The role of food ingestion in the causation of acne is a controversial one. Most dermatology text books swear that there is no role and most dermatologists toe the line.
But personally I would say that food habits definitely do affect the pathophysiology of acne and acneiform eruptions. A friend, who is a dermatologists, have said to me that for acne skin care treatment, one can always first watch ones diet.
Many of her patients who have been on remission without clinical acne after treatment) and on a "no chocolate, no ice cream, no cola, no fried fast food' regimen have come back experiencing severe outbreaks after they restart their junk food habits!
And she says that this has been proven in more than two decades of solid observations! Thus, chocolates and fatty food are best avoided if you are a person with acne prone skin.