TLDR: eating greasy foods does NOT cause acne. Certainly, if every time you eat pizza, you get zits, then don’t eat pizza as much if you don’t want zits. But the research shows that what you eat is not related to acne.
Some studies show that people who adhere to a diet with a low glycemic load can help lessen skin issues such as acne.
Stay hydrated! Drinking eight or more glasses of water a day helps rid the body and skin of toxins.
Direct skin contact with greasy or oily substances directly to the skin can cause an acne breakout. e.g. french fries on greasy fingers that touch your face.