I had cleaned up a kid's vomit before, so that wasn't the shock of my Saturday night a few weeks ago.

The shock occurred when we deviated from our tried-and-true plan. Normally when my father and I baby-sit my niece and nephew so that my brother and his wife can go out to eat and catch an early movie, we play at Pop-Pop's until the kids get hungry, and then he takes them out to eat at Arby's or McDonald's.

This time, however, Luke began vomiting just as they were preparing to leave. Since I had already eaten a salad, two Boca Burgers, and three broiled eggplant sandwiches (absolutely delicious and only 125 calories each!), I offered to take Kobi out and bring back something for my father.

Kobi's nearly nine, pretty sharp, and knows how I feel about fast food, so she was not only surprised when I offered, but also downright stupefied when I allowed her to choose the site and her foods. She picked Wendy's because she said she had only been there once, and then asked with clear doubt in her voice, "Could I have a Frosty?"

Now I was young once and for years considered a Frosty-like milk shake I had as an 11 year old while watching the Phillies play the Cardinals at Veterans Stadium to be one of the great culinary experiences of my life, so I agreed with one stipulation: that if she felt full, she'd save some of the Frosty for her late-night snack.

She agreed and she did save about half of the Frosty for later but that was not the shock. The shock actually came in two waves: first when I saw how much food she ate 10 Chicken Tenders, a medium order of French fries, and about six ounces of a Frosty with crushed M&M's and then when I listened to her rave about it.

Now some of the raving may have been her way of thanking me for allowing the unexpected, but after hearing the Chicken Tenders and French fries were "soooo good and the Frosty with crushed M&M's was "to die for," I couldn't help but remember research I had read last year and wonder: was this little girl already addicted to this junk?

According to at least one study, it's quite possible.

In the study, researchers at Scripps Research Institute in Florida gave a group of rats unlimited access to the sorts of junk foods humans eat. Sausage, pound cake, bacon, and cheesecake all high-fat foods like the Chicken Tenders, French fries, and Frosty my niece ate were some of the items used.

Compared to two other groups of rats, one that was fed only healthy foods and one that was fed junk food but in limited amounts, the unlimited-access group ate twice the amount of calories and quickly became obese.

But the real surprise came when the researchers electronically stimulated the rats' brains. After only five days on the unlimited-junk-food diet, the pleasure center in the rats' brains had become desensitized, meaning they'd now require more junk food to receive the same amount of pleasure from it.

Paul Johnson, a coauthor of the study, called this "the hallmark of addiction," a fact that became shockingly evident, when electronic shock was used.

The researchers allowed the rats from all three groups to eat junk food and then shocked their feet. The rats used to eating healthy food and those who ate junk food in restricted amounts quickly stopped eating because of the pain.

But the rats from the unlimited-junk-food group did not even once they realized the shocks would continue if they continued to eat the junk food.

A second study published last year in the Proceedings of the National Academy of Sciences studied the problem from another angle and found that fat-rich foods like Kobi's choices at Wendy's not only send a signal that the body is full but also create pleasant long-term memories of the experience. It's these pleasant memories that make the smells from the doughnut shop or the commercial for the pizza place or Kobi's single previous experience eating a Frosty such a powerful lure.

All this leads to a question you probably have for me: If fast food is so powerful, why in the world did you let your niece decide where and what to eat?

It's a matter of principal.

I believe in the power of the will. I believe that while you can give a child many things love, support, guidance there's is one thing that you cannot give them.

A will.

If Kobi eats the right things just because Uncle KK makes her, what good is that going to do? She eats only once or twice a week with Uncle KK.

Even at the age of eight, she needs to decide the way she'll lead her life. She needs to discover for herself whether it take two more months or 10 more years that healthy eating and regular exercise do nothing more than make you feel good.

I only hope and pray that when that day comes, her will can overcome what just might be an addiction.