Acne happens when hair follicles get blocked by too much of a natural skin oil called sebum. Skin bacteria that doesn’t usually cause any problems can then grow in the blocked pores and cause acne papules, pustules or nodules. Acne is not a sign of poor hygiene. In fact, excessive washing and scrubbing can irritate your skin and make acne worse. There is no scientific evidence that foods such as chips, chocolate or pizza cause breakouts. If your acne is being managed properly, what you eat shouldn't affect your skin.