The reason behind this is the high GI levels of these foods (Scientific American). GI levels, short for Glycemic Index Levels, are numbers that demonstrate the effect of a food on the human body's blood sugar levels. The high level on the GI scale is 100, which corresponds to glucose (Harvard Health). High GI levels cause an increase in insulin levels in the body, which causes dryness and flaking of the skin. Dry, flaky skin leads to clogged pores and acne formation. Even though pores are clogged, the body continues to create oils that build up under the skin and cause red eyes.