If you eat a high glycemic diet with foods like white bread, sugary soda, white potatoes, and white rice, you will experience insulin spikes. This we know. What we don’t know (sorry Josh) is whether this sort of diet will directly affect acne.
Scientists hypothesize that a high glycemic diet and its resulting insulin reaction will result in higher levels of hormones (IGF-1 and androgens) which may contribute to clogged pores and increased skin oil production.
When it comes to high glycemic diets in particular, scientists also postulate that eating this way may lower the amount of beneficial proteins (IGFBP-3) and natural retinoids, which help keep skin cell growth in check and pores from becoming clogged.
However, as is becoming customary in my research on diet and acne, we do not have enough research to make any strong correlations. The only 2 studies which have been done on glycemic load and acne have been performed by the same group of Australian researchers, led by Robin Smith, and while acne lesion counts appear to reduce on low glycemic diets, results are inconclusive. What stands out most sharply is the lingering question of whether glycemic load leads to decreased acne symptoms or whether it is the weight loss that tends to go hand in hand with this sort of diet that causes the reduction in acne. To answer this question, we need data on whether a reduction in acne symptoms is sustained after weight loss has leveled off. Until then, I’m happy that the scientific community is at least starting to investigate.