Junk Food Ads Increase Teenage Calorie Consumption

Liam Davenport

May 29, 2018

VIENNA — The more time young people spend watching commercial television, and consequently seeing adverts for foods high in salt, sugar and fat (HFSS), the more likely they are to consume junk food, with each extra advert linked to an extra 18,000 calories per year, survey results indicate.

The study of over 3300 teenagers, which was presented at the European Congress on Obesity in Vienna, showed that obese youngsters were significantly more likely to watch television, and that increased screen time was linked to an 80% increase in HFSS food consumption.

The report of the findings is published by the charity Cancer Research UK.

TV Ad Restrictions

The team says in a news release: "The food industry wouldn't pump hundreds of millions into advertising their products by creating catchy adverts if it didn't get people to eat more.

"Broadcast regulations in the UK haven't been updated since 2008, and our research shows that the current restrictions clearly aren't working."

They add: "With today's teens spending more time in front of screens than any other activity apart from sleeping, curbing exposure to junk food ads on streaming platforms as well as TV will be key to helping teens make healthy diet choices and reducing obesity rates."

Study presenter Gillian Rosenberg, PhD, from the Cancer Policy Research Centre at Cancer Research UK, told Medscape News UK that the study fills an "evidence gap" in showing that food marketing has an effect on childhood obesity.

She said that she therefore hopes that findings like these will inform the upcoming second version of the UK Government's Childhood Obesity plan for England.

Referring to the first version of the plan, published in 2016, Rosenberg said: "We were very disappointed that there wasn't junk food marking in obesity plan one, which is why we ramped up this type of research to provide the evidence for why it was important to be addressed."

Global Issue

However, she noted that "it's not just a UK issue, it's a global issue, and the more evidence we have that shows why this is an important issue and why measures will work, the better."

In her presentation, Rosenberg noted that rates of obesity increase during childhood, rising from one in five children starting primary school in England being overweight or obese to one in three children by the time they leave primary school, resulting in an additional 62,000 children becoming overweight or obese each year.

To examine the association between the marketing and consumption of HFSS and obesity levels in young people, the researchers initially developed a qualitative scoping survey to determine young people's perception of marketing and how this links to dietary choices.

They then used the findings to survey a national representative sample of 3348 people aged 11–19 years, gathering information on their age, gender, ethnicity, socioeconomic status, and food and drink consumption.

In addition, their television and online viewing habits, the HFSS adverts that they remembered, their brand awareness and their reactions to HFSS adverts were assessed.

They reported eating an average of almost 30 HFSS food items a week, accounting for 7000 calories per week, or 40% to 50% of the guideline total. This included 4.0 items of confectionary, 4.3 items of cakes and biscuits, and 2.5 sugary drinks, compared with just 7.6 items of fruit and 8.6 items of vegetables a week.

Overall, the participants watched an average of 21 hours of television a week. However, obese people spent more time watching television per week than other individuals, at an average of 26 hours (p<0.000). This equates to one extra advert per week.

Healthy, overweight and obese participants recalled seeing on average approximately six HFSS adverts per week, with obese people reporting seeing significantly more than those of normal weight. People from more deprived backgrounds were 1.4 times more likely to recall seeing HFSS adverts every day than those from higher socioeconomic groups.

"This, combined with their already greater risk of unhealthy weight outcomes, suggests that young people from deprived backgrounds would potentially have the most to gain from regulation designed to reduce junk food ad exposure," said lead researcher Jyotsna Vohra, PhD, head of the Cancer Policy Research Centre at Cancer Research UK, in the release.

The team also found that individuals who recalled seeing an HFSS advert every day were more than twice as likely to be obese.

Logistic regression analysis revealed that more time spent watching television was associated with a higher risk of HFSS food consumption, at an odds ratio of 1.8 (p=0.002).

Furthermore, recalling one extra HFSS advert over the average was associated with a significant increase in HFSS food consumption, at 350 calories per week or approximately 18,000 calories per year.

The researchers acknowledge, however, that their findings are observational, and that the self-report nature of the survey means that it is open to recall bias.

Rosenberg was confident however, that the results reflect the real world.

She pointed out that the study had a large sample size and that they "tested the questions beforehand with small focus groups to make sure that they were understood, but it's a limitation of the research and we could only go on the data that people are reporting".

Cause and Effect

Approached for comment, Anna Peeters, PhD, Deakin University, Melbourne, Australia, and Associate Director, Global Obesity Centre, World Health Organisation Collaborating Centre for Obesity Prevention, said that the study does not prove cause and effect.

"They've just asked the kids to report on what they've seen and what they eat. I don't think it means that what they've seen drove what they ate."

Peeters also questioned the need to carry out such research in the first place, given the current climate.

"There's this idea called the precautionary principle, which is what a lot of public health is based on now, which is saying we actually don't need to prove the causality," she said.

"Advertising drives people to buy things and eat things and consume things. That's why they do it. So let's stop worrying so much about whether we've proven all these causal links.

"As a precautionary principle, because it makes sense, we should just go and intervene and restrict marketing."

For Peeters, the most pernicious form of HFSS advertising to children is not on television, but via smartphone apps known as advogames. These, for example, encourage kids to download the app so they can have free food or drinks at a restaurant, and then show lots of HFSS-related adverts to users.

The consequence is that marketing companies, via apps and online advertising such as on Facebook, are blending advertising and entertainment into one package.

"They know who you are, they know what to advertise, so it's very sophisticated," she said. "Television is a really important area to act in because it's so visible, but it's a drop in the marketing ocean."

Peeters would therefore like to see strict limits on all HFSS advertising to children, and see that combined with measures such as bans on price promotions on HFSS products in supermarkets.

"There's so much that you can do as you start to really unpick how the food system drives purchasing," she said. "They drive it through price incentives, they drive it through placement, they drive it through promotion and marketing."

Co-author Dr M Bergo has received speaker fees from Baxter Medical and LEO Pharma; Dr L M Carlsson has received lecture fees from AstraZeneca, Johnson & Johnson and Merck Sharpe & Dohme. The other authors declare no conflicts of interest.

European Congress on Obesity 2018: Abstract O2.6. Presented 23 May.

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