The food industry is spending millions of dollars on slick digital marketing campaigns promoting fatty and sugary products to teenagers and children on the Internet, on cell phones and even inside video games -- often without the knowledge of parents.
It used to be that food companies reached children mainly through television commercials broadcast during cartoon programs.
But now companies maintain flashy Internet sites with eye-catching graphics that allow kids and teens to interact with brand mascots, create their own characters, and even make their own ads and send them to friends.
Watch "World News" this evening for a full report on the eye-catching marketing of foods to children.
The effort extends to social-networking sites such as Twitter and Facebook, where companies have created fan pages and posted applications promoting their drinks and candies. On YouTube, kids can watch viral videos from Burger King and other food giants.
The marketing gurus behind Fanta soda have even developed technology that teens can download on their cell phones, which allows them to send audio messages to each other at high frequencies, sounds that adults over 25 cannot hear.
This digital marketing, critics say, flies under the radar of most parents -- even those who consider themselves vigilant about what their children watch and eat. Indeed, some parents told ABC News they have no idea such marketing even exists.
"I was very unaware of the fact that there were these commercials that were popping up on the Internet," said Alison Paul of Windham, N.H., a single mom whose son has struggled mightily with his weight.
"It does not make me happy to know that I'm working so hard to try and give my son a healthy life, and when the outside world is working against me, it's frustrating," she said.
Paul's son, Eli, 13, added, "I have seen them in video games and I've seen them on TV and on Facebook. It's annoying. You know, you don't want this big burger flashing in your face."
Jeffrey Chester and Kathryn Montgomery, themselves parents of a teenage girl, have been researching what's called "360 Marketing." Chester runs a watchdog group called the Center for Digital Democracy in Washington, D.C.; Montgomery is a professor of Communication at American University.
"The production values now on these sites are very professional -- full-motion video, often 3-D quality, terrific sound and high-quality animation. So this is not just an old-fashioned Web site; this is a really immersive experience that we're allowing kids to enter," Chester said.
"And in many ways it's really like becoming part of the commercial," his wife added.
At www.reesespuffs.com, kids can create their own avatars, dance to the Reese's Puffs rap and then share their dance with friends.
Like Reese's Puffs, Trix cereal is owned by General Mills and operates a site at www.sillyrabbit.com that goes far beyond its old television spot featuring a bouncing rabbit and the slogan, "Trix Are for Kids!" Children can enter a colorful "Trix World" where they can bowl at "Fruitalicious Lanes" or explore a "Rabbitropolis" that has a movie theater showing "Trix Toons."