Some advertising has been shown to affect kids' well-being and lead to unhealthy choices. But even though health problems such as childhood obesity, tobacco use, and underage drinking affect large numbers of kids, it's difficult to prove that they're caused by the advertising of unhealthy products.
The harm lies in the persuasive techniques advertisers use to influence kids. Kids are impressionable, and marketing takes advantage of sophisticated devices -- demographic data, psychology, developmental characteristics, and behavior traits -- to determine the most effective ways to influence them.