Is it true that fattening and sugar affects acne?

Somewhat. What you put in is what you get out. A poor diet will not reflect clear glowing skin. Drink plenty of water and eat lots of fruits and vegetables.
False. Acne is a produc of a inflamatory reaction caused for propioneum bacterium. Common belief is that fatty food such as chocolate and nuts may cause it but is a belief only. This a combination between dirt, skin oils and bacteria altogether with inflamatory mediators in any given time. Affects the sebaceous glands in the face.