The frying oil is not changed often
Most of the items at fast-food restaurants are fried, and if you’ve handled a deep fryer before you know, it’s a pain to change all that oil. It takes ages to heat, too, so the easiest thing to do is not change it.
The problem with used oil is that oil burns and releases harmful chemicals, cancer-harmful, so it’s not only all that trans-fat, it’s dangerous compounds as well.
