Although most experts agree that chocolate and greasy foods do not cause acne, it is also known that what you eat can show up on your skin, and one way this happens is through hormones.

Studies link acne to Western-style diets (high in sugar and calories), eating sugar and refined carbohydrates causes the pancreas to release large amounts of insulin and IGF-1.
Over time this type of diet leads to insulin resistance and chronically high levels of these acne-causing hormones.

Eating minimally processed, low glycaemic index foods can reverse the situation, and this has been now demonstrated in several studies. But it’s not only sugar that gives you pimples; dairy products are also to blame. What’s the role of milk? To help baby cows grow.
Milk has plenty of IGF-1 and other growth hormones.

These hormones make their way into your blood and eventually to your skin where they stimulate sebum production and skin cell growth.
One has to consider all contributing factors when it comes to acne.