Familiarity with junk-food ads linked with obesity in young people
Young people who watch one extra junk-food advert a week (over the average of six) consume an additional 350 calories in foods high in salt, sugar, and fat (HFSS) every week (18,000 each year).
A large study conducted by Cancer Research UK is one of the first to look at online TV viewing in such a systematic fashion, and adds to the growing evidence that TV and streaming adverts can influence young people's unhealthy diet. Although the causes of obesity are complex, previous research has found strong links between increases in advertising for fast foods and rates of childhood overweight and obesity.
The study investigated the link between HFSS food marketing and consumption behaviours among teens in the UK. A qualitative scoping study explored young people's perceptions of marketing, and the mechanisms linking this with dietary choices, then a national sample of 3348 young people aged 11– 19 years were studied to further examine the link between marketing and high calorie diets.
On average, young people watched 21 hours of television a week with adverts, with just over half of this time viewed on streaming platforms. However, obese teens watched significantly more television-around 26 hours (equivalent to one extra advert a week). Participants reported eating almost 30 HFSS food items every week (equivalent to 40-50% of this age group's recommended total calorie intake), but only 16 portions of fruit or vegetables. Overall, results showed that the more junk food ads young people watched, the more HFSS foods they were eating.
The researchers found that greater familiarity with fast-food marketing was associated with eating more foods HFSS and increased weight, regardless of age and gender. Those from a more deprived background were more likely to recall HFSS adverts than those who were not.
The authors concluded, "Broadcast regulations in the UK have not been updated since 2008, and our research shows that the current restrictions clearly are not working. 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."
The authors acknowledge that their findings show observational differences rather than evidence of cause and effect. They note some limitations, including that the study is based on a self-reported survey of viewing and eating habits which can lead to problems of recall and could have affected the results.
- Levels of obesity in teens aged between 12 and 19 years tripled in the USA (5% to 17.6%) between 1980 and 2008. Similarly, in England, around a fifth of children in the last year of primary school (aged 10 to 11), and one in every four adults is obese. Obese children are around five times more likely to become obese adults with a much higher risk of health problems including 13 obesity-related cancers, type 2 diabetes, and cardiovascular disease.
- In 2017, a report by the Obesity Health Alliance found that junk food companies in the UK spend almost 30 times more on advertising (£143 million) than the Government does on healthy eating campaigns (£5 million).
The study confirmed that junk food marketing is associated with obesity in young people of all ages, thus increasing cancer risk. 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.
The report Under Pressure - A Study of Junk Food Marketing and Young People's Diets is published by Cancer Research UK. Research presented at the European Congress on Obesity 2018 (oral presentation 02.6).