Acne in adults is a chronic, increasingly common disease, especially among women. It differs in pathogenesis and clinical presentation from adolescent acne. Acne in adults is associated with Western diet, defined as high consumption of milk, high glycemic load and high calorie intake. Metabolic signals of this diet result in a significant increase in insulin/insulin growth factor 1 serum level and consequently in the molecular interplay of mammalian target of rapamycin complex 1 kinase (mTORC1)/forkhead box protein 1 (FoxO1) mediated nutrient signaling, leading to increased proliferation of keratinocytes, increased lipogenesis and sebum production and finally to aggravation of acne.