A recent study published in the Health Promotion Journal of Australia has examined how adults respond to junk food advertisements and anti-junk food campaigns, focusing on how ad length and message framing affect cravings and intentions to eat junk food. The research highlights differences in effectiveness between normal-weight and overweight individuals.
The study involved 505 adults who were shown either a junk food or anti-junk food advertisement. Participants' cravings and intentions to consume junk food were measured before and after viewing the ads, using established questionnaires. The group was divided based on body mass index (BMI), allowing researchers to analyze responses according to weight status.
Junk food ads included brands such as McDonald's and Kentucky Fried Chicken, while anti-junk food ads either criticized unhealthy foods or promoted healthy eating. The duration of these advertisements varied between 15 seconds and 30 seconds.
Researchers found that exposure to a single junk food advertisement did not increase cravings or intentions to consume such foods among adults, regardless of their BMI classification. In some cases, normal-BMI participants experienced a slight reduction in craving after watching a longer (30-second) junk-food advertisement. This finding is consistent with earlier studies that suggest short-term exposure may not significantly impact adult behavior.
On the other hand, certain anti-junk food advertisements led to reduced cravings and lower intentions to eat junk foods. Notably, shorter (15-second) critical anti-junk food messages were particularly effective at reducing cravings and consumption intentions among normal-BMI individuals. For those with higher BMI, shorter encouraging messages—those promoting healthy eating rather than criticizing junk food—were more effective at lowering cravings.
Both groups responded similarly when exposed to longer (30-second) anti-junk-food advertisements, which generally resulted in decreased intention to consume junk foods.
The study also observed that self-control traits like restraint played a role: people with lower restraint reported stronger cravings when exposed to junk food ads.
Researchers caution that their findings are limited by several factors: participants viewed each ad only once; results reflect short-term changes in self-reported craving rather than actual long-term behavior; and the controlled viewing context does not represent real-world media environments where people encounter repeated advertising exposures across multiple platforms.
The authors note: "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." They recommend further research into how repeated exposure might shape habits over time.
