Katie Couric's Notebook: Food Addiction

For decades, Lay's potato chip ads taunted us with the slogan "Bet you can't eat just one."

Turns out they were right.

A new study has found that junk food isn't just tempting, it's actually addictive.

Scientists at the Scripps Research Institute served one group of rats a steady diet of nutritious food. The other group got unlimited quantities of high-fat goodies like cheesecake and bacon.

No surprise, the rats fed junk food became obese and lethargic. But here's the shocker: when the researchers replaced the junk food with healthy food, the rats wouldn't eat at all. They opted to starve instead.

The authors say it's just like drug addiction, a concept former FDA Commissioner David Kessler explained to me in a recent interview. His book ,The End of Overeating, shows how the food industry -- and our brain chemistry -- work to keep us all hooked.

It's a tough battle between self control and out of control eating, so just say no and send a message to these companies that snack is whack. 

That's a page from my notebook.

I'm Katie Couric, CBS News.