My son eats pretty much whatever we eat within the confines of a child's tastes. When he was little, he never ate cookies, candy -- and his only indulgence was ice cream -- if he was in the mood. We rarely went out for fast food even.
As he hit the 1st or 2nd grade, it seemingly caught up to him. Not sure if his tastes changed or just that so many other kids seem to enjoy junk or what the case was. I will tell you though, that when he does eat crappy (or too much junk) he does not feel good at all.
So I give him what we eat -- and sometimes he enjoys it other times, for example having steamed chicken - he will poke at it and ask if I could ever make fried!
When he eats garbage, I am not too tempted. I am not a sweets person so that is not an issue, and I do not have a liking for fast food (except pizza).
So, while at times watching him eat ice cream can be tempting, generally if I swipe a spoonful, it will satisfy me.
Now, if he is eating a plate full fries (not fast food) and a bacon cheeseburger....well that is tougher for me!