NEW HAVEN: Fast food advertising targeting teens via mobile devices and social media has grown exponentially, while the number of fast food TV ads viewed by younger children has declined, according to a new report.

The Yale Rudd Center for Food Policy & Obesity carried out a follow-up to its 2010 study Fast Food FACTS with an analysis of the marketing and advertising practices of 18 fast food restaurant chains, as well as the nutritional quality of their menus.

It found that 6bn fast food ads appeared on Facebook in 2012, which amounted to 19% of all fast food display advertising. A majority of Dunkin' Donuts' and Wendy's ads appeared on the social networking site.

In addition, smartphone apps were offering games and interactive features such as order functions and special offers.

But TV advertising viewed by children aged 6 to 11 had declined by 10% between 2010 and 2012 to 3.2 ads per day, as McDonald's and Burger King reduced their TV advertising. And the number seen by pre-school children remained steady on 2.8 ads per day. Even so, three-fifths of fast food restaurants had increased TV advertising to older children.

"Most fast food restaurants stepped up advertising to children and teens," said Jennifer Harris, the Rudd Center's director of marketing initiatives and lead author of the report.

"Most advertising promotes unhealthy regular menu items and often takes unfair advantage of young people's vulnerability to marketing, making it even tougher for parents to raise healthy children," she added in remarks reported by Adweek.

For example, the report said McDonald's had increased the number of display ads for its Happy Meals by 63% to 31m ads monthly and claimed three quarters of these appeared on children's websites, such as Nick.com, Roblox.com, and CartoonNetwork.com.

The report also highlighted a focus by fast food restaurants on black and Hispanic youth, groups which, it noted, were at a relatively higher risk of obesity and related diseases.

Overall, fast food adspend on Spanish-language TV had increased 8%, but KFC and Burger King had upped their spends here by 35% to 41% while at the same time reducing English-language advertising.

Data sourced from Yale Rudd Center, Advertising Age; additional content by Warc staff