This is because glucose is the main source of heat provided by the brain, and starch is the fastest and easiest element to convert into glucose. So if you don't eat starch, the brain's reaction will slow down, leading to inattention and poor memory. In addition, in order to stabilize blood sugar and energy required by human activities, when you eat starchy food occasionally, your body may have many adverse effects of absorption and hoarding. Therefore, it is recommended to eat less and never eat.