groups, viewing junk food advertisements did not increase craving, nor did the viewers intend to consume such food. In the normal-BMI group, one 30-second junk-food advertisement was associated with a modest reduction in craving, but no junk-food condition increased consumption intentions. Cravings were not increased even when the junk food advertised matched that currently consumed. Even in a subgroup exposed to advertisements featuring junk food, they reported no increase in enjoyment, cravings, or consumption intentions. This aligns with prior research findings.

In contrast, some neutral and anti-junk food advertisements were associated with reduced craving, and only certain anti-junk formats were associated with a lower intention to consume junk foods.

Among participants with normal BMI, shorter (15-second) anti-junk food advertisements that critically framed junk food showed particularly strong reductions in craving and consumption intentions, while the 30-second anti-junk advertisement also reduced both outcomes. Consumption intentions decreased with the critical anti-junk advertisements but not with the neutral, junk-food, or encouraging anti-junk-food advertisements.

In the high-BMI group, junk food cravings decreased after viewing the neutral or anti-junk food advertisements, except for the short critical one. Thus, individuals with normal BMI were more likely to respond to the critical advertisement.

In contrast, high-BMI viewers showed greater reductions in craving following the short, encouraging advertisement, while both groups responded similarly to the longer anti-junk-food advertisement. Consumption intentions were reduced most consistently after viewing the longer anti-junk advertisement in this group, with some shorter-format effects not remaining statistically significant under stricter correction thresholds.

Unhealthy eating was correlated with lower restraint and impulsivity, but was largely unchanged by viewing advertisements. The only exception suggests that lower restraint is associated with stronger craving when exposed to junk food.

Despite the small number of participants, the researchers identified differences in responses to the shorter, encouraging vs. critical anti-junk food advertisements between the normal- and high-BMI groups. No such difference was observed with the longer advertisements. This is construed as a possible indicator that the 15-second advertisements may be more efficient in targeting two different groups within the same time interval.

These findings were based on a single exposure to various types of junk food and anti-junk food advertisements. The authors comment on the probable higher efficacy of multiple exposures to junk food advertising, both in building brand loyalty and in increasing long-term junk food consumption.

Such advertisements also build a culture where junk food is seen as a normal part of the human diet, especially affecting the health of children, teenagers, and susceptible adults. Future research should build on the actual effects of multiple exposures.

Limitations

The study has several important limitations. Participants were exposed to each advertisement only once, meaning the findings cannot capture the potential cumulative effects of repeated exposure over time. The research also measured only short-term changes in craving and consumption intentions, rather than longer-term behavioral outcomes. All outcomes were based on self-reported measures, which may be subject to bias. In addition, the experiment was conducted within a single, controlled viewing context, which does not fully reflect the multiple, dynamic media platforms through which junk food advertising is commonly delivered in real-world settings.

Smarter ad design could improve public health

With a single exposure, random junk-food advertisements did not immediately increase craving among adults. Some anti-junk food advertisements were associated with reductions in craving and, in several conditions, with reductions in consumption intentions, irrespective of BMI classification. However, shorter anti-junk food advertisements that critically framed junk food were more effective among normal-BMI participants, whereas shorter anti-junk food advertisements encouraging healthy food elicited better responses among high-BMI individuals.

These nuances are important for maximising the effectiveness of anti-junk food advertisements in different contexts.

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