Public health campaigns often rely on lengthy warnings about unhealthy food. A new study suggests shorter messages may sometimes work better.
Researchers at Edith Cowan University in Australia found that brief advertisements encouraging healthy choices reduced immediate cravings and intentions to consume junk food. In some cases, 15-second ads were more effective than traditional 30-second versions.
The study, published in the Health Promotion Journal of Australia, involved 505 Australian adults who were randomly shown either a junk food advertisement or an anti-junk food advertisement. Participants then reported their immediate cravings and intentions to consume unhealthy foods.
“Junk food advertising in Australia remains largely unregulated, despite significant public health concern,” said Dr. Ross Hollett, who led the study. “We wanted to understand what actually happens in the moments after adults see junk food and anti-junk food ads.”
Surprisingly, exposure to a single junk food advertisement did not significantly increase cravings or consumption intentions, even when participants were shown foods they reported enjoying.
In contrast, anti-junk food advertisements reduced cravings and intentions across participants. The effect depended on both the length and framing of the message.
For participants within the normal BMI range of 18.5–25, a 15-second anti-junk food advertisement had a stronger immediate impact than a 30-second version.
“For some viewers, a short, sharp message may have more immediate impact than a longer ad,” Hollett said.
Among participants classified as overweight or living with obesity, a 15-second advertisement that encouraged healthy food choices was more effective than one that criticized junk food.
“This suggests positively framed health messages may resonate more strongly with audiences carrying greater health risks,” Hollett said.
The study focused on immediate reactions rather than long-term behavior change. Participants self-reported cravings and intentions immediately after viewing the advertisements. The research did not measure whether participants ultimately changed their eating habits.
Still, the findings offer insight into how quickly messaging can influence food-related decision-making.
“If we’re investing in public health campaigns, it’s important to know not just whether they work, but for whom and under what conditions,” Hollett said.
The researchers suggest that increasing the frequency of brief, positively framed health messages could help support healthier choices, though they emphasize that advertising is only one factor in a much larger food environment.
This research was supported by Edith Cowan University. The study also received a small departmental contribution. One researcher was supported by a Stan Perron Foundation People Fellowship and an Edith Cowan University Vice Chancellor’s Professorial Fellowship. Open access publishing was facilitated by Edith Cowan University through a Wiley agreement via the Council of Australasian University Librarians.