Should I change my Diet? Does diet/ fatty food affect acne?

Historically the role of diet in acne was thought to be a myth. However recent studies have suggested that diary products and foods with high glycaemic index can influence hormonal and inflammatory factors, which can increase acne prevalence and severity. Studies have been inconclusive regarding the association between acne and other foods.

So in essence, yes if possible avoid foods with high fat content and foods with a high glycemic index (see the wikipedia link above).