Cornstarch is a carbohydrate, and excess consumption carries similar risks as high dietary intake of other carbohydrates. The main consequence of overeating carbohydrates is weight gain and obesity, reports Medical Daily. Cornstarch contains essentially no vitamins, minerals, fiber or protein, notes SFGate.
Some people eat cornstarch due to an eating disorder known as amylophagia, a form of pica, claims Psychology Today. Individuals suffering from amylophagia may consume over two to three boxes of cornstarch a week. This practice causes blood glucose levels to skyrocket and puts sufferers at risk for diabetes. Other symptoms of excessive cornstarch consumption include iron deficiency anemia, intestinal obstruction and malnutrition, reports HealthGuideInfo.com.