Cellulose and its derivatives have been utilized as additives and functional fibers in food industries. The solubility has been traditionally used to categorize cellulose derivatives, whilst their complex effects within food matrix are less understood. In this study, insoluble forms i.e., cellulose and ethyl cellulose (EC), and soluble forms i.e., methylcellulose (MC) and sodium carboxymethylcellulose (Na-CMC) were selected to investigate the mechanisms by which the two groups of cellulose ingredients regulate in vitro digestibility of starch-based foods. In the Michaelis-Menton analysis, the addition of insoluble cellulose or EC as inhibitors tended to decrease the V