There is still no definite answer to this question. The original studies were done in the 1960s and compared patients to those eating sugar sweets. However, they didn’t compare high-GI foods to lower ones. There is mounting evidence to suggest that a lower GI diet has acne benefits.
This is further supported by the reduced occurrence/lack of acne in teenagers in non-developed countries. A low GI and high protein diet has been shown to be beneficial to acne sufferers as they have fewer incidents of outbursts.