Well if you wanted a ban on advertising sugary cereal to kids, you would have to pass the "Central Hudson" test. You would have to prove a compelling government interest to ban the ads to children. The ADA chief medical scientist has already said there is no conclusive proof that sugary food causes diabetes. Also I don't know if you've seen any kids cereal commercials recently, but they're not making deceptive claims (like "eating this cereal will make you healthier").

http://law2.umkc.edu/faculty/projects/ftrials/conlaw/commerc...