I heard that 30% of waste is excreted from your skin. so does eating bad with greasy food give you acne?

Let's talk...: The claim that 30% of waste is excreted through your skin is bunk. The one waste product that you lose through your skin is urea and this loss is significant only if you sweat; the stuff is also famously nontoxic. There's actually a consistency rare among scientific studies that diet doesn't affect acne -- i was surprised too. You're an adult and can read critically. Thanks for asking.