Malnutrition and loss of appetite. RS3 American resistant starch is an improved starch, which is considered to be helpful to improve intestinal health, control blood sugar and reduce fat intake. However, because RS3 American resistant starch cannot be digested and absorbed, if the human body takes it as the main energy source for a long time, it will lead to malnutrition, poor taste and taste, and a large intake will also lead to loss of appetite.