Five minutes exposure to junk food marketing results in children consuming 130 kcals more per day, trial finds

Exposure to junk food advertisements (relative to non-food) results in children and adolescents consuming significantly more calories during the day, regardless of the type of media advertising, according to a randomized crossover trial being presented at the European Congress on Obesity (ECO) in Malaga, Spain (11–14 May).

The study found that 7–15 year-olds exposed to just five minutes of adverts for foods high in saturated fats, sugar, and/or salt (HFSS) consumed on average 130 kcals per day extra, which is equivalent to the calories in two slices of bread.

The timely research is presented as many countries across Europe and globally are considering implementing curbs on unhealthy food advertising to tackle rising childhood obesity levels.

“Our findings offer crucial novel information on the extent, nature, and impact of unhealthy food marketing via different types of media on young people’s eating behavior,” said lead author Professor Emma Boyland from the University of Liverpool in the UK.

“Even short exposure to the marketing of foods high in fat, salt, and sugar can drive excess calorie consumption and potentially weight gain, particularly in young people who are more susceptible to advertising and whose eating patterns influence their lifelong health.”

The causes of obesity are complex and influenced by many factors. While research has highlighted connections between product-based advertising of foods HFSS in audiovisual media on children’s immediate and later consumption, little is known about the impact of other forms of media including brand-only (i.e. ads only featuring branding elements such as logos, but no food or beverage products) or audio advertisements (e.g., podcasts, radio) in shaping eating patterns.

It is also unclear whether food advertising effects differ by individuals’ sociodemographic characteristics, and therefore how it may contribute to health inequalities.

To explore this further, researchers conducted a randomized crossover trial to quantify the impact of HFSS food (vs. non-food) ad exposure on children’s immediate and later intake, and to assess whether this was moderated by either advertisement content (brand-only vs. product), media type (audio-visual [e.g., TV] vs. visual [some social media posts] vs. audio [podcasts] vs. static [paper billboards]), or sociodemographic characteristics.

In total, 240 volunteers between the ages of 7 and 15 years from schools across Merseyside, UK, participated in the study. On two different occasions, participants were exposed to five minutes of HFSS food and then non-food advertisements that were either brand-only or product-based through one of the four different medias.

Researchers then measured children’s subsequent ad libitum intake of snack and lunch foods along with their height and weight to calculate body mass index (BMI). Home postcodes were used to calculate area-level socioeconomic status (SES) using the 2019 English Index of Multiple Deprivation.

The analysis found that following exposure to HFSS food ads, children consumed more snacks (+58.4 kcals), more lunch (+72.5 kcals), and more food overall (snack and lunch combined (+130.90 kcals) than after exposure to non-food ads.

Interestingly, advertisement content did not moderate this effect, such that brand-only ads were as effective as product ads in increasing intake.

While neither the type of media (i.e., audio-visual, visual, audio, static image) nor socioeconomic status moderated children’s intake, the researchers found that for every standardized unit increase in BMI score (zBMI, adjusted for a child’s age and sex), children consumed an additional 17 kcal overall.

According to Professor Boyland, “Our results show that unhealthy food marketing leads to sustained increases in caloric intake in young people at a level sufficient to drive weight gain over time. This study is the first to demonstrate that brand-only food ads, for which there is currently no restrictive advertising policy globally, increase children’s food intake. This new knowledge will help in the design of urgent restrictive food marketing policies that can protect children’s health.”

Provided by
European Association for the Study of Obesity