I think many children hear negative expressions about fast food, when in fact, not all fast food is bad. There are many kinds of fast food that are very healthy and can be made in a short time at home or at a commercial outlet. Sometimes, the faster it is to make the food, the fresher and healthier it is.
It is true there are many places where you can get fast junk food containing mostly fillers, sugar and fat, but why not change the whole concept of fast food and teach our kids that what is important is the quality of the food, not the speed of making it.