advantages of junk foods.....?

I don't think junk food is all that bad for you when used in moderation. I like to treat myself with some unhealthy foods once in a while. I don't think there are many nutricional benefits but I do see benefits of learning self control and discipline. I don't allow my children to have a lot of "chips and cookies". They do get them as treats though on special occassions. They never ask for them in the store and never demand them. I thnk it can be an effective tool in certain situations as well.

since when is pizza junk food?

Well, the human body needs all kinds of nutrition, so "junk" food should also be part of the diet.
Since junk food is usually things that are fatty and sugary, and overall very unhealthy, it might be bad if too much is eaten. But you still have to take some, because you need that fat and sugar, you need some of that... whatever it is in the food.
The human diet needs all this stuff, but only in small amounts, to maintain a health diet.

Hello rajka970. To be honest, junk food has no advantages. Junk food just clog up your arteries, and causes arthritis and heart problems. Grease, sugar, fat, sodium, and other things are very unhealthy. Humans should eat only a tiny portion of it. It is said in the food pyramid that only a bite of a sugar cookie is enough for the day. I don't eat much junk food, only pizza most of the time.Have a great day, funorb12.