One of my all-time favorite topics. For a long time, the party line in dermatology is that diet does not affect acne. And frankly, I always thought that was ridiculous. How can what you put in your body not affect the largest organ of your body. I mean, it just makes no sense.
Finally, the tide is turning and there are a few good studies published in medical journals about diet and acne. There are only 2 things you need to remember:
I have listened to patients for years say they break out when they eat a lot of sugar. And they were right!!!!! A study published in Australia in 2007 of forty-three 15-25 year-old men showed that the men that ate 25% energy from protein and 45% from low-glycemic-index carbohydrates had significant improvements in their acne. They also lost weight and their insulin sensitivity increased. The latter is important because low insulin sensitivity is associated with Type II diabetes. The other group emphasized carbohydrate-dense foods without reference to the glycemic index, and did not experience those positive outcomes. The following link shows glycemic index for some common foods.
http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm
A December 2012 well done 600+ person study from Italy published in a Journal of the American Academy of Dermatology showed:
Cybele Fishman, MD