In 2016, two UN human rights experts called upon schools to ban advertising, promotion and sponsorship of unhealthy foods in schools, which they said was contributing towards the obesity of young people.
Such commercial messages, they said, have the potential to shape children’s long-term consumer and financial behaviour – and what’s more, they are growing in number and reach.
Now, a world-first study has found that junk food ads lead to overeating capable of driving unhealthy weight gain in children.
The study, published in the International Journal of Behavioural Nutrition and Physical Activity, shows that children eat more food after watching unhealthy food advertising and don’t compensate by eating less at later meals.
On average, the daily food intake of children in the study increased by almost 50 calories after watching food advertising; an amount that over time would lead them to becoming overweight.
Lead author Jenny Norman, a PhD student at the University of Wollongong’s (UOW) Early Start and School of Health and Society, said previous studies have shown that food advertising increases children’s immediate food consumption, but this was the first to show that this could lead to calorie imbalance.
“This study shows food marketing can directly influence calorie imbalances capable of driving excess weight gain in children,” Norman said.
“We know when children watch food advertising they eat more at a snack afterwards. What hasn’t been shown before is whether that short-term increase is compensated for at later meals, and that’s what we measured in our study.”
The study involved 160 children between the ages of seven and 12, and took place over six days at a school holiday camp. On three of the days the children watched food advertising – a television cartoon and, for some children, an online game as well. On the other three days, they watched non-food advertising.
The researchers measured the children’s food intake at a snack soon after watching advertising as well as at a later meal. On food advertising days the children left camp with an average positive energy imbalance of almost 50 calories.
Previous studies have shown that an energy imbalance of between 50 and 70 calories is enough to drive unhealthy weight gain in children.
Exposure to both online and television advertising exerted a stronger influence than exposure to television advertising alone, the researchers found.
“Exposure to food advertising from multiple media is part of children's daily life. Children are avid users of modern technology and it is not unusual for children to be watching TV while playing online,” Norman said.
“We captured our results in an experimental setting where children were exposed to a limited and controlled amount of advertising. In the real-world they are exposed to many more unhealthy food messages over the course of the day, and could be stimulated to eat unhealthy foods much more than we saw in our study.”