Pizza is the same as bread, lots of proteins and fat. Add a salad, and you're doing just fine. Ice cream is milk with sugar. None of which does any bad for running, however for the mental side of things I think ice cream should be a threat or during sommer holiday.
Nothing wrong with pizza except, however most I buy in store aren't any good in taste.
If you're running 100 miles a week, some ice cream will not hurt you. Your nutrients are met with all the other food you're eating. No need to eat 3500 kcal of nutrient-packed food like broccolies. That is neither healthy or practically.