The impact of food advertising on children's daily energy intake: does it differ by advertising content, format, or participant characteristics? A cross-over randomised controlled trial.

Exposure to audiovisual advertising for unhealthy food products increases children's immediate food consumption and effects may persist to subsequent meals. The impacts of food advertising that is brand-only or in other formats is unknown. This study aimed to quantify the impact of unhealthy food advertising on children's immediate and later intake; and assess differences in impacts for different advertisement content (brand-only vs. product), format (audiovisual vs. visual vs. audio vs. static), or sociodemographic characteristics. A pre-registered cross-over randomised controlled trial was conducted in schools in Merseyside, UK. Across two sessions, child participants (n = 240, 7-15 years, M = 11.0 ± 2.0) were exposed to 5-min of unhealthy food (intervention condition) and non-food (control condition) advertisements that were brand-only or product-based and in one of four media formats. Measurements included ad libitum intake of snacks and lunch, and height and weight. Area-level socioeconomic deprivation was calculated using home postcode. Data were analysed using linear mixed models. After food advertising (vs non-food), children consumed more energy at snack (+58.73 kcal; p < .001) and lunch (+72.93 kcal; p < .001). There was no statistically significant difference in effects by advertisement content, media format, or deprivation. This is the first study to show that brand-only food advertisements increase children's food intake, with effects not statistically different to that for product ads, and that impact is similar across advertising formats. Findings are theoretically informative and have implications for the design of restrictive food marketing policies in the UK and globally.