When does acne start ? Acne is most common in adolescents with up to 90% of teenagers suffering at one time or another. However acne can occur at anytime. If you are in your twenties, thirties, forties and fifties and have acne you are not alone. Does my diet affect acne ? There is no link between acne and diet. It is a myth that chocolate and fried foods cause acne or make it worse. However it is true to say that a good balanced diet will improve your general well being and this will be reflected in your skin condition. Is acne caused by dirt ? No. In fact if anything, people who have oily skin have cleaner skin than average because they wash it more often. However washing the skin too often can make spots worse because it makes the skin dry and sore. Washing your skin twice daily is plenty.